Kansas State Swine Day 2011 Report of Progress

SWINE DAY 2011

 

Contents

V  Foreword

V  Standard Abbreviations

VI  K-State Vitamin and Trace Mineral Premixes

VII  Biological Variability and Chances of Error

 

Herd Health

1  A PRRS CAP Update on the Regional Control and Elimination of PRRSV

6  Is Aerosol Transmission an Important Risk for PRRSV Transmission? An Example of How Simple Biosecurity Procedures Can Prevent Virus Spread Within a Barn

12  Utilizing Vaccination for Porcine Circovirus Type 2 as a Tool to Aid Elimination of PCV2 from Swine Populations

 

Nursery Nutrition and Management

34  The Effects of Orally Supplemented Vitamin D3 on Serum 25(OH)D3 Concentrations and Growth of Pre-Weaning and Nursery Pigs

46  The Effects of High-Sulfate Water and Zeolite (Clinoptilolite) on Nursery Pig Performance

57  Effects of Feeding Copper and Feed-Grade Antimicrobials on the Growth Performance of Weanling Pigs

62  Effects of Liquitein on Weanling Pigs Administered a Porcine Circovirus Type 2 and Mycoplasma hyopneumoniae Vaccine Strategy S

70  Effect of Total Lysine:Crude Protein Ratio on Growth Performance of Nursery Pigs from 15 to 25 lb

75  Effect of Replacing Commonly Used Specialty Protein Sources with Crystalline Amino Acids on Growth Performance of Nursery Pigs from 15 to 25 lb

81  Evaluation of Heparin Production By-Products in Nursery Pig Diets

90  Evaluating the Effects of Pelleting Deoxynivalenol-Contaminated Dried Distillers Grains with Solubles in the Presence of Sodium Metabisulfite on Analyzed DON Levels

96  Evaluating the Effects of Pelleting, Corn Dried Distillers Grains with Solubles Source, and Supplementing Sodium Metabisulfite in Nursery Pig Diets Contaminated with Deoxynivalenol

105  Evaluating the Effects of Pelleting, Dried Distillers Grains with Solubles Source, and Supplemental Sodium Metabisulfite in Nursery Pig Diets Contaminated with Deoxynivalenol

114  Effects of Increasing Dietary Wheat Middlings on Nursery Pig Growth Performance

118  The Effects of Sorghum Dried Distillers Grains with Solubles on Nursery Pig Performance

129  Effects of XFE Liquid Energy and Choice White Grease on Nursery Pig Performance

138  Influence of Standardized Ileal Digestible Tryptophan:Lysine Ratio on Growth Performance of 13- to 21-lb Nursery Pigs

145  Influence of Dietary Isoleucine:Lysine Ratio on the Optimal Tryptophan:Lysine Ratio for 13- to 24-lb Pigs

 

Finishing Nutrition and Management

155  Determining the Effects of Tryptophan:Lysine Ratios in Diets Containing 30% Dried Distillers Grains with Solubles on Growth Performance of 157- to 285-lb Pigs

162  Determining the Effects of L-Tryptophan Addition to Diets Containing 30% Dried Distillers Grains with Solubles on Finishing Pig Growth Performance

168  Determining the Effects of Tryptophan:Lysine Ratio in Diets Containing Dried Distillers Grains with Solubles on Growth Performance of Finishing Pigs

174  Determining the Effect of the Ratio of Tryptophan to Large Neutral Amino Acids on the Growth Performance of Finishing Pigs

182  The Effects of Sorghum Dried Distillers Grains with Solubles on Finishing Pig Growth Performance, Carcass Characteristics, and Fat Quality

197  Effect of Regrinding Dried Distillers Grains with Solubles on Finishing Pig Growth Performance

202  Effects of Lowering Dietary NDF Levels Prior to Marketing on Finishing Pig Growth Performance, Carcass Characteristics, Carcass Fat Quality, and Intestinal Weights

216  Effects of Increasing NDF from Either Dried Distillers Grains With Solubles or Wheat Middlings, Individually or in Combination, on the Growth Performance, Carcass Characteristics, and Carcass Fat Quality in GrowingFinishing Pigs

227  Effects of Xylanase in Growing-Finishing Diets Varying in Dietary Energy and Fiber on Growth Performance, Carcass Characteristics, and Nutrient Digestibility

240  The Effect of Bacillus Probiotic on Growth Performance and Fecal Consistency of Growing-Finishing Pigs

247  The Effects of Diet Form and Feeder Design on the Growth Performance of Finishing Pigs

257  The Effects of Feeder Design (Conventional Dry vs. Wet-Dry) in the Nursery and in the Finisher on Growth Performance of Finishing Pigs

262  Effects of Stocking Density on Lightweight Pig Performance Prior to Marketing

266  Evaluation of Ractopamine HCl Feeding Programs on Growth Performance and Carcass Characteristics of Finishing Pigs

272  Effects of Diet Mix Time on Growth Performance of Finishing Pigs Fed Ractopamine HCl

278  Effects of Abrupt Changes between Mash and Pellet Diets on Growth Performance in Finishing Pigs

282  Effects of Sorghum Particle Size on Milling Characteristics, Growth Performance, and Carcass Characteristics in Finishing Pigs

288  Effects of Adding Cracked Corn to a Pelleted Supplement for Nursery and Finishing Pigs

301  Effect of Sample Size and Method of Sampling Pig Weights on the Accuracy of Estimating the Mean Weight of the Population

319  Effects of Dietary L-Carnitine and DDGS on Growth, Carcass Characteristics, and Loin and Fat Quality of Growing-Finishing Pigs

330  Effects of Dietary Astaxanthin and Ractopamine HCl on the Growth and Carcass Characteristics of Finishing Pigs and the Color Shelf-Life of Longissimus Chops from Barrows and Gilts

 

Meat Quality

341  Effect of Sorghum Dried Distillers Grains with Solubles on Composition, Retail Stability, and Sensory Attributes of Ground Pork from Barrows and Gilts

354  Index of Key Words

355  Acknowledgments

357  The Livestock and Meat Industry Council, Inc.

 

Foreword

It is with great pleasure that we present the 2011 Swine Industry Day Report of Progress. This report contains updates and summaries of applied and basic research conducted at Kansas State University during the past year. We hope that the information will be of benefit as we attempt to meet the needs of the Kansas swine industry.

 

2011 Swine Day Report of Progress

Editors

Bob Goodband

Mike Tokach

Steve Dritz

Joel DeRouchey

 

Standard Abbreviations

 

ADG = average daily gain

ADF = acid detergent fiber

ADFI = average daily feed intake

AI = artificial insemination avg. = average bu = bushel

BW = body weight cm = centimeter(s)

CP = crude protein

CV = coefficient of variation cwt = 100 lb d = day(s)

DE = digestible energy

DM = dry matter

DMI = dry matter intake

F/G = feed efficiency

ft = foot(feet)

ft2 = square foot(feet)

g = gram(s)

µg = microgram(s), .001 mg

gal = gallon(s)

GE = gross energy

h = hour(s)

HCW = hot carcass weight

in. = inch(es)

IU = international unit(s)

kg = kilogram(s)

kcal = kilocalorie(s)

kWh = kilowatt hour(s)

lb = pound(s)

Mcal = megacalorie(s)

ME = metabolizable energy

mEq = milliequivalent(s)

min = minute(s)

mg = milligram(s)

mL = cc (cubic centimeters)

mm = millimeter(s)

mo = month(s)

N = nitrogen

NE = net energy

NDF = neutral detergent fiber

ng = nanogram(s), .001 Fg

no. = number

NRC = National Research Council

ppb = parts per billion

ppm = parts per million

psi = pounds per sq. in.

sec = second(s)

SE = standard error

SEM = standard error of the mean

SEW = segregated early weaning

wk = week(s)

wt = weight(s) yr = year(s)

 

K-State Vitamin and Trace Mineral Premixes

 

Diets listed in this report contain the following vitamin and trace mineral premixes unless otherwise specified.

• Trace mineral premix: Each pound of premix contains 12 g Mn, 50 g Fe, 50 g Zn, 5 g Cu, 90 mg I, and 90 mg Se.
•  Vitamin premix: Each pound of premix contains 2,000,000 IU vitamin A, 300,000 IU vitamin D3, 8,000 IU vitamin E, 800 mg menadione, 1,500 mg riboflavin, 5,000 mg pantothenic acid, 9,000 mg niacin, and 7 mg vitamin B12.
•  Sow add pack: Each pound of premix contains 100,000 mg choline, 40 mg biotin, 300 mg folic acid, and 900 mg pyridoxine.

 

Note

Some of the research reported here was carried out under special FDA clearances that apply only to investigational uses at approved research institutions. Materials that require FDA clearances may be used in the field only at the levels and for the use specified in that clearance.

 

Biological Variability and Chances of Error

 

Variability among individual animals in an experiment leads to problems in interpreting the results. Animals on treatment X may have higher average daily gains than those on treatment Y, but variability within treatments may indicate that the differences in production between X and Y were not the result of the treatment alone. Statistical analysis allows us to calculate the probability that such differences are from treatment rather than from chance.

 

In some of the articles herein, you will see the notation “P < 0.05.” That means the probability of the differences resulting from chance is less than 5%. If two averages are said to be “significantly different,” the probability is less than 5% that the difference is from chance or the probability exceeds 95% that the difference resulted from the treatments applied.

 

Some papers report correlations or measures of the relationship between traits. The relationship may be positive (both traits tend to get larger or smaller together) or negative (as one trait gets larger, the other gets smaller). A perfect correlation is one (+1 or -1). If there is no relationship, the correlation is zero.

 

In other papers, you may see an average given as 2.5 ± 0.1. The 2.5 is the average; 0.1 is the “standard error.” The standard error is calculated to be 68% certain that the real average (with unlimited number of animals) would fall within one standard error from the average, in this case between 2.4 and 2.6.

 

Many animals per treatment, replicating treatments several times, and using uniform animals increase the probability of finding real differences when they exist. Statistical analysis allows more valid interpretation of the results, regardless of the number of animals. In all the research reported herein, statistical analyses are included to increase the confidence you can place in the results.

 

A PRRS CAP Update on the Regional Control and Elimination of PRRSV1

 

R. R. R. Rowland2

 

Summary

The control and elimination of porcine reproductive and respiratory syndrome virus (PRRSV) represents one of the most challenging tasks facing the swine industry worldwide. Several factors related to the biology of the virus make disease detection and elimination difficult. Efforts are further hampered by a lack of vaccines that can protect naïve herds from infection. With this in mind, elimination efforts that incorporate existing tools and knowledge are being initiated. The principal focus is at the region level. One example of success is the Stevens County project in Minnesota, which has attained a PRRSV-negative status and has been expanded to include all of northern Minnesota.

Key words: PRRSV, PRRSV control and elimination

 

Introduction

Porcine reproductive and respiratory syndrome (PRRS), initially described in the late 1980s as “Mystery Swine Disease,” is associated with reproductive failure in sows, respiratory distress in nursery pigs, and poor growth performance during finishing. Severe outbreaks result in abortion storms accompanied by high sow mortality. The causative agent of PRRS, PRRS virus (PRRSV), was first isolated and identified by investigators in the Netherlands and later in the United States. Viruses of European origin were first identified in U.S herds in 1999, and have further complicated efforts to control the virus.

 

The entry of PRRSV into a production system can occur through the introduction of infected pigs or the use of PRRSV-contaminated semen. Other avenues for introduction include mechanical vectors. A fourth route is through so-called area spread, which includes aerosols. Transmission by aerosols is still poorly understood; however, a recent report indicates that under the right conditions, PRRSV can travel up to 6 miles (Otake et al., 2010)3 .

 

After entering a production system, PRRSV is efficiently transmitted both horizontally (pig-to-pig infection) and vertically (transplacental infection). Pigs may become subclinical carriers, further perpetuating the virus. The continued maintenance of the virus as a subclinical continuous infection is termed endemicity, which is periodically punctuated by outbreaks that result in high mortality and economic loss.

 

PRRSV has the capacity to generate a large degree of genetic diversity in both structural and non-structural proteins, which has proved an obstacle for vaccine development (Lunney et al., 2010⁴ ). An alternative to vaccination is controlled exposure or acclimation, which involves the intentional infection of naïve animals with wild-type live PRRSV, either through contact with infected animals or exposure to infectious material. Controlled exposure is an attempt to induce immunity against farm-specific strains; however, the intentional exposure of young animals to virulent virus presents unintended consequences, such as the risk of introducing other pathogens.

 

Although PRRSV appears to be a formidable pathogen, the virus is relatively unstable under normal environmental conditions and is especially sensitive to UV radiation (Cutler et al., 2011⁵ ). The virus has been documented to travel up to 6 miles, but aerial transmission of the virus over long distances appears to be a rare event and dependent on a set of ideal environmental conditions. For example, we found that 10 PRRSVnegative sentinel pigs separated by a distance of less than 30 ft from 190 experimentally infected pigs failed to become infected during continuous exposure over 42 d (see “Is Aerosol Transmission an Important Risk for PRRSV Transmission? An Example of How Simple Biosecurity Procedures can Prevent Virus Spread within a Barn,” p. 6).

 

Virus stability is also affected by temperature. Jacobs et al. (2010⁶ ) calculated T^1/2 values of 1.6, 27.4, 84.8 and 155.5 h for temperatures of 86, 68, 50 and 40oF, respectively. The virus is completely inactivated after a short incubation at temperatures greater than 130oF (Bloemrad et al., 1994⁷ ); therefore, the application of common antimicrobial agents or steam is sufficient to completely inactivate PRRSV on surfaces.

 

The Control of PRRSV at the Herd Level

Since the discovery of the disease, several approaches have been employed for the control and elimination of PRRSV in single herds (Corzo et al., 2010⁸ ). Highly effective approaches include depopulation-repopulation and all-in, all-out methods. Both depend on the placement of PRRSV-negative pigs in a facility that is “free” of virus. Herd closure and rollover is the most common method for eliminating virus from sow farms. The technique is based on observations that new PRRSV infections gradually decrease in closed herds. The typical length for herd closure is approximately 220 d, which approximates the maximum period that PRRSV can persist in a pig. All remaining seropositive animals are removed and replaced with negative pigs. The most recent tool for preventing the entry of PRRSV into a virus-negative herd is whole-barn filtration combined with negative pressure ventilation. Filtration is designed to block the aerosol entry of PRRSV and other pathogens (Dee et al. 2010⁹ ). Despite its expense, filtration has proved to be a promising method reducing risk of PRRSV transmission into herds in pig-dense regions.

 

The Control and Elimination of PRRSV at the Regional Level

Eliminating PRRSV from a single herd by exploiting the virus’ biological properties has become relatively easy, but a renewed outbreak is all but inevitable. One strategy for reducing the risk of reintroduction to a single farm is to expand disease and virus control efforts to the region level. This approach is based on the idea that the elimination of PRRSV in a region containing multiple farms will reduce the risk of PRRSV introduction into any single farm. The regional elimination concept has evolved into several regional elimination projects that are supported by private companies and the USDA-funded PRRS Coordinated Agricultural Project (PRRS CAP).

 

The steps for the initiation and operation of a regional elimination project are summarized below. Detailed descriptions of useful tools and specific biosecurity protocols can be downloaded at the PRRS CAP website (www.prrs.org).

 

1. Define the boundaries that constitute a region suitable for conducting PRRSV elimination and determine the level of participation.

A region is defined by a set of boundaries consisting of natural and/or man-made barriers, such as lakes, cities, mountains, or areas where a cluster of farms is spatially separated from other pig producing sites. The most practical approach is to define a region as a county, but this designation can suffer from serious limitations primarily because viruses do not respect county lines.

 

The scope and ultimate success of a project is dependent on the level of participation by producers, veterinarians, suppliers, and others, so ongoing communication and producer engagement are critical elements for success. Another important consideration is leadership and the availability of experienced veterinary support.

 

2. Record premises characteristics and herd density.

Location and population size of each site and the overall farm density within a region are mapped and recorded. PRRSV elimination in a region that is dominated by a single type of premises combined with a relatively low density of sites is an ideal situation.

 

3. Determine PRRSV status at each site.

A combination of PRRSV RT-PCR and serology, common diagnostic tests, is used to assess the infection status of individual herds. The amount and frequency of testing needed are determined based on the farm type and level of confidence needed to obtain an accurate result. Holtkamp et al. (2011)¹⁰ describe herd status designations ranging from PRRSV Positive Unstable (Category 1) to PRRSV Negative (Category 4). This common set of terminology is useful for communicating information within a region and for developing standardized reporting methods.

 

¹The work is supported by PRRS CAP, USDA NIFA Award 2008-55620-19132.

² PRRS CAP Project Director, Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506.

³ Otake, S., S. Dee, C. Corzo, S. Oliveira, and J. Deen. 2010. Long-distance airborne transport of infectious PRRSV and Mycoplasma hyopneumoniae from a swine population infected with multiple viral variants. Vet. Microbiol. 145, 198-208.

⁴ Lunney, J., D. Benfield, and R. Rowland. 2010. Porcine reproductive and respiratory syndrome virus: an update on an emerging and re-emerging viral disease of swine. Virus Res. 154, 1-6.

⁵ Cutler, T., C. Wang, Q. Qin, F. Zhou, K. Warren, K. Yoon, S. Hoff, J. Ridpath, and J. Zimmerman. 2011. Kinetics of UV(254) inactivation of selected viral pathogens in a static system. J. Appl. Microbiol. 111, 389-395.

⁶ Jacobs, A., J. Hermann, C. Muñoz-Zanzi, J. Prickett, M. Roof, K. Yoon, and J. Zimmerman, 2010. Stability of porcine reproductive and respiratory syndrome virus at ambient temperatures. J. Vet. Diagn. Invest. 22, 257-260.

⁷ Bloemraad, M., E. de Kluijver, A. Petersen, G. Burkhardt, and G. Wensvoort. 1994. Porcine reproductive and respiratory syndrome: temperature and pH stability of Lelystad virus and its survival in tissue specimens from viraemic pigs. Vet. Microbiol. 42, 361-371.

⁸ Corzo, C., E. Mondaca, S. Wayne, M. Torremorell, S. Dee, P. Davies, and R. Morrison. 2010. Control and elimination of porcine reproductive and respiratory syndrome virus. Virus Res. 154, 185-192.

⁹ Dee, S., S. Otake, and J. Deen. 2010. Use of a production region model to assess the efficacy of various air filtration systems for preventing airborne transmission of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae: results from a 2-year study. Virus Res. 154, 177-184.

¹⁰ Holtkamp, D., D. Polson, M. Torremorell, R. Morrison, D. Augsburger, L. Becton, S. Henry, M. Rodibaugh, R. Rowland, H. Snelson, B. Straw, P. Yeske, and J. Zimmerman. 2011. Terminology for classifying swine herds by porcine reproductive and respiratory syndrome virus status. JSHAP. 19, 44-56.

 

4. Assess overall herd biosecurity and risk for introduction of PRRSV.

The web-based tool, Production Animal Disease Risk Assessment Program (PADRAP), is useful for assessing overall PRRS biosecurity at the herd level and can be a guide for estimating the success of a PRRSV elimination program (www.padrap.org). When reapplied at later time points, the PADRAP can be used to measure improvements in biosecurity over time.

 

5. Map movement of pigs between farms within the region and entering from sources outside the region.

As discussed above, a major biosecurity risk for the entry of PRRSV is through the introduction of PRRSV-infected pigs. A good prospect for PRRSV elimination is a situation where the principal source of pigs and pig transport are confined to sites within the region (intra-regional movement).

 

6. Implement herd control strategies and report progress.

From a menu of herd-based PRRSV elimination methods, summarized above (Corzo et al., 2010), a combination of herd control strategies can be initiated that best fit the type and density of pig farms within the region. Regular status reports are important for updating participants and veterinarians on the progress of the region. Open lines of communication, obtainable goals, and clear criteria related to progress are critical to keeping producers engaged in the process. Reported data include the number of pigs and the PRRSV status for each herd, as well as a general description of progress, including the identification of obstacles to success. Publicized progress provides an incentive for PRRSV-positive farms to make progress toward a negative status.

 

7. Surveillance.

After Category 4 (PRRSV-negative) status is achieved, continued monitoring is important to ensure that farms remain PRRSV-negative. The most common method is to monitor for the presence of PRRSV by standard diagnostic serology. The frequency of sampling is variable, but should be conducted at least twice a year. In addition, herds are monitored for the appearance of PRRS-associated clinical signs.

 

Current Progress

At this time, the PRRS CAP supports seven regional elimination projects, which enroll approximately 2.5 million pigs. The overall elimination effort within the PRRS CAP is directed by Dr. Robert Morrison, University of Minnesota. A list of ongoing PRRSV regional projects conducted in 6 states is below. Each project is designed to address a specific opportunity or challenge related to PRRSV control and elimination. Detailed information on each project, including progress, can be found at www.prrs.org.

 

1.  Illinois – DeKalb Area, Bethany Swine Health Services, Dr. Noel Garbes
2.  Illinois – Western – Tri-County, Carthage Veterinary Service, Ltd., Dr. Dyneah M. Classen
3.  Iowa – Iowa County, Iowa State University, Dr. Derald Holtkamp
4.  Michigan – Allegan & Ottawa Area, Michigan Pork Producers, Dr. James A. Kober
5.  Minnesota – Northern Minnesota Project (above Hwy 212), including Stevens Co., University of Minnesota, Dr. Montse Torremorell
6.  Nebraska – Cuming County, Nebraska Veterinary Service, Dr. Alan Snodgrass
7.  Pennsylvania – Pennsylvania Project, University of Pennsylvania, Dr. Thomas D. Parsons

 

An example of success is found in the Stevens County project, which was recently expanded into the Northern Minnesota Project (Corzo, 2010). Stevens County is 1,490 km² and contains 87 pig sites (164,000 pigs), including sow farms, boar studs, nurseries, and growing-finishing operations. Only 4 farms declined to participate in the project. As a region, Stevens County is relatively isolated from other pig-associated sites. At the beginning of the project in 2004, 29 sites were PRRSV-positive, 19 sites negative, and the remaining sites of unknown status. As of 2010, all sites were negative for PRRSV, with only sporadic outbreaks in sow farms. In all cases, the outbreaks were linked to the import of PRRSV-positive pigs from outside the region. Recently, the project was expanded to include all of Minnesota north of Hwy 212, a region that includes approximately 1 million pigs.

 

Recent Advances in Support of PRRSV Elimination

New technologies and methodologies are being employed to improve the effectiveness and lower the costs of PRRSV elimination. For example, oral fluid samples can be used as a substitute for the detection of PRRSV infection (Kittawornrat et al., 2010)11. Oral fluid is collected by allowing pigs in a single pen to chew on a rope. Fluid is extracted by squeezing the contents of the rope into a collection container. The oral fluid sample is processed and can be assayed in a manner similar to a routine diagnostic serum sample with only a few modifications. Advantages in the use of oral fluids include the ease of collection, a decrease in pig stress, and the ability to efficiently survey an entire population. Another advancement in support of regional elimination is in the area of riskbased testing and surveillance. Current sampling methods include the application of a standard one-size-fits-all protocol. In a risk-based approach, the historical biosecurity status of a farm and surrounding farms, combined with other information, is incorporated to create a herd-specific sampling regimen that maximize surveillance while minimizing cost.

 

The application of genomic and genetic approaches to identifying genes associated with PRRS resistance, susceptibility, or tolerance has far-reaching implications in the control and elimination of PRRSV. One goal of a genetic approach is to perform markerassisted selection to develop pig breeds with improved PRRS-resistance, and to avoid the unintended selection of traits that increase disease susceptibility. Current efforts and progress related to understanding the genetics of disease resistance can be found at www.PRRS.org.

 

Conclusion

The success of a regional elimination project can be measured on two levels. The first is the installation of a process that fosters communication, education, and improved biosecurity awareness among producers who seek a common goal. The second level is the demonstration that PRRSV has been eliminated, a process that can be expected to require a much longer-term commitment.

 

¹¹ Kittawornrat, A., J. Prickett, W. Chittick, C. Wang, M. Engle, J. Johnson, D. Patnayak, T. Schwartz, D. Whitney, C. Olson, K. Schwartz, and J. Zimmerman. 2010. Porcine reproductive and respiratory syndrome virus (PRRSV) in serum and oral fluid samples from individual boars: will oral fluid replace serum for PRRSV surveillance? Virus Res. 154, 170-176.

 

Is Aerosol Transmission an Important Risk for PRRSV Transmission? An Example of How Simple Biosecurity Procedures Can Prevent Virus Spread Within a Barn¹

 

B. R. Trible and R. R. R. Rowland²

 

Summary

Understanding the transmission of porcine reproductive and respiratory syndrome virus (PRRSV) is important for developing methods to control and eliminate the virus. In this study, 2 similar experiments were performed involving 10 sentinel pigs maintained for 42 d in close proximity to 190 pigs experimentally infected with a highly pathogenic PRRSV isolate. All pigs were monitored for PRRSV infection by PCR and serology. In the first experiment, virus transmission to sentinel pigs was detected within 21 d after infection of the source population of pigs. In the second experiment, a small separation distance of 27 ft combined with simple biosecurity procedures was sufficient to prevent the transmission of virus to sentinel pigs. Overall, the results indicate a low risk associated with PRRSV spread by aerosols and reinforce the importance of maintaining good biosecurity procedures.

 

Key words: PRRSV, aerosols

 

Introduction

Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for significant losses to the swine industry. PRRSV infection affects all stages of production, causing reproductive failure in pregnant gilts or sows, respiratory disease and high mortality in nursery pigs, and decreased performance during finishing. Established routes of virus spread include movement of infected pigs and the use of virus-contaminated semen. A third route is through the introduction of virus by mechanical vectors, such as contaminated equipment. A fourth route is termed area spread, which includes other non-human associated transmission such as contaminated aerosols and other unknown mechanisms. Experimental models of virus spread via aerosols have reported maximum transmission distances ranging from 1.5 ft to 5.5 miles (Dee et al., 2010; Otake et al., 2010)^3,4; however, the results of experiments documenting distance of 3 and 5.5 miles did not incorporate direct pig-to-pig transmission as the means of detecting infection (Dee et al., 2006; Otake et al., 2010)⁵ .

 

 

As part of a large study involving the infection of hundreds of pigs with a highly pathogenic PRRSV isolate, we sought to determine if implementing a few biosecurity procedures would prevent the aerial spread of PRRSV in a facility that possessed some of the features found in commercial production settings.

 

Procedures

Animal experiments were initiated after review and approval by the Kansas State University Institutional Animal Care and Use Committee. For each experiment, ~200 high-health pigs were randomly distributed at a density of 10 to 15 pigs per pen (12 ft by 12 ft). A diagram of the facility is shown in Figure 1A. Each pen consisted of a solid concrete floor separated by either solid concrete partitions or metal-framed partitions covered by hard plastic. A metal-framed gate was located at the front of each pen to allow access for personnel while keeping the pens relatively open. Pens were washed daily by animal caretakers and effluent material was allowed to flow out the front of each pen into a central floor drain (Figure 1A).

 

The virus challenge consisted of 105 50% tissue culture infectious doses of the PRRSV isolate NVSL 97-7895. This isolate was selected based on its relatively high pathogenic properties (Willis et al., 1997⁶ ). Half of the 3 mL virus inoculum was administered intranasally and the remainder was given intramuscularly. Pigs were monitored daily for clinical signs and received appropriate veterinary care as needed. Experiments were terminated 42 d after infection.

 

Blood samples were collected from all pigs on d 0, 4, 7, 11, 14, 21, 28, 35, and 42 postinfection. Animal care and scientific personnel donned protective equipment, including disposable Tyvek coveralls, nitrile gloves, and foot covers. A footbath filled with disinfectant (Trifectant; Alpha Tech Pet, Littleton, MA) was placed in the walkway for workers to clean boots before entering or leaving animal areas. PRRSV diagnostic assays, including PCR and ELISA, were performed by personnel at the Kansas State Veterinary Diagnostic Laboratory

 

Can. J. Vet. Res. 70:168-175.

 

 

Results

Experiment 1. For the first experiment, biosecurity procedures included a one-way flow of personnel from the clean area to the infected area (Figure 1B). Personnel entered through a single door, donned protective gear, then worked with the sentinel pigs prior to entering the infected pig area. The experimentally challenged pigs exhibited clinical signs, including lethargy and respiratory distress, which first appeared within 1 wk after challenge. Infection was confirmed by PRRSV qRT-PCR, with the first positive results appearing on d 4 postinfection and positive serology beginning on d 14 (Figure 2A, Table 1). The sentinel pigs became PRRSV-positive on d 21 (6 out of 10 pigs were PCR-positive) followed by seroconversion on d 35. By the end of the study, all sentinel pigs were PCR- and antibody-positive for PRRSV. The results from Experiment 1 demonstrated that PRRSV NVSL 97-7895 was transmitted between infected and sentinel pigs. Transmission likely occurred during peak levels of viremia in the viruschallenged pigs. The transmission of virus to sentinel pigs was not the result of direct pig-to-pig contact, but could have occurred through the aerosol spread of virus, either by virus released into the air by infected pigs or by droplets generated during the washing of pens. Other possibilities included the movement of personnel or contaminated materials from the infected area, back through the gate, and into the clean area.

 

Experiment 2. Experiment 2 was performed in the same manner as Experiment 1, with the exception of three changes in biosecurity (Figure 1C). The first was an increase in separation from 17 ft to 27 ft between sentinel pigs and the nearest infected pen. The second change was the replacement of the gate with a barrier fence to prevent the movement of personnel between clean and infected areas. Finally, the clean and infected areas had separate personnel entrances and exits. The infection and immune response of the challenge pigs followed the same course as Experiment 1 (see Figure 2B and Table 1). In this experiment, the sentinel pigs remained PRRSV PCR-negative and seronegative throughout the 42-d exposure to the infected pigs (Figure 2B, Table 1).

 

Discussion

The model used in this study incorporates several features relevant for understanding mechanisms of aerosol transmission, including (1) a large source population infected with a highly pathogenic PRRSV isolate, (2) the placement of sentinel pigs and infected pigs within the same facility that shared the same air space, and (3) the exposure of sentinel pigs for an extended period of time. The results from this study indicate that the risk of the spread of PRRSV via aerosols is likely minimal and supports the observations and conclusions of several previous studies showing that aerosol spread of PRRSV is limited to a couple of meters. This is in contrast to recent reports indicating that isolates such as MN-184 can spread via aerosols over distances of several miles. The PRRSV isolate used in this study shares characteristics similar to MN-184 in terms of pathogenicity and the capacity to replicate to high titers within pigs (Johnson et al., 2004; Osorio, et al., 2002; Troung et al., 2004).^7,8,9 MN-184 was reported to travel up to 9.1 km from the source of the virus, which was 300 experimentally infected pigs (Otake et al., 2010), whereas in this study, 190 pigs infected with NVSL 97-7895 were unable to infect pigs at a distance of approximately 27 ft. The reason for this discrepancy is unclear. One possibility is related to the method used to determine virus spread. In this study, pig-to-pig transmission was used as the indicator of aerosol spread. In contrast, the spread of MN-184 was measured by assaying the contents of concentrated air samples collected at various distances from the source population. Although infectious virus particles were identified by virus isolation and swine bioassays, whether these methods accurately replicate the conditions of pig-to-pig aerosol transmission found in the field is unknown.

¹The work is supported by PRRS CAP, USDA NIFA Award 2008-55620-19132.

² PRRS CAP Project Director, Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506.

³ Dee S., S. Otake, and J. Deen. 2010. Use of a production region model to assess the efficacy of various air filtration systems for preventing airborne transmission of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae: results from a 2-year study. Virus Res. 154:177-184.

⁴ Otake S., S. Dee, C. Corzo, S. Oliveira, and J. Deen. 2010. Long-distance airborne transport of infectious PRRSV and Mycoplasma hyopneumoniae from a swine population infected with multiple viral variants. Vet. Microbiol. 145:198-208.

⁵ Dee S., J. Deen, J. Cano, L. Batista, and C. Pijoan. 2006. Further evaluation of alternative air-filtration systems for reducing the transmission of Porcine reproductive and respiratory syndrome virus by aerosol.

⁶ Willis R., J. Zimmerman, S. Swenson, K. Yoon, H. Hill, D. Bundy, and M. McGinley. 1997. Transmission of PRRSV by direct, close, or indirect contact. Swine Health Prod. 213-218.

⁷ Johnson W., M. Roof, E. Vaughn, J. Christopher-Hennings, C. R. Johnson, and M. Murtaugh. 2004. Pathogenic and humoral immune responses to porcine reproductive and respiratory syndrome virus (PRRSV) are related to viral load in acute infection. Vet. Immunol. Immunopathol. 102:233-247.

⁸ Osorio F., J. Galeota, E. Nelson, B. Brodersen, A. Doster, R. Wills, F. Zuckermann, and W. Laegreid. 2002. Passive transfer of virus-specific antibodies confers protection against reproductive failure induced by a virulent strain of porcine reproductive and respiratory syndrome virus and establishes sterilizing immunity. Virology 302:9-20.

⁹ Truong H., Z. Lu, G. Kutish, J. Galeota, F. Osorio, and A. K. Pattnaik. 2004. A highly pathogenic porcine reproductive and respiratory syndrome virus generated from an infectious cDNA clone retains the in vivo virulence and transmissibility properties of the parental virus. Virology 325:308-319.

 

Although the transmission of PRRSV in aerosols was not seen in this study, we cannot conclude that area spread never occurs; however, our results indicate that simple changes in biosecurity procedures, including the redirection of personnel flow and a relatively small distance between infected and non-infected pigs, reduced PRRSV transmission risk within an experimental facility.

 

Figure 1. Layout of the PRRSV challenge facility used to house the experimentally infected and sentinel pigs.

A shows the general layout of the facility including dimensions and location of the central floor drain. The flow of personnel; the location of gates, barriers, entrances and exits; and the areas designated as clean and infected are shown in B (Experiment 1) and C (Experiment 2). For B and C, the gray and white areas denote infected and clean areas, respectively. Pigs were located in numbered pens. The sentinel pigs were placed in pen 1.

 

Figure 2. PRRSV load in reference and infected pig sera.

Quantitative RT-PCR was performed as described in Procedures. The average of the log10 of PRRSV templates per reaction for infected and sentinel pigs is shown for Experiment 1 (A) and Experiment 2 (B). Filled circles and non-filled circles show the means for infected pigs and sentinel pigs in each panel, respectively. Standard deviations are represented by horizontal and vertical lines within each panel.

 

Table 1. Serum antibody levels against PRRSV as detected by ELISA

 

¹ Includes all pigs in the sentinel group.

² Includes the mean sample to positive ratio (S/P) for all pigs in the infected group (approximately 200 pigs).

³ Values indicate S/P of the PRRS ELISA. Shaded numbers indicate a positive result (S/P > 0.39).

 

Utilizing Vaccination for Porcine Circovirus Type 2 as a Tool to Aid Elimination of PCV2 from Swine Populations^1,2

 

M. L. Potter³ , S. S. Dritz⁴ , R. A. Hesse⁴ , R. R. R. Rowland⁴ , J. C. Nietfeld⁴ , R. Oberst⁴ , S. C. Henry³ , L. M. Tokach³ , M. Hays⁴ , A. Fuller⁴ , B. E. Straw⁵ , and R. O. Bates⁶

 

Summary

A total of 928 pigs from the Swine Teaching and Research Centers at Michigan State University (MSU) and Kansas State University (KSU) and a Kansas commercial farm were used during a 3-year study to determine whether circovirus vaccination influenced porcine circovirus type 2 (PCV2) circulation within a herd and could be used as a tool to eliminate PCV2 from PCV2-positive swine herds. Infection with PCV2 was confirmed in both university herds before circovirus vaccine introduction. After vaccination implementation, vaccinated barrows from consecutive groups were serially tested for viremia. Follow-up antibody and growth testing with vaccinated and nonvaccinated pigs was performed at the KSU farm. In a circovirus-vaccinated commercial herd, testing of non-circovirus-vaccinated pigs for viremia was completed. Environmental swab samples were collected from facilities at the KSU and commercial farms for PCV2 DNA detection.

 

Sera from 0 of 9 MSU vaccinated-cohorts and 3 of 10 KSU vaccinated-cohorts had detectable PCV2 DNA. From follow-up testing, a PCV2 antibody rise after vaccination was detected for vaccinated pigs with no detectable antibody rise for non-vaccinated pigs. Overall growth rate of non-vaccinated pigs tended (P = 0.07) to increase compared with vaccinated pigs. Non-vaccinated pigs became PCV2 viremic at the commercial farm. Viral DNA was detected in the environment of the commercial farm but not in the KSU facilities.

 

Therefore, circovirus vaccine can affect viral circulation on farms but would need to be used in conjunction with other management practices to eliminate PCV2 from most swine populations.

 

Key words: circovirus, disease elimination, PCV2, swine, vaccine

 

Introduction

Infection with porcine circovirus type 2 (PCV2) can result in a multi-syndrome disease, porcine circovirus disease (PCVD).⁷ Identified in diagnostic laboratory samples in the early 1990s, PCV2 has affected most U.S. swine herds. Despite a long history of PCV2 circulation within the swine population, vaccines against PCV2 have been commercially available only since 2006.⁸ Initial studies evaluating the effects of circovirus vaccination on production parameters in PCV2-affected herds indicate that vaccination was effective at reducing finishing phase mortality and increasing pig growth rate.^9,10,11 In single-cohort studies, vaccination with commercial or experimental vaccines against PCV2 reduced viremia^10,11 and decreased viral shedding in nasal secretions and feces,^12,13 but data evaluating the effects of vaccination on PCV2 viral circulation within a herd over time are limited. Our goal was to monitor PCV2 viral circulation in swine herds after implementing a circovirus vaccination program for growing pigs. The short-term objective of this project was to determine whether circovirus vaccination could be used to affect viral circulation within 2 farrow-to-finish herds. The long-term objective of the project was to understand whether use of circovirus vaccines over time in PCV2- positive swine herds could provide a tool to eliminate PCV2 from these herds.

 

Procedures

Procedures used in these studies were approved by the Kansas State University and Michigan State University Institutional Animal Care and Use Committees.

 

Herd History. The MSU and KSU Swine Teaching and Research Centers were singlelocation farrow-to-finish operations. Pigs were moved through the KSU farm in an all-in, all-out manner in nursery, grower, or finisher rooms. In the MSU farm, about half of the pigs placed in a nursery, grower, or finisher room were moved in and out at a time. Pigs were born (farrowed) at each farm approximately every 4 (MSU) or 5 (KSU) wk, which resulted in growing pig populations of about 300 pigs in each age group. Both herds were negative for porcine reproductive and respiratory syndrome virus, and the MSU herd was negative for Mycoplasma hyopneumoniae (M. hyo). Pigs at the KSU farm were vaccinated at weaning for M. hyo (RespiSure-ONE; Pfizer Animal Health, New York, NY), which, along with other management procedures, contributed to low levels of clinical disease. Prior to the start of our study, both farms had been closed to live animal introductions, but semen was introduced from outside sources. In October 2007, the KSU farm began to bring replacement gilts from an outside source into the herd approximately every 9 wk.

 

Clinical history. The KSU farm did not have any clinical signs of PCVD noted before the baseline testing and subsequent implementation of a circovirus vaccination program, although prior to baseline testing, histopathologic evaluation on tissues of one pig documented lymphoid depletion lesions consistent with PCVD. The MSU farm had evidence of moderate clinical PCVD (10 to 15% nursery mortality) prior to baseline testing.

 

Phase 1: Baseline testing procedures. In early 2007, a cross-sectional survey was conducted of both university herds to verify the presence of PCV2 and to characterize patterns of PCV2 infection and seroconversion. At the MSU farm, blood was collected from 101 pigs across a total of 5 growing pig populations (6 to 10, 11 to 15, 16 to 20, 21 to 25, and 26 to 30 wk of age). Within the KSU farm, 141 pigs were sampled across 5 growing pig populations (4, 9, 14, 19, and 24 wk of age). Serum was pooled (MSU: 21 pools, and KSU: 27 pools) within age group and analyzed using the Kansas State Veterinary Diagnostic Laboratory (KSVDL) PCV2 PCR assay for detection of PCV2 nucleic acid. Viral template quantities for each serum pool were log10 transformed and transformed results were averaged for pools within each age range to characterize the changes in viral load. For the detection of PCV2 antibodies, individual serum samples were tested using the 96-well format KSVDL PCV2 indirect fluorescent antibody (IFA) assay with serial 1:2 dilutions beginning with a 1:20 serum to phosphate-buffered saline dilution and ending with a 1:2,560 ratio. The titration endpoint was calculated as the reciprocal of the last serum dilution that gave a positive result.

 

All IFA titers were log2 transformed to approximate a normal distribution prior to descriptive analysis. For samples that did not have antibody detected at the most concentrated dilution (1:20), the log₂ of 10 was used in the analysis. For samples that were strongly positive at the least concentrated dilution (1:2,560), the log₂ of 5,120 was used. This approach allowed results to be weighted differently than samples with antibody detected with a normal level of fluorescence at the 1:20 and 1:2,560 dilutions.

 

Infection and antibody profiles obtained from the baseline testing were considered when deciding on sampling times for the Phase 2 study on each farm.

 

Phase 2: Trial procedures. In the spring of 2007, both MSU and KSU initiated circovirus vaccination programs. A 2-dose circovirus vaccine (Circumvent PCV; Intervet/ Schering-Plough, Millsboro, DE) was administered as an intramuscular injection (2 mL per dose) to all growing pigs in each weaning group with 3 to 5 wk between vaccine doses. Pigs were weaned and vaccinated with the first dose of circovirus vaccine at approximately 3 wk of age at the KSU farm, but weaning age and timing of first vaccination at the MSU farm varied (range: 2 to 6 wk).

 

From 2007 through 2008, barrows from consecutive weaning cohorts at the MSU (9 groups) and KSU (10 groups) farms were monitored for PCV2 viremia. A minimum of 12 barrows per group from different litters were randomly selected, ear-tagged, and serially bled at 4 time points: weaning or just before vaccination, entry-to-finishing, mid-finishing, and end-of-finishing. After completion of data collection in 2008, individual serum samples for pigs with complete serum sets (4 serum samples per pig) were tested by the KSVDL PCV2 PCR assay for detection of PCV2 nucleic acid. An average of 40 cycles was run with a cycle time threshold of 0.05 for classification of PCV2 nucleic acid-containing (positive) samples.

 

Phase 3: Follow-up monitoring procedures. Beginning in the spring of 2009, a total of 372 pigs (186 non-vaccinated control pigs and 186 circovirus-vaccinated pigs) across 3 weaning groups were used in a Phase 3 growth and PCV2 antibody follow-up study at the KSU farm. At the start of the Phase 3 study, the KSU farm had been vaccinating pigs against PCV2 for the previous 2 years. During that time there had been no evidence of clinical disease. A first objective of this follow-up study was to document the effects of circovirus vaccination on PCV2 antibody titers and to determine whether there was evidence of PCV2 exposure. A second objective of this Phase 3 study was to evaluate the effects of circovirus vaccination on growth rate of pigs in the KSU herd.

 

Three groups of pigs were used in the Phase 3 study. Groups 1 and 2 had 7 pigs per nursery pen. A total of 18 barrow pairs (36 pigs; 1 pair in each of 18 pens) for group 1 and 30 barrow pairs (60 pigs; 1 pair in each of 30 pens) for group 2 were utilized. Within a pen, a pair of barrows was selected with one barrow per pair randomly allotted to a vaccinated treatment and the pen-mate barrow assigned to the non-vaccinated control treatment. Barrows assigned to the vaccinated treatment were injected intramuscularly with a 2-dose circovirus vaccine (Circumvent PCV) at approximately 3 and 6 wk of age. All other pigs in the weaning group not enrolled in the follow-up study were vaccinated with the same 2-dose circovirus vaccine.

 

Throughout the entire study, pairs of barrows remained penned together. Barrows were individually weighed and bled at 4 time points: d 0 (pre-vaccination), entry-tofinisher, mid-finishing, and end-of-finishing. From these data, ADG was calculated for 3 periods: nursery and grower, finisher, and overall nursery to finisher. Removals and mortalities were recorded and weighed and their gain and time on test were included in performance calculations.

 

For group 3, 138 barrow or gilt pairs (276 pigs) were randomly allotted to treatments (vaccinated or non-vaccinated control) at the time of weaning with procedures similar to those used for groups 1 and 2. For group 3, 6 or 8 pigs were assigned to each nursery pen (3 or 4 pairs within a pen) and all pigs were placed on test. Pigs assigned to the vaccinated treatment were injected intramuscularly with a 2-dose circovirus vaccine (Circumvent PCV) at approximately 3 and 9 wk of age. Weighing and penning procedures for each pair were similar to those used for groups 1 and 2. A subset of 20 barrow pairs (40 pigs) from 20 different pens distributed throughout the nursery were bled at the time of weighing. Pairs of barrows were selected and, within each pair, one barrow was randomly assigned to a vaccinated treatment and the pen-mate barrow assigned to the non-vaccinated control treatment. For group 3, removals and mortalities were recorded and weighed and their gain and time on test were included in performance calculations.

 

Individual serum samples for groups 1, 2, and 3 were tested for PCV2 antibodies using the KSVDL IFA assay. Test procedures used were similar to those used in Phase 1; however, an initial serum to phosphate-buffered saline dilution of 1:40 was used with subsequent serial 1:3 dilutions for group 1, 2, and 3 samples. Testing was performed over 7 d (2 d for group 1, 3 d for group 2, and 2 d for group 3), and pairs of pigs were balanced across IFA days within each study.

 

Group 1, 2, and 3 IFA titers were log₃ transformed to approximate a normal distribution prior to statistical analysis. For samples that did not have antibody detected at the most concentrated dilution (1:40), the log₃ of 13.3 was used in the analysis, whereas the log3 of 262,440 was used for analysis for samples that were strongly positive at the least concentrated dilution (1:87,480). This approach allowed these samples to be weighted differently than positive samples with normal level fluorescence at 1:40 and 1:87,480.

 

Group 1, 2, and 3 IFA data were analyzed by repeated measures analysis using the GLIMMIX procedure in SAS version 9.1.3 (SAS Institute, Inc., Cary, NC). Fixed effects in the model included treatment, time, and their interaction. Group and IFA day were used as random effects. Differences between treatments were determined using least squares means (P < 0.05). Log₃ transformed least squares means were transformed back to the original scale for presentation as geometric mean titers (GMT).

 

Growth data were analyzed using the GLIMMIX procedure in SAS version 9.1.3. The interaction with gender and treatment was determined to be non-significant for group 3, and growth data were pooled across the genders for subsequent analysis of the treatment effect. Thus, growth data for all 3 groups were analyzed using a single model. Treatment was a fixed effect and group was included as a random effect. Differences between treatments were determined using least squares means (P < 0.05).

 

Phase 4: Monitoring for PCV2 under commercial conditions. A commercial farm in Kansas that was determined to have had severe PCVD before circovirus vaccine became available was selected as a herd for an additional monitoring study (Phase 4) because of proximity and clinical history. Prior to the introduction of circovirus vaccine, postweaning mortality had ranged from 5% to 19%. After implementation of a circovirus vaccination program (Circumvent PCV), the herd had less apparent clinical disease (mortality: 4 to 9%). The circovirus vaccination program had been in place for a year before our Phase 4 study began. In addition to the history of PCV2 infection, porcine reproductive and respiratory syndrome virus and M. hyo also contributed to the health challenges in the nursery and finishing phases of production. Pigs were weaned from a sow farm in western Kansas and moved to eastern Kansas to be placed at a nurseryfinishing site with 2 nursery barns with 4 rooms each and 8 finishing barns. Pigs were moved all-in, all-out by nursery room and finishing barn.

 

A total of 85 pigs (1.7 to 3.1 wk of age) from a 1,100-pig weaning group were ear-tagged and bled just prior to weaning. These 85 pigs were not vaccinated against PCV2 and were monitored for 9 wk. All other pigs in the weaning group were vaccinated according to standard farm protocol with a 2-dose circovirus vaccine (Circumvent PCV). The 85 non-vaccinated sentinel pigs were initially penned in 4 pens in the nursery room that also contained pens of circovirus-vaccinated pigs. If pigs were removed from their initial pens because of illness or injury, they were moved to a sick pig pen but were still monitored. After approximately 8 wk in the nursery, pigs were moved to a single finisher barn at the same farm location and were placed in pens according to their vaccination status. Pigs were bled approximately every 3 wk for a total of 4 sampling times (sampling time age ranges: 1.7 to 3.1, 4.9 to 6.3, 7.9 to 9.3, and 10.9 to 12.3 wk of age). The objective of this monitoring effort was to determine whether non-vaccinated pigs housed in barns with pigs vaccinated against PCV2 became viremic with PCV2 after circovirus vaccine was used in the herd for a year.

 

Serum samples were pooled (5 samples per pool) within age range and were analyzed by the KSVDL PCV2 PCR assay for presence of PCV2 nucleic acid. Genotype of PCV2 (PCV2a or PCV2b) was determined for samples with detectable PCV2 nucleic acid.

 

Phase 5: Monitoring for PCV2 in the environment of swine barns. As pigs involved in all previous phases of this study were exposed to different environments and pigs over time, we wanted to determine whether documentable sources of PCV2 exposure existed. The objective for this phase of monitoring was to demonstrate applicability of swabbing and PCV2 PCR testing as a method for monitoring PCV2 levels on environmental surfaces in swine production facilities.

 

Swab samples were collected from the nursery and finisher rooms at both the KSU farm and the commercial farm in eastern Kansas that was used in the Phase 4 study. Cotton swabs were used to sample the floor slats, gating, waterers, feeders, fans and heaters in the nursery or finishing rooms. Swabs were placed in vials containing enriched media. For each farm, samples were pooled within nursery or finishing production phases (2 KSU nursery or finishing pools and 16 commercial farm nursery or finishing pools). A uniform amount of this pooled suspension was tested by KSVDL PCV2 PCR for detection of PCV2 nucleic acid.

 

Results

Phase 1. Baseline PCV2 IFA testing of the serum collected from pigs from the MSU herd demonstrated that passively acquired antibody declined by 15 wk of age (Figure 1). Higher levels of antibody were apparent in pigs 16 to 20 wk of age or older. PCV2 nucleic acid was detected by PCR in serum samples from pigs 11 to 15 wk of age and older (Figure 2).

 

In the baseline analysis of the KSU herd (Phase 1), passively acquired antibody in growing pigs declined by 19 wk of age with higher levels of antibody detected following this decline (Figure 3). Viremia was detectable only in populations consisting of pigs that were 19 and 24 wk of age (Figure 4). The 19-wk-old pigs were viremic but did not have antibody levels suggestive of seroconversion.

 

Phase 2. After introduction of circovirus vaccination, PCV2 PCR testing of serum samples collected over time from 9 MSU and 10 KSU cohort groups showed a different infection pattern on each farm compared with baseline PCR profiles. From the MSU farm, PCV2 PCR testing on sera collected from 86 barrows at 4 sampling points (prevaccination, entry-to-finishing, mid-finishing, and end-of-finishing) failed to detect PCV2 nucleic DNA (Table 1).

 

From the KSU farm, testing by PCV2 PCR on serum samples from 111 barrows failed to detect nucleic acid (PCV2 PCR negative) in samples collected at any time from pigs in groups 1, 2, 4, 7, 8, 9, and 10 (Table 2). Serum samples with detectable PCV2 DNA (PCV2 PCR positive) were found in group 3 (10%, 1/10 samples from mid-finishing), group 5 (25%, 3/12 samples from weaning; 25%, 3/12 samples from entry-to-finishing; 8.3%, 1/12 samples from mid-finishing; and 8.3%, 1/12 samples from end-of-finishing), and group 6 (8.3%, 1/12 samples from entry-to-finishing). For serum samples with detectable DNA, viral template quantity ranged from 5 to 379 viral template copies per reaction. In only 1 (group 5) of the 10 groups (10%) did a pig remain viremic for longer than 1 testing interval. Overall, no PCV2 viral DNA was detected in samples from 7 of the 10 groups (70%) monitored over a time period of greater than 1 year.

 

Phase 3. After 2 years of vaccinating growing pigs against PCV2 at the KSU farm, subsamples of pigs were allocated to a circovirus-vaccinated treatment or a non-vaccinated control treatment in a growth and PCV2 antibody follow-up study (Phase 3). An interaction (P < 0.001) between treatment and time occurred for antibody level (Table 3). With the exception of the initial bleed (d 0; during the wk of weaning) when control and vaccinated pig antibody levels were similar (P = 0.41), vaccinated pigs had increased (P < 0.001) PCV2 antibody levels compared with controls at all other sampling times. The magnitude of the antibody responses varied over time for control and vaccinated pigs, as did the pattern of antibody production or decay. By the time the pigs were placed into the finisher, control pig antibody levels had declined (P < 0.001) compared with their respective d 0 levels; however, control pig antibody levels remained similar (P ≥ 0.61) throughout the finishing period. In contrast, compared with their respective d 0 antibody levels, vaccinated pigs had an increase (P < 0.001) in PCV2 antibody titer by the time of entering the finisher, which decreased (P < 0.001) by each of the subsequent sampling points.

 

During the nursery and grower periods, vaccinated pigs had decreased (P = 0.005; Table 4) ADG compared with non-vaccinated control pigs. Vaccinated and control pigs had similar (P = 0.30) finishing ADG, although growth rates for vaccinated pigs continued to be numerically less than control pig growth rates. Overall, a tendency (P = 0.07) was observed for vaccinated pigs to have decreased ADG compared with control pigs. These growth rate differences resulted in control pigs entering the finisher 2.6 lb heavier (P = 0.03) than vaccinated pigs. When pigs were taken off test at the end of the finishing period, control pigs had a numeric weight advantage (P = 0.16) of 4.4 lb over vaccinated pigs.

 

Phase 4. Results obtained from the commercial farm with a 1-year history of circovirus vaccination differed from those observed in the KSU farm. From a serial sampling of 85 non-vaccinated sentinel pigs, no PCV2 DNA was detected in the weaning pools (0/17 pools; Table 5). In contrast, PCV2 nucleic acid was detected in pooled samples at each of 3 subsequent sampling ages (4.9 to 6.3 wk of age: 1/17 pools; 7.9 to 9.3 wk of age: 6/16 pools; and 10.9 to 12.3 wk of age: 12/16 pools). Genotype was reported for each pool. PCV2a was detected in all but 1 pool (4.9 to 6.3 wk of age: 1/17 pools; 7.9 to 9.3 wk of age: 6/16 pools; and 10.9 to 12.3 wk of age: 11/16 pools), but PCV2b was not detected in any of the pools until 10.9 to 12.3 wk of age (2/16 pools).

 

Phase 5. Environmental swabbing and testing by PCV2 PCR (Figure 5) detected PCV2 DNA in samples from 8 commercial nursery and 8 commercial finisher barns. In contrast, the presence of PCV2 DNA was not detected by PCV2 PCR testing of environmental swab samples from the KSU farm.

 

Discussion

This was a first study to evaluate the effects of circovirus vaccination on viral circulation at the herd level. Our study was designed to begin to evaluate the hypothesis that circovirus vaccination programs in herds would affect viremia and subsequent viral shedding into the environment. Over time, a reduction in environmental contamination coupled with continued use of circovirus vaccine to build immunity in growing pigs prior to viral exposure would aid derivation of PCV2-free herds.

 

The MSU and KSU herds and management served as models for commercial multisite swine production systems. Based on the Phase 1 baseline testing, PCV2 was detected in both swine populations, although viremia was not increased until after the nursery period. This testing provided evidence for primarily horizontal rather than vertical transmission. Both herds had PCV2-viremic pigs during finishing and showed evidence that pigs likely seroconverted after the documented time for onset of viremia (Figures 1, 2, 3, and 4).

 

Although both farms had evident viral circulation during finishing, the MSU pigs experienced an earlier onset of viremia than the KSU pigs. Both herds were considered good models in which to monitor the effects of circovirus vaccination long-term because baseline results from both non-vaccinated populations indicated viral presence and seroconversion-supporting antibody profiles.

 

Circovirus vaccination programs were started in each herd in the spring of 2007, and monitoring of barrows from each farrowing group began. In the MSU herd, viremia was not detected in serum collected at any sampling point from circovirus-vaccinated barrows (Table 1). During the same time, there were no reports of clinical PCVD from the farm, but some pigs may have become transiently viremic between sampling points; however, the MSU farm baseline testing indicated onset of viremia early in the finishing phase and infection appeared to be detectable in a portion of the population throughout finishing. Thus, the MSU vaccinated pig PCR data demonstrate that vaccination had an effect on the viral circulation within this farm by either shortening the duration of viremia or preventing it altogether.

 

In the KSU herd, 3 groups had at least 1 pig with detectable PCV2 DNA in the serum. These groups (3, 5, and 6; Table 2) were not consecutive groups, nor were the ages at the time of detectable viremia consistent among groups. In addition, only 1 group had pigs testing positive for PCV2 at more than 1 sampling point. Although the viral load evels between sampling points were not known, the PCV2 viral loads detected in the positive serum samples among the 4 bleeding times were 379 template copies per reaction or less. Additionally, none of the viremic vaccinated pigs or their group-mates had been identified as PCVD suspects. Evidence of PCV2 problems was restricted to PCR detection of transient viremia. Although PCV2 was intermittently detected among vaccinated pigs, because no naïve pigs were in the population, the virus was not able to transmit readily, propagate within groups, and establish widespread infection within the herd; therefore, the KSU herd results indicate immunization by circovirus vaccination affected viral circulation by controlling the spread of virus and shortening the duration of viremia or by preventing the infection entirely .

 

The follow-up study (Phase 3) was performed at the KSU farm to verify that circovirus vaccination had affected within-farm viral circulation patterns and to determine the farm’s new PCV2 status. Results indicate a change in the herd PCV2 antibody profile. Pigs for this follow-up study were born primarily from dams that were vaccinated against circovirus as weaned pigs; however, gilts or sows were not vaccinated against circovirus prior to breeding or during gestation. Before vaccine introduction into the herd, pigs had antibody decay until mid-finishing followed by high levels of antibody in late-finishing, so the pattern after 2 years of continuous vaccination was different. Antibody levels at the time of weaning were similar and low for pigs assigned to the control or vaccinated treatments (Table 3). After vaccination, vaccinated pigs had a rise in antibody by the beginning of the finishing period that then decreased throughout finishing. In contrast, control pigs had decay in antibody levels through the beginning of finishing and never had a rise in antibody levels. The lack of antibody rise suggests that control pigs were not exposed to the PCV2 virus during the time period for sampling. Residual PCV2 virus shed from previously infected pigs and present in the environment did not appear to stimulate an immune response in these control pigs, nor did it appear that there was exposure to PCV2 virus transmitted from vaccinated but infected pigs within the groups. These follow-up KSU results indicate that the virus had either been eliminated from the herd and farm facilities, or had fallen below the threshold that could trigger stimulation of the immune system.

 

Growth rate has been used as an indicator of disease and was therefore included as a response for this study. In our study, circovirus vaccination negatively affected growth rate during the nursery and grower periods (Table 4). This resulted in vaccinated pigs 2.6 lb lighter than non-vaccinated control pigs at the beginning of the finishing period.

 

During the finisher phase and for the overall study, vaccinated pigs had numerically reduced ADG compared with control pigs. At the time pigs were taken off test, control pigs had a 4.4 lb numeric weight advantage compared with vaccinated pigs, but the lack of positive growth rate response due to vaccination may be explainable by low or no natural PCV2 challenge in the KSU herd.

 

In our study, vaccinated pigs during finishing did not demonstrate greater ADG compared with non-vaccinated control pigs. Vaccinated pigs were not able to compensate for or overcome the negative effects of vaccination in the nursery. Thus, the immunity built in the nursery and grower period did not provide any benefit during finishing because PCV2 was not present as a challenge to the immune system of the pigs. Therefore, the lack of serologic evidence for PCV2 exposure coupled with the tendency for vaccinated pigs to have poorer overall growth performance than control pigs suggests that PCV2 was not a pathogenic threat for growing pigs in the KSU herd during the follow-up testing.

 

The results that indicated PCV2 was no longer an apparent natural challenge for pigs in the KSU farm could not be replicated in a commercial farm in Kansas despite both farms having implemented long-term circovirus vaccination programs. At the time the data were collected, the commercial farm had been continuously vaccinating pigs for 1 year—slightly less time than the KSU farm. Clinical disease had decreased during the time the vaccine was being used in the commercial herd. The commercial farm moved pigs all-in, all-out from their nursery and finisher rooms and used a disinfectant similar to that of the KSU farm; however, the period of downtime between batches of pigs for cleaning and disinfection of rooms was longer at the KSU farm compared with the commercial farm.

 

In the commercial farm, the non-vaccinated pigs did become viremic after movement into the nursery (Table 5) and exhibited clinical signs of PCVD. The clinical disease in these pigs was apparent even though they constituted a relatively low percentage of the population, and herd immunity did not appear to prevent propagation of the infection; therefore, the belief that housing environment contributed a significant source of PCV2 virus in this population led us to perform the environmental evaluation. We acknowledge that pig-to-pig transmission from viremic pigs could also play a role in the dynamics of the infection, but we believe this was less likely. At each time point, more serum pools had detectable DNA, which indicated that more pigs were becoming infected. In addition, PCV2a was detected first, followed by PCV2b, so the infection profile also changed over time. Whether this differential pattern has biologic significance is yet to be determined.

 

To understand why non-vaccinated pig results differed between the KSU herd and the commercial farm, it was important to identify sources of viral exposure. Pigs at both farms were seemingly weaned free of PCV2, implicating PCV2 in the environment as a primary source of exposure. Swabs were collected in all nursery and finishing rooms at the commercial farm. Nursery and finishing rooms at the KSU farm that had housed study pigs at some point through the 3-year study were also sampled. Although PCR detection of PCV2 nucleic acid does not provide any information about whether the viral material is infectious, it does allow measurement of environmental viral loads that could potentially contain infectious material.

 

In the commercial facility, PCV2 DNA was found in every room and barn. In contrast, at the KSU farm, PCV2 nucleic acid was not detected in either the nursery or finishing facility. Although the infectivity status of the PCV2 DNA detected at the commercial site was not known, any residual infectious material present in the environment could explain why non-vaccinated pigs placed in this facility became viremic shortly after movement into the facility. Complete inactivation of PCV2 was difficult by disinfection under laboratory conditions.¹⁴ Therefore, in our study, with viral material detected in the environment, some infectious virus likely remained. Further investigation of this environmental virus-based route of transmission is warranted to determine the importance of this potential risk.

 

In conclusion, results from this 3-year investigation indicate that circovirus vaccination did affect viral circulation in swine herds. Success in lowering levels or eliminating the virus as a pathogenic threat was achieved at a university research herd, but other exposure risk factors, such as residual PCV2 in the environment, appeared under commercial conditions and inhibited viral elimination efforts. Therefore, circovirus vaccine provides a tool to affect viral circulation on farms but needs to be used in conjunction with other management practices to eliminate PCV2 from most swine populations.

 

¹Appreciation is expressed to the Kansas State University Swine Nutrition Team: Drs. Steve Dritz, Mike Tokach, Jim Nelssen, Bob Goodband, and Joel DeRouchey; the Kansas State and Michigan State swine nutrition and diagnostic medicine/pathology graduate students and undergraduate student employees; Dr. Kyle Horlen, member of the Rowland Laboratory in the Kansas State Veterinary Diagnostic Laboratory; and the Kansas State Swine Research and Teaching Herd Farm Crew, Mark Nelson, Frank Jennings, and Lyle Figge, for their assistance with a variety of supportive procedures including planning and on-farm data collection, manuscript review, and their continued enthusiasm and willingness to make pigs available for sampling purposes.

² Appreciation is expressed to the American Association of Swine Veterinarians, Kansas State University, contributors to the Swine Diagnostic Fund, Michigan State University, and Dr. Brad Thacker (Intervet/ Schering-Plough, Millsboro, DE) for partial funding of this project.

³ Abilene Animal Hospital, PA, Abilene, KS.

⁴ Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

⁵ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University.

⁶ Department of Animal Science, Michigan State University.

⁷ Segalés, J., G. M. Allan, and M. Domingo. 2005. Porcine circovirus diseases. Anim. Health Res. Rev. 6:119-142.

⁸ Opriessnig, T., A. R. Patterson, D. M. Madson, N. Pal, and P. G. Halbur. 2009. Comparison of efficacy of commercial one dose and two dose PCV2 vaccines using a mixed PRRSV-PCV2-SIV clinical infection model 2-3-months post vaccination. Vaccine 27:1002-1007.

⁹ K. P. Horlen, S. S. Dritz, J. C. Nietfeld, S. C. Henry, R. A. Hesse, R. Oberst, M. Hays, J. Anderson, and R. R. Rowland. 2008. A field evaluation of mortality rate and growth performance in pigs vaccinated against porcine circovirus type 2. J Am. Vet. Med. Assoc. 232:906-912.

¹⁰ Fachinger, V., R. Bischoff, S. B. Jedidia, A. Saalmüller, and K. Elbers. 2008. The effect of vaccination against porcine circovirus type 2 in pigs suffering from porcine respiratory disease complex. Vaccine 26:1488-1499.

¹¹ Kixmöller, M., M. Ritzmann, M. Eddicks, A. Saalmüller, K. Elbers, and V. Fachinger. 2008. Reduction of PMWS-associated clinical signs and co-infections by vaccination against PCV2. Vaccine 26:3443- 3451.

¹² Fort, M., M. Sibila, A. Allepuz, E. Mateu, R. Roerink, and J. Segalés. 2008. Porcine circovirus type 2 (PCV2) vaccination of conventional pigs prevents viremia against PCV2 isolates of different genotypes and geographic origins. Vaccine 26:1063-1071.

¹³ Fort, M., M. Sibila, E. Pérez-Martín, M. Nofrarías, E. Mateu, and J. Segalés. 2009. One dose of a porcine circovirus 2 (PCV2) sub-unit vaccine administered to 3-week-old conventional piglets elicits cellmediated immunity and significantly reduces PCV2 viremia in an experimental model. Vaccine 27:4031- 4037.

¹⁴ Royer, R. L., P. Nawagitgul, P. G. Halbur, and P. S. Paul. 2001. Susceptibility of porcine circovirus type 2 to commercial and laboratory disinfectants. J. Swine Health Prod. 9:281-284.

 

Table 1. Detection of porcine circovirus type 2 (PCV2) nucleic acid in serum samples serially collected from barrows across 9 consecutive weaning groups enrolled in a postcircovirus-vaccination implementation monitoring program at the Michigan State University Swine Teaching and Research Center¹

 

******TABLE 1 GOES HERE*******

 

Table 2. Detection of porcine circovirus type 2 (PCV2) nucleic acid in serum samples serially collected from barrows across 10 consecutive weaning groups enrolled in a postcircovirus-vaccination implementation monitoring program at the Kansas State University Swine Teaching and Research Center¹

 

******TABKE 2 GOES HERE******

 

¹A total of 86 barrows (4 samples per barrow) were serially bled and serum was analyzed by PCR for detectable PCV2 DNA. All pigs were vaccinated intramuscularly with 2 doses (2 mL per dose) of Circumvent PCV (Intervet/Schering-Plough Animal Health, Millsboro, DE) after the d 0 blood sample was collected (during the week of weaning).

² Sampling points were during weaning week (d 0; single pre-vaccination serum sample), after entry to the finisher, during mid-finishing, and at the end of the finishing period.

³ An average of 12 barrows were randomly selected across 9 consecutive farrowing groups, ear-tagged, and monitored for their lifetime. Only serum samples from barrows with complete serum sets (4 serum samples per pig) were tested by PCR for detectable PCV2 nucleic acid. Number of pigs reported in the table represents the number of pigs with complete serum sets.

⁴ Interval indicates the amount of time in weeks that had elapsed since the previous sampling point. The d 0 sample was collected during weaning week.

⁵ All serum samples were individually tested by PCR for presence of PCV2 nucleic acid. Results are reported as “yes” if a sample had detectable PCV2 nucleic acid for the indicated group and sampling point, and “no” if no samples had detectable PCV2 nucleic acid.

 

Table 3. Effect of circovirus vaccination and time on indirect fluorescent antibody (IFA) geometric mean titer (GMT) in pigs produced at a farm that had been vaccinating growing pigs against porcine circovirus type 2 (PCV2) continuously for 2 years¹

 

******TABLE 3 GOES HERE******

 

^a,b,c,d,e Means without a common superscript letter differ (P < 0.05).

¹ A total of 136 barrows (68 control and 68 vaccinated pigs) across 3 farrowing groups were ear-tagged and monitored from weaning through finishing at the Kansas State University Swine Teaching and Research Center. Pigs were serially bled on d 0 (within a wk of weaning), after entering the finisher (time elapsed since d 0 range: 8.4 to 8.9 wk), mid-finishing (time elapsed since d 0 range: 13.4 to 13.9 wk), and at the end of the finishing period (time elapsed since d 0 range: 18.0 to 19.4 wk). Antibody levels against PCV2 were determined by IFA testing on individual serum samples. Individual pig IFA titer data were log3 transformed and were analyzed by repeated measures analysis using the GLIMMIX procedure in SAS version 9.1.3 (SAS Institute, Inc., Cary, NC). Fixed effects in the model included treatment, time, and their interaction. Group and IFA day were included as random effects.

² Treatments were non-vaccinated control or vaccinated. Vaccinated pigs were injected intramuscularly with 2 doses (2 mL per dose) of Circumvent PCV (Intervet/Schering-Plough Animal Health, Millsboro, DE) after the d 0 blood sample was collected (during the week of weaning).

³ Geometric mean titers were calculated by taking the mean of the log3 transformed IFA titer values then converting the resulting transformed mean back to the original scale for presentation.

 

Table 4. Effect of circovirus vaccination on growth rate of pigs produced at a farm that had been vaccinating growing pigs against porcine circovirus type 2 (PCV2) continuously for 2 years¹

 

******TABLE 4 GOES HERE******

 

¹ A total of 372 weanling pigs (186 control and 186 vaccinated pigs) across 3 farrowing groups were ear-tagged and monitored from weaning through finishing at the Kansas State University Swine Teaching and Research Center. Pigs were individually weighed on d 0 (within the weaning week and the day of vaccination), after entering the finisher, and at the end of the finishing period to calculate ADG. Growth and on-test time data from mortalities and removed pigs were included in growth and period length calculations. Individual pig growth data were analyzed using the GLIMMIX procedure in SAS version 9.1.3 (SAS Institute, Inc., Cary, NC). The interaction with gender and treatment was determined to be non-significant for group 3, and growth data were pooled across the genders for subsequent analysis. Growth data for all 3 groups were analyzed using a model that included treatment as a fixed effect and group as a random effect.

² Treatments were non-vaccinated control or vaccinated. Vaccinated pigs were injected intramuscularly with 2 doses (2 mL per dose) of Circumvent PCV (Intervet/Schering-Plough Animal Health, Millsboro, DE).

³ Nursery-grower ADG and period length include data from mortalities and removed pigs. The nursery period length did not differ (P = 0.15) between control (59.7 ± 1.48 d) and vaccinated (59.1 ± 1.48 d) pigs.

⁴ Finisher ADG and length include data from mortalities and removed pigs. The number of days for the finisher period did not differ (P = 0.94) between control (71.7 ± 1.13 d) and vaccinated (71.6 ± 1.14 d) pigs.

⁵ Overall ADG and length include data from mortalities and removed pigs. The number of days for the overall trial did not differ (P = 0.96) between control (132.1 ± 2.67 d) and vaccinated (132.1 ± 2.67 d) pigs.

 

Table 5. Detection of porcine circovirus type 2 (PCV2) nucleic acid in serum samples serially collected from pigs not vaccinated for PCV2 in a monitoring program at a commercial farm¹

 

******TABLE 5 GOES HERE******

 

¹ A total of 85 pigs were serially bled and serum was analyzed by PCR for detectable PCV2 DNA. Pigs were not vaccinated for PCV2 at any time during this monitoring period on this commercial farm.

² Pigs were bled initially during the wk of weaning when pig ages ranged from 1.7 to 3.1 wk of age. Pigs were serially bled every 3 wk (on average) thereafter until pigs were 10.9 to 12.3 wk of age.

³ Interval indicates the amount of time in weeks that had elapsed since the initial sampling point. The initial sample was collected during weaning week.

⁴ A total of 5 serum samples were included in a single pool for testing by PCV2 PCR.

⁵ All serum samples were individually tested by PCR for presence of PCV2 nucleic acid. Results are reported as “yes” if a sample had detectable PCV2 nucleic acid for the indicated group and sampling point, and “no” if no samples had detectable PCV2 nucleic acid.

⁶ For serum pools with PCV2 DNA detected, cycle time (Ct) values ranged from 27.7 to 40.7.

 

******FIGURE 1 GOES HERE******

 

Figure 1. Characterization of the porcine circovirus type 2 (PCV2) antibody profile of the Michigan State University (MSU) Swine Teaching and Research Center herd prior to implementation of a circovirus vaccination program.

At the MSU farm, a total of 101 pigs were sampled across 5 growing pig populations (6 to 10, 11 to 15, 16 to 20, 21 to 25, and 26 to 30 wk of age) using a cross-sectional design. Serum samples from individual pigs were tested by the Kansas State University Veterinary Diagnostic Laboratory PCV2 indirect fluorescent antibody (IFA) assay for detection of PCV2 antibodies. All IFA titers were log2 transformed to approximate a normal distribution prior to descriptive analysis. Resulting transformed means were transformed back to the original scale for presentation as geometric mean titers (GMT).

 

******FIGURE 2 GOES HERE******

 

Figure 2. Characterization of the porcine circovirus type 2 (PCV2) infection profile of the Michigan State University (MSU) Swine Teaching and Research Center herd prior to implementation of a circovirus vaccination program.

Serum was pooled (MSU: 21 pools) within age group and analyzed using the Kansas State University Veterinary Diagnostic Laboratory PCV2 PCR assay for detection of PCV2 nucleic acid. Pooled results were log₁₀ transformed and transformed results were averaged within age ranges to characterize patterns for viral load.

 

******FIGURE 3 GOES HERE******

 

Figure 3. Characterization of the porcine circovirus type 2 (PCV2) antibody profile of the Kansas State University (KSU) Swine Teaching and Research Center herd prior to implementation of a circovirus vaccination program.

At the KSU farm, a total of 141 pigs were sampled across 5 growing pig populations (4, 9, 14, 19, and 24 wk of age) using a cross-sectional design. Serum samples from individual pigs were tested by the Kansas State University Veterinary Diagnostic Laboratory PCV2 indirect fluorescent antibody (IFA) assay for detection of PCV2 antibodies. All IFA titers were log2 transformed to approximate a normal distribution prior to descriptive analysis. Resulting transformed means were transformed back to the original scale for presentation as geometric mean titers (GMT).

 

******FIGURE 4 GOES HERE******

 

Figure 4. Characterization of the porcine circovirus type 2 (PCV2) infection profile of the Kansas State University (KSU) Swine Teaching and Research Center herd prior to implementation of a circovirus vaccination program. Serum was pooled (KSU: 27 pools) within age group and analyzed using the Kansas State University Diagnostic Laboratory PCV2 PCR assay for detection of PCV2 nucleic acid. Pooled results were log₁₀ transformed and transformed results were averaged within age ranges to characterize patterns for viral load.

 

******FIGURE 5 GOES HERE******

 

Figure 5. Detection of porcine circovirus type 2 (PCV2) nucleic acid in the environment of nursery and finisher facilities at the Kansas State University (KSU) Swine Teaching and Research Center and a commercial farm. Effect of farm and nursery location on environmental PCV2 DNA detection (A) and effect of farm and finisher location on environmental PCV2 DNA detection (B) are shown below.

Porcine circovirus type 2 (PCV2) PCR results for environmental swabs of Farm A (KSU farm) and Farm B (commercial farm) nursery and finisher locations. Cycle time (Ct) values are reported as 0.0 (no PCV2 DNA detected) or greater than 0.0 (PCV2 DNA detected) with the lower positive Ct values indicative of more PCV2 viral DNA.

 

The Effects of Orally Supplemented Vitamin D3 on Serum 25(OH)D₃ Concentrations and Growth of Pre-Weaning and Nursery Pigs

 

J. R. Flohr, M. D. Tokach, S.S. Dritz¹ , S. C. Henry² , M. L. Potter² , L.M. Tokach² , J. P. Goff³ , R. L. Horst⁴ , J. C. Nietfeld¹ , D. M. Madson⁵ , S. M. Ensley⁵ , R. D. Goodband, J. L. Nelssen, J. R. Bergstrom, and J. M. DeRouchey

 

Summary

A total of 270 pigs from 29 litters (PIC 327 × 1050, initially 2 d of age) were used in a 52-d study to determine the effects of oral vitamin D₃ supplementation on growth performance, serum 25(OH)D₃ concentrations, and bone mineralization of pre- and postweaning pigs. Vitamin D plays an essential role in maintaining proper Ca and P homeostasis within the body of mammals. Because most swine production occurs in environmentally controlled facilities, direct sunlight is no longer a source of vitamin D for the neonatal pig, which could impact bone growth and muscle function.

 

Experimental treatments consisted of 3 oral dosage treatments: (1) control (1 mL peanut oil), (2) 40,000 IU vitamin D₃ delivered in 1 mL peanut oil, or (3) 80,000 IU vitamin D3 delivered in 1 mL peanut oil. Pigs were initially weighed over 2 different days (d 0 or 2), allowing pigs to be placed on test 1 or 2 d after birth. Within a litter, pigs were assigned to similar-weight matched sets of 3 and were allotted to 1 of the 3 oral dosage treatments. Blood samples were collected from pigs of 29 matched sets (87 pigs total) prior to dosing, then the same matched set pigs were bled periodically throughout the trial to measure 25(OH)D₃ serum concentrations. All pigs were weighed again on d 10 and 20. On d 20, pigs were weaned and allotted to the nursery portion of the trial and all pigs were fed common diets from d 20 to 52 of age. Pigs were also randomly selected for necropsy on d 19 and d 35. Eighteen pigs were necropsied on d 19 (6 matched sets for a total of 6 pigs per treatment) and 12 pigs were necropsied on d 35 (6 control pigs and 6 pigs previously dosed with 80,000 IU vitamin D₃). Bone and tissue samples were collected. All bone samples were analyzed for ash content and histopathology.

 

Increasing oral vitamin D₃ increased serum 25(OH)D₃ concentrations on d 10 and 20 (quadratic, P < 0.01), and on d 30 (linear, P < 0.01). During lactation, no differences were observed in ADG across treatments, but at weaning, pigs previously dosed with vitamin D₃ were 0.3 lb heavier than control pigs. Throughout the nursery study (d 20 to 52), no significant differences were observed in ADG, ADFI, or F/G; however, on d 52, pigs previously dosed with vitamin D₃ were 0.5 lb heavier than control pigs. Vitamin D3 supplementation had no effect on bone ash concentration of either the femur or 2nd rib. Pathologic lesions were not identified by microscopic evaluation of bone, regardless of vitamin D₃ treatment. Oral vitamin D₃ did not influence growth performance or bone measurements in this study, but more research may be needed to test the response under field conditions with more health challenges.

 

Key words: nursery pig, vitamin D, 25(OH)D₃

 

Introduction

Vitamin D is a group of fat-soluble secosteriods. The two major physiologically relevant forms of vitamin D are vitamin D₂ (ergocalciferol) and vitamin D₃ (cholecalciferol). Although humans utilize both sources, pigs discriminate in their metabolism and more readily utilize cholecalciferol. Cholecalciferolis produced in the photochemical conversion of 7-dehydrocholesterol within the skin of animals when exposed to sunlight or a synthetic UVb light source. One IU of vitamin D is defined as .025 μg of cholecalciferol. Both vitamin D₂ and vitamin D₃ are hydroxylated in the liver to the 25-hydroxy forms (25(OH)D₂ and 25(OH)D₃). This metabolite of vitamin D is the main circulating form in the blood and acts as a clinically useful marker for vitamin D status. 25(OH)D₃ is then hydroxylated again in the renal tubules within the kidney to 1,25(OH)₂D₃ by the 25(OH)D 1α-hydroxylase enzyme or to 24,25(OH)₂D₃ by the 24α-hydroxylase enzyme. The 1,25(OH)₂D₃ form is the most potent metabolite that is used in the regulation of Ca and P absorption across the intestinal wall. The vitamin D receptor (VDR) transcription factor acts as the major mediator between the metabolite 1,25(OH)₂D₃ and its target cell. Research shows that both the 1,25 and the 24,25 metabolites are important for proper bone formation. Additionally, the presence of VDRs has been reported within macrophages and activated T and B lymphocytes, insinuating a relationship between vitamin D and immune function. Also, the hydroxylated D₃ metabolites are viewed as hormones because they act according to established criteria for hormones, which includes acting on mucosal cells of the small intestine to cause the formation of calcium-binding proteins. These proteins facilitate Ca and Mg absorption and influence P absorption. Together with a parathyroid hormone and calcitonin, they maintain a Ca and P homeostasis in the body.

 

Relatively little information is available on the normal concentration of cholecalciferol or its metabolite 25(OH)D₃ in weanling pigs. Results of recent analyses from serum samples collected by Abilene Animal Hospital (Abilene, KS) and Iowa State University and assayed at Heartland Assays Inc. (Ames, IA) indicate that pigs have lower than expected concentrations of vitamin D at weaning. These concentrations are considered inadequate for bone mineralization and overall health in young pigs. Bone microfractures have been documented in cohorts of these pigs sampled for serum analysis. These microfractures could represent a subclinical form of rickets. We hypothesized that microfractures could result in slowed growth of piglets during the farrowing and nursery phase; furthermore, low-serum vitamin D concentrations may also affect muscle function and the immune system. A prior pilot study has verified that oral dosing of vitamin D₃ to pigs shortly after birth can increase serum 25(OH)D₃ at weaning, but growth performance was not measured. Therefore, this trial was conducted to determine the effects of oral vitamin D₃ dosage on growth performance, serum 25(OH)D₃, and bone ash of pre- and postweaning pigs.

 

Procedures

The protocol in this experiment was approved by the Kansas State University Institutional Animal Care and Use Committee. The study was performed at the K-State Swine Teaching and Research Center in Manhattan, KS.

 

A total of 270 pigs (PIC 327 × 1050; initially 2 d of age) from 29 litters were used in a 52-d study to determine the effects of oral vitamin D₃ dosage on subsequent pre- and postweaning pig performance, serum 25(OH)D₃, and bone ash concentrations. Pigs were allotted to treatments in a randomized complete block design with litter and matched set within litter functioning as the blocks. Sow gestation and lactation diets were corn-soybean meal-based with 40% DDGS in gestation and 20% DDGS in lactation and contained 625 IU vitamin D₃ per lb (Table 1).

 

Shortly after farrowing, pigs were allotted to 1 of 3 oral vitamin D3 treatments: (1) a control treatment with 1 mL of a peanut oil- and ethanol-based liquid carrier without vitamin D₃, (2) 1 mL with 40,000 IU vitamin D₃ in a peanut oil- and ethanol-based liquid carrier, or (3) 1 mL with 80,000 IU vitamin D3 in a peanut oil- and ethanolbased liquid carrier. Pigs were allotted to treatments on 2 different days (d 0 or 2 of the trial) during the week of farrowing. This allowed pigs to be placed on test at either 1 or 2 d after farrowing. To perform the allotment, pigs were weighed on their own respective allotment days and 3 pigs closest in weight within a litter were considered a matched set. The numbers of matched sets per litter were variable depending on the number of pigs born and weight variation; however, gender was balanced across treatments. Within each litter, 1 matched set closest to the average litter weight was then bled by jugular venipuncture to determine initial 25(OH)D₃ levels. Each pig was eartagged for identification, and pigs within each matched set were randomly allotted and dosed with 1 of the 3 oral treatments. No cross-fostering was performed on treatment pigs. Necropsies were performed on the majority of pigs that died during the lactation period. Neither creep feed nor other supplements were provided except the respective vitamin D₃ dosage. Management of all pigs, including processing methods, was similar throughout the trial and consistent with standard farm procedures.

 

After the initial 2 allotment days, all pigs were individually weighed on single days, which were 10, 18, and 20 d after the first pigs were placed on test (d 0). On d 10, pigs were weighed, and the same matched set of pigs bled previously within each litter were bled again for 25(OH)D₃ concentrations via jugular venipuncture. On d 18, pigs were again weighed, and based on this weight a total of 6 matched sets were selected for a necropsy on d 19. On d 20, remaining pigs were weighed and weaned into a nursery facility. After pigs were placed in their respective nursery pens, blood was again collected from those pigs previously sampled for serum 25(OH)D₃ concentrations.

 

For the nursery phase (d 20 to 52), pigs were penned by treatment. Sets of pens were blocked to minimize the effect of location. Pigs were assigned to a set of pens, maintaining the integrity of the initial matched sets within a pen set. There were 6 or 7 pigs per pen and a total of 12 pens for the control treatment and the 40,000 IU treatment and 11 pens for the 80,000 IU treatment. All pigs that were allotted on d 0 and alive at d 20 were evaluated in the nursery phase. Pens contained a 4-hole, dry self-feeder and nipple waterer to allow for ad libitum access to feed and water. All pigs were fed a common 3-phase dietary program. Phase 1 diets (SEW and transition diets) were fed from d 20 to 25 and were fed in pelleted form. Phase 2 and 3 diets were fed from d 25 to 39 and d 39 to 52, respectively, and were fed in meal form (Table 2).

 

During the nursery phase, pig weights were recorded on d 20, 25, 32, 39, 46, and 52. Feed disappearance was recorded during the nursery stage and used with pig weights to determine ADG, ADFI, and F/G. Pigs selected for serum 25(OH)D₃ concentrations were bled again on d 30 and 52. On d 35, 12 pigs were selected (6 from the control treatment and 6 from the 80,000 IU vitamin D₃ treatment) for necropsy.

 

Necropsies were conducted at the K-State College of Veterinary Medicine. All necropsies performed were in compliance with the college’s standard operating procedures. On d 19, pigs were bled via jugular venipuncture and were euthanized with an intravenous overdose of sodium pentobarbital (Fatal Plus, Deerborn, MI). Both femurs and the 2nd and 3rd ribs on both sides were removed to determine bone ash content. The 4th ribs and tibias were removed for histopathology examination. On d 35, 12 more pigs were selected for necropsy with 6 chosen from both the control and 80,000 IU vitamin D₃ treatment groups. Tissue collection procedures were similar to those performed on d 19.

 

Blood samples were collected on prior to dosing and on d 10, 20, 30, and 52 (along with the blood samples from the necropsy pigs on d 19 and 35). All samples were collected in serum separator tubes and were refrigerated for at least 6 h after collection. Blood was centrifuged at 2,800 rpm for 25 min. Serum was extracted and stored in 2-mL vials and frozen in a freezer at -20ºC. All 25(OH)D₃ testing was performed by Heartland Assays Inc.

 

Statistical analysis conducted for each portion of the study was performed using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). For the preweaning period, the growth data were analyzed as a randomized complete block design. Individual pig was the experimental unit and litter and matched sets within litter were included as blocking factors in the statistical model. Only pigs that completed the full lactation period (d 0 to 20) were used in this analysis. Nursery growth performance data were analyzed as a randomized complete block using pen as the experimental unit and pen set as a blocking factor. Bone ash results were analyzed using the PROC MIXED procedure of SAS with individual pig as the experimental unit. Serum 25(OH)D3 results were analyzed using the repeated measures function of SAS to determine the effect of treatment on serum concentrations over time and the treatment × time interactions. Linear and quadratic effects were also evaluated for increasing vitamin D₃ dosage.

 

Results and Discussion

In the lactation phase (d 0 to 20), no significant differences were observed (P > 0.14) for ADG (Table 3), but d 20 BW was numerically increased by 0.3 lb/pig for pigs previously given oral vitamin D₃. During the nursery phase (d 20 to 52), previous oral vitamin D₃ dosage did not affect (P > 0.29) ADG, ADFI, or F/G (Table 4); however, similar to the lactation phase, pigs previously dosed with either 40,000 or 80,000 IU vitamin D₃ were numerically heavier (0.5 lb/pig) at the end of the nursery phase.

 

Prior to vitamin D₃ supplementation, initial serum 25(OH)D₃ concentrations were similar (P = 0.99) among all pigs (Table 5). A vitamin D₃ dose × day interaction (P < 0.01) was observed for serum 25(OH)D₃. The interaction was the result of serum 25(OH)D₃ increasing (quadratic, P < 0.01) over time with the greatest values observed on d 10 for pigs dosed with vitamin D₃ (Figure 1). Pigs orally dosed with vitamin D₃ had greater serum 25(OH)D₃ on d 10 (quadratic, P < 0.01), 20 (quadratic, P < 0.01), and 30 (linear, P < 0.01) with concentrations similar to control values on d 52 (P > 0.36).

 

Bone ash from femurs of pigs euthanized on d 19 (Table 6) showed no effect (P > 0.46) of vitamin D₃ dosage, but 2nd rib ash content tended (linear P < 0.09) to decrease as oral vitamin D₃ dosage increased. No differences were found in bone mineralization of femurs or the 2nd rib collected on d 35 (P > 0.47).

 

Histopathologic analysis revealed all ribs from both collection days were similar in progression of chondrocytes through the normal maturation zones. The zones had a normal even, abrupt transition to primary spongiosa, which undergoes remodeling to form the secondary spongiosa and trabecular bone. The growth plates were uniform in width across their length except one rib that was collected from a pig dosed with 40,000 IU vitamin D₃. For this pig, the physis was uneven and there were irregular, somewhat rectangular plugs of hypertrophied zone cartilage extending into the metaphysis. On the metaphyseal surface, and lateral to the plugs, there was normal formation of primary spongiosa that was remodeled to secondary spongiosa. The tibial physis of this pig also was uneven with a few V-shaped plugs of cartilage extending toward the metaphysis. One potential explanation for this phenomenon is trauma that may have occurred during lactation. This pig also showed swelling in its right hip and, upon visual evaluation during necropsy, abnormal mineralization of its right femur (not ashed). The presentation of this pig is consistent with injury by the sow during lactation. All tibias collected for histopathologic analysis were categorized as having normal maturation zones and growth plates as well as typical primary spongiosa formation.

 

In summary, pigs in this study initially started with similar concentrations of 25(OH) D₃ prior to dosing. On d 10, 20, and 30, serum concentrations were dependent on the dosage of supplemental vitamin D₃; however, by d 52, serum concentrations had returned to values similar to that of control pigs. This might suggest that the standard addition of 625 IU vitamin D₃/lb of vitamin premix supports circulating 25(OH)D₃ concentrations of approximately 15 ng/mL in the nursery pig.

 

Oral vitamin D₃ dosage had no significant effect on growth performance throughout the duration of the study. Yet pigs dosed with either 40,000 IU or 80,000 IU vitamin D₃ weighed numerically more than that of their control contemporaries at weaning (d 20) and again at the end of the study (d 52). Also, no differences were observed for percentage bone ash or histopathologic analysis of bone samples collected on d 19 or 35. But it should be pointed out that percentage ash values, regardless of treatment, were much lower than the expected range of values (approximately 56%)6 for mineral content as a percentage of dry fat-free bone. Perhaps this is because of the young age of the pigs on trial and the fact that most reference sources on the topic have been sampled from older pigs. Even so, oral vitamin D₃ at d 2 postfarrowing failed to increase percentage of ash in the nursery pig.

 

Although no growth performance differences were observed in this study, more research should be conducted with varying genotypes and herd health statuses to determine other possible links related to vitamin D responses. More work also should be completed in the area of Ca, P, and vitamin D interactions to determine optimal concentrations of these nutrients in feed for optimal mineralization of bone tissue, muscle function, and performance of growing swine.

 

¹ Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University.

² Abilene Animal Hospital, PA, Abilene, KS.

³ Biomedical Sciences, College of Veterinary Medicine, Iowa State University.

⁴ Heartland Assays Inc., Ames, IA.

⁵ Veterinary Diagnostic and Production Animal Medicine, Iowa State University.

⁶ Lewis and Southern. 2002. Swine Nutrition. 2nd ed. CRC Press, Boca Raton, FL.

 

 

 

 

Table 1. Composition of sow diets (as-fed basis)

 

******TABLE 1 GOES HERE******

 

¹ Natuphos 600, BASF, Florham Park, NJ. Provided 272 phytase units per pound of diet.

² Phytase provided 0.11% available P to both gestation and lactation diets.

³ Provided 625 IU vitamin D per pound of diet.

 

Table 2. Composition of nursery diets (as-fed basis)

 

******TABLE 2 GOES HERE******

 

¹ During Phase 1 (d 20 to 25) in the nursery, SEW and transition diets were allotted at 1 and 3 lb/pig, respectively (4 lb total per pig).

² Natuphos 600, BASF, Florham Park, NJ. Provided 449 phytase units per pound of diet in Phase 2 and 3 rations.

³ Ken Gest, Kemin Industries Inc., Des Moines, IA.

⁴ Provided 625 IU vitamin D per pound of diet.

 

Table 3. Effects of oral vitamin D3 dose on preweaning growth performance growth^1,2

 

******TABLE 3 GOES HERE******

 

¹ A total of 270 pigs from 29 litters (PIC 327 × 1050) were used in a 20-d preweaning study to determine the effects of oral vitamin D₃ dose at 2 d of age on growth performance.

² Data were analyzed using performance records from pigs that survived through weaning, d 20.

³ Initial refers to pigs placed on test on both d 0 and d 2 of the trial. Pigs were placed on test at 1 or 2 d postfarrowing. Pig days were adjusted to account for differences in trial starting day for calculating ADG from d 0 to 10.

⁴ Six pigs per treatment (6 matched sets) were removed on d 19 for necropsy.

 

Table 4. Effects of oral vitamin D3 dose on nursery pig growth¹

 

******TABLE 4 GOES HERE******

 

¹ A total of 235 weaned pigs (PIC 327 × 1050) initially 21 d of age were used in a 32-d nursery study to determine the effects of oral vitamin D₃ dose at 2 d of age on nursery pig growth and performance.

 

Table 5. Effects of oral vitamin D₃ dose on serum 25(OH)D₃ levels, ng/ml^1,2

 

******TABLE 5 GOES HERE******

 

¹ A total of 87 pigs or 29 pigs per treatment (1 matched set per litter) were bled prior to dosing (initial: includes pigs placed on test on both d 0 and 2) and 10 later in lactation and d 20, 30, and 52 in the nursery to determine serum 25(OH)D3 concentrations.

² Vitamin D₃ treatment × day effect (P < 0.01).

³ Initial refers to pigs placed on test on both d 0 and d 2 of the trial. Pigs were placed on test at 1 or 2 d postfarrowing. Pig days were adjusted to account for differences in trial starting day for calculating ADG from d 0 to 10.

 

Table 6. Effects of oral vitamin D₃ dose on bone ash, %¹

 

******TABLE 6 GOES HERE******

 

¹ A total of 18 pigs, 6 per treatment (6 matched sets), were necropsied and bone samples were collected on d 19; 12 pigs (6 control pigs and 6 pigs from the 80,000 IU vitamin D3 treatment) were necropsied on d 35.

 

******FIGURE 1 GOES HERE******

 

Figure 1. Effect of oral vitamin D₃ on serum 25(OH)D₃ concentrations.^1,2

¹ A total of 87 pigs or 29 pigs per treatment (1 matched set per litter) were bled on d 2 and 10 in lactation and d 20, 30, and 52 in the nursery to determine serum 25(OH)D₃.concentrations.

² Initial refers to pigs placed on test on both d 0 and d 2 of the trial. Pigs were placed on test at 1 or 2 d postfarrowing. Pig days were adjusted to account for differences in trial starting day for calculating ADG from d 0 to 10.

 

The Effects of High-Sulfate Water and Zeolite (Clinoptilolite) on Nursery Pig Performance¹

 

J.R. Flohr, M.D. Tokach, J.L. Nelssen, S.S. Dritz² , J.M. DeRouchey, R.D. Goodband, and N.W. Shelton

 

Summary

A total of 320 nursery pigs (PIC 1050 barrows) were used in a 24-d study to determine the effects of high-sulfate water and dietary natural zeolite on growth performance and fecal consistency of nursery pigs. Eight treatments were arranged as a 2 × 4 factorial with 2 water treatments (control or water with 3,000 ppm sodium sulfate), and 4 dietary zeolite concentrations (0, 0.25, 0.5, and 1.0%). Water treatments remained the same from d 0 to 24 and all diets were fed in 2 phases, with diets containing zeolite having the same inclusion rate in both phases. Phase 1 diets were fed in a pellet form from d 0 to 10 after weaning, with Phase 2 diets fed in meal form from d 10 to 24. Fecal samples were collected on d 5, 9, 16, and 23. These samples were visually assessed and scored on a scale of 1 to 5 to determine consistency of the fecal samples then analyzed for DM.

 

From d 0 to 10, neither sulfate addition to the water nor zeolite influenced ADG, ADFI, or F/G. Dietary treatment had no effect on fecal consistency; however, pigs drinking control water had a lower (P < 0.01) fecal score (fewer visual observations of scours) than pigs drinking high-sodium sulfate water. From d 10 to 24, pigs drinking control water had improved (P < 0.01) ADG, ADFI and F/G compared with pigs drinking high-sodium sulfate water. Dietary zeolite increased (linear, P < 0.01) ADG and ADFI, but did not affect fecal scores. Similar to Phase 1, pigs drinking control water had lower (P < 0.01) fecal scores, indicating less scouring compared with pigs drinking the high-sodium sulfate water. Dry matter analysis indicated that dietary zeolite had no effect on fecal DM, but high-sodium sulfate water decreased (P < 0.01) total DM content of fecal samples in both Phase 1 and the first collection in Phase 2, but not on d 23, the final collection.

 

Overall (d 0 to 24), increasing zeolite increased (linear, P < 0.05) ADG and ADFI, but F/G was not affected. Pigs drinking high-sulfate water had decreased (P < 0.01) ADG and ADFI and poorer (P < 0.01) F/G compared with pigs drinking control water. In conclusion, pigs drinking water with 3,000 ppm sodium sulfate had decreased ADG, ADFI, and poorer F/G from d 10 to 24 and for the overall trial. These pigs also had an increased incidence of scouring as measured by lower fecal DM compared with pigs drinking control water. Although zeolite improved ADG and ADFI, it did not influence fecal consistency.

 

Key words: nursery pig, sulfate, water, zeolite

 

Introduction

Zeolites are microporous aluminosilicate minerals composed of alkali and alkaline earth cations along with small amounts of other elements. The zeolite molecules are arranged in 3-dimensional structures that create interconnected channels capable of trapping molecules of proper dimensions similar to a sieve. Zeolite molecules can also bind and release specific molecules by adsorption or ion exchange. In industrial operations, zeolites have been used as detergents because of their ability to bind with water and other molecules. In agriculture, zeolites frequently have been used to reduce odor because of their ability to bind with ammonia. Although research is limited, previous results (Shurson et al., 1984³ ) observed in a study comparing synthetic zeolite and natural zeolite as growth promoters in late nursery phases that the synthetic zeolite (zeolite A) was relatively ineffective as a growth promoter in nursery pig diets. Synthetic zeolite was thought to become disassociated in the acidic environment of the digestive system; however, naturally occurring zeolite (clinoptilolite) was effective in its ammonia-binding capabilities and more stable in the gut, yet when it exceeded 5% of the diet, overall growth performance decreased compared with the control treatment. Perhaps by using its sieving capabilities, natural zeolite can bind with non-nutritive components of the diet and decrease their ability to cross the gut wall, but when inclusion rates become too high, it may bind with required nutrients and decrease pig performance.

 

Producers, especially those in the upper Midwest, have recently observed increased incidence of scours. Scours typically are associated with health and disease challenge along with the stress that accompanies weaning. Water quality and high-protein diets can also contribute to diarrhea and loose feces. In addition, increased incidence of scouring could be due to high sodium sulfate concentrations within groundwater supplies. Research by Anderson and Stothers (1978)⁴ has shown that sulfates act as a natural laxative and can cause an increased occurrence of scours, but without significant detrimental effects on growth performance. Whether sulfates influence performance or not, they lead to increased cost in commercial swine production because producers treat the pigs with antibiotics in an attempt to decrease scour symptoms.

 

Therefore, our objectives for the study were to evaluate the effects of high-sulfate water on the performance and fecal consistency of newly weaned pigs and to determine whether a natural zeolite (clinoptilolite) could improve fecal consistency and growth of pigs drinking high-sulfate water.

 

Procedures

The protocol for this experiment was approved by the Kansas State University Institutional Animal Care and Use Committee. The study was conducted at the K-State Segregated Early Weaning Facility in Manhattan, KS.

 

A total of 320 nursery pigs (PIC 1050 barrows, initially 11.9 lb, and 21 d of age) were used in a 24-d trial to evaluate the effects of high-sulfate water and dietary zeolite (clinoptilolite) on growth performance. Pigs were weighed and allotted to 1 of 8 treatments arranged in a 2 × 4 factorial with main effects of water source (control or water containing 3,000 ppm sodium sulfate) and dietary zeolite (0, 0.25, 0.5, and 1.0%). There were 5 pigs per pen and 8 pens per treatment. Pigs were provided unlimited access to feed and water by way of a 4-hole dry self-feeder and a cup waterer in each pen (5 ft by 5 ft). For the sodium sulfate water treatment, sodium sulfate was mixed in a stock solution and administered in the water supply (Manhattan, KS, municipal water source) of the corresponding pens by a medicator (Dosatron; Dosatron International Inc., Clearwater, FL) at the rate of 1:10 for a calculated inclusion rate of 3,000 ppm of sodium sulfate. All diets were fed in 2 phases (Table 1), and the dietary zeolite concentration was the same in both phases. Phase 1 diets were fed in a pellet form from d 0 to 10 after weaning. Phase 2 diets were fed in a meal form from d 10 to 24. Average daily gain, ADFI, and F/G were determined by weighing pigs and measuring feed disappearance on d 5, 10, 17, and 24.

 

Chemical composition of the natural zeolite (clinoptilolite) used in the experiment is shown in Table 2. Water samples were collected for both the control water supply with no sodium sulfate and the water treatment with 3,000 ppm sodium sulfate. Samples were analyzed by Servi-Tech Laboratories, Dodge City, KS, and were analyzed for sodium, sulfate, and total dissolved solids (Table 3).

 

Fecal samples were collected on d 5, 9, 16, and 23. The samples were collected from 3 randomly selected pigs per pen for a total of 24 samples per treatment. Immediately after collection, the samples were individually scored by 5 individuals trained to determine fecal consistency; therefore, 15 consistency scores were made for each pen and an average score was reported for the pen. The scale used for assessing fecal consistency was based on a numerical scale of 1 to 5, where 1 represented a hard, dry fecal pellet, 2 represented a firm formed feces, 3 represented soft moist feces that retained its shape, 4 represented soft unformed feces that assumes the shape of its container, and 5 represented a watery liquid that can be poured. After scoring, samples were analyzed for DM. A 2-stage DM procedure was used. The first stage consisted of drying the complete sample in a 122ºF oven for 24 h. Afterward, the samples were allowed to cool, then were ground into a powder. In the second stage, 1 g of the ground sample was placed in a crucible and dried in a 212ºF oven for 24 h. The initial DM value was then multiplied by the second to determine a total percentage DM.

 

Nursery pig growth performance was analyzed as a 2 × 4 factorial with main effects of water treatment and dietary zeolite using the MIXED procedure of SAS (SAS Institute, Inc., Cary, NC). Pen was designated as the experimental unit and contrast statements were used to determine effects of water treatment, linear and quadratic effects of dietary zeolite, and their interactions.

 

For fecal scores and fecal DM, repeated measures analysis was conducted using the MIXED procedure of SAS. Pen was the experimental unit and again the fixed effects were water treatment and dietary zeolite. Contrast statements were used to evaluate: (1) linear and quadratic effects of increasing zeolite, (2) linear and quadratic effects over time (collection days), (3) water × day interactions, (4) diet × day interactions, and (5) water × diet × day interactions.

 

Results and Discussion

During Phase 1 (d 0 to 10), a water source × zeolite interaction (linear, P < 0.04) was observed for ADFI (Tables 4 and 5), which occurred because ADFI increased as zeolite increased for pigs drinking high-sulfate water, but decreased with increasing zeolite for pigs drinking control water. No other interactions were observed. Sulfate addition to the water and dietary zeolite did not influence ADG, ADFI, or F/G from d 0 to 10 (Table 5).

 

During Phase 2 (d 10 to 24), increasing zeolite improved (linear, P < 0.01) ADG and ADFI, with no effect on F/G. Also, ADG, ADFI, and F/G were poorer (P < 0.02) for pigs drinking high-sulfate water compared with those drinking control water.

 

Overall (d 0 to 24), increasing zeolite increased (linear, P < 0.05) ADG and ADFI, but F/G was not affected. Pigs drinking high-sulfate water had decreased (P < 0.01) ADG and ADFI and poorer (P < 0.01) F/G compared with pigs drinking control water.

 

A water × day interaction (P < 0.01) was observed as lower fecal scores over time for pigs drinking high-sodium sulfate water, which indicated their feces became firmer over time. In contrast, fecal consistency scores for the control water group remained consistent throughout the length of the trial.

 

Dietary zeolite did not influence fecal consistency scores (Tables 6 and 7); however, fecal samples were looser (P < 0.01) for pigs drinking high-sodium sulfate water compared with control pigs.

 

Dietary zeolite had no effect on fecal DM content (Tables 8 and 9) in either Phase 1 or 2, but pigs drinking high-sodium sulfate water had decreased (P < 0.01) DM content compared with control pigs. A water × day interaction (P < 0.01) occurred, which was the result of an increase in fecal DM content of pigs on the sodium sulfate water treatment over time, even though pigs on the control water treatment had consistent DM contents throughout the length of the study.

 

In conclusion, dietary zeolite appeared to have no impact on the fecal consistency of the pigs drinking high-sodium sulfate water, but the improvement in ADG and ADFI with the addition of zeolite during Phase 2 was interesting and unexpected. Although we are unsure of the biological reason for the improvement in growth performance, it may relate to the sieving properties of zeolite and its contribution to gut microbiology or its ability to bind with anti-nutritional aspects of feed ingredients and reduce their absorption. More research should be conducted to confirm the findings of this study and to determine whether zeolite should be included in nursery pig diets.

 

As for high-sodium sulfate water, the results from this trial agree with previous research demonstrating its negative effects on fecal consistency. Over time, fecal consistency appears to become better (firmer feces) as pigs adapt to the water; however, our calculated concentration of 3,000 ppm sodium sulfate negatively affected performance.

 

 

 

 

 

¹ The authors would like to thank St. Cloud Mining Co., Truth or Consequences, NM, for providing the zeolite used in this study.

² Food Animal Health and Management Center, College of Veterinary Medicine, Kansas State University.

³ G. C. Shurson, P. K. Ku, E. R. Miller and M. T. Yokoyama. 1984. Effects of Zeolite a or Clinoptilolite in Diets of Growing Swine. J. Anim. Sci. 59:1536-1545.

⁴ D. M. Anderson and S. C. Stothers. Effects of saline water in sulfates, chlorides and nitrates on the performance of young weanling pigs. J. Anim. Sci. 47:900-907.

 

Table 1: Diet composition (as-fed basis)

 

******TABLE 1 GOES HERE******

 

¹ Phase 1 diets were fed from d 0 to 10.

² Phase 2 diets were fed from d 10 to 24.

³ Nutra-Flo Company, Sioux City, IA.

⁴ Phyzyme 600, Danisco Animal Nutrition, Carol Stream, IL. Provided 354 and 463 FTU/lb of diet, respectively.

5⁵ Kem-gest, Kemin Industries Inc., Des Moines, IA.

⁶ Zeolite, St. Cloud Mining Company, Truth or Consequences, NM, replaced corn to provide 0, 0.25, 0.50, and 1% zeolite.

⁷ Zeolite calculated trace mineral content was added to the calculated trace mineral levels within each respective dietary regimen.

 

Table 2: Chemical composition of zeolite (clinoptilolite)¹

 

******TABLE 2 GOES HERE******

 

¹ Chemical composition performed by used of x-ray fluorescence and conducted at St. Cloud Mining Co., Truth or Consequences, NM.

 

 

Table 3: Analyzed composition of water¹

 

******TABLE 3 GOES HERE******

 

¹ Water samples were analyzed by Servi-Tech Laboratories, Dodge City, KS.

² City municipal water, Manhattan, KS.

³ Calculated mix of 3000 ppm was delivered into water supply at a rate of 1 to 10 by Dosatron medicators (Dosatron International Corp., Clearwater, FL).

 

Table 4: Effects of high-sulfate water and dietary zeolite (clinoptilolite) on nursery pig performance¹

 

******TABLE 4 GOES HERE******

 

¹ A total of 320 weanling pigs (PIC 1050 barrows, initial BW of 11.9 lb and 21 d of age) were used with 5 pigs per pen and 8 pens per treatment.

 

Table 5: Main effects of high-sulfate water and dietary zeolite (clinoptilolite) on nursery pig performance¹

 

******TABLE 5 GOES HERE******

 

¹ A total of 320 weanling pigs (PIC 1050 barrows, initial BW of 11.9 lb and 21 d of age) were used with 5 pigs per pen and 8 pens per treatment.

 

Table 6: The interactions of high-sulfate water and dietary zeolite (clinoptilolite) on fecal consistency^1,2,3,4

 

******TABLE 6 GOES HERE******

 

¹ A total of 792 fecal samples were collected (192 per collection day; fecal samples were collected on d 5, 9, 16, and 23). Three samples were taken per pen and were scored by 5 trained individuals; those 15 scores were then averaged and reported as pen means for each collection day.

² Three samples were collected randomly from 3 pigs per pen, and samples were scored on a numerical scale from 1 to 5.

³ Scoring scale guidelines: 1 = dry firm pellet, 2 = firm formed stool, 3 = soft stool that retains shape, 4 = soft unformed stool that takes shape of container, 5 = watery liquid that can be poured.

⁴ Water × diet × day interaction (P = 0.18).

 

Table 7: Main effects of high-sulfate water and dietary zeolite (clinoptilolite) on fecal consistency scores^1,2,3,4

 

******TABLE 7 GOES HERE******

 

¹ A total of 792 fecal samples were collected (192 per collection day; fecal samples were collected on d 5, 9, 16, and 23). Three samples were taken per pen and were scored by 5 trained individuals; those 15 scores were then averaged and reported as pen means for each collection day.

² Three samples were collected randomly from 3 pigs per pen, and samples were scored on a numerical scale from 1 to 5.

³ Scoring scale guidelines: 1 = dry firm pellet, 2 = firm formed stool, 3 = soft stool that retains shape, 4 = soft unformed stool that takes shape of container, 5 = watery liquid that can be poured.

⁴ Day main effect (P ≤ 0.01)

 

Table 8: The interactions of high-sulfate water and dietary zeolite (clinoptilolite) on fecal dry matter, %^1,2,3

 

******TABLE 8 GOES HERE******

 

¹ A total of 792 fecal samples were collected (192 per collection day).

² Three samples were collected randomly from 3 pigs per pen, and samples were dried using a 2-stage drying method.

³ Water × diet × day interaction (P = 0.41)

 

Table 9: The main effects of high-sulfate water and dietary zeolite (clinoptilolite) on fecal DM, %^1,2,3

 

******TABLE 9 GOES HERE******

 

¹ A total of 792 fecal samples were collected (192 per collection day; fecal samples were collected on d 5, 9, 16, and 23).

² Three samples were collected randomly from 3 pigs per pen, and samples were dried using a 2-stage drying method.

³ Day main effect (P < 0.01).

 

Effects of Feeding Copper and Feed-Grade Antimicrobials on the Growth Performance of Weanling Pigs

 

R. G. Amachawadi¹ , N. W. Shelton, M. D. Tokach, H. M. Scott¹¹ , R. D. Goodband, J. M. DeRouchey, J. L. Nelssen, and T. G. Nagaraja¹

 

Summary

A total of 240 weanling pigs (34 d of age with an average body weight of 17.1 lb) were used in a 35-d growth trial to compare the growth performance effects of copper (Cu) and feed-grade antimicrobials. The 6 dietary treatments were arranged in a 2 × 3 factorial with 2 added Cu levels (basal level of 16.5 ppm or basal + 125 ppm from copper sulfate) and 3 antimicrobial treatments including a control, chlortetracycline (CTC; Alpharma, Fort Lee, NJ) at 500 g/ton (10 mg/kg BW), and tylosin (Tylan; Elanco Animal Health, Greenfield, IN) at 100 g/ton. Each treatment had 8 pens with 5 pigs per pen. Treatments were allotted to pen in a randomized complete block design, with location within the barn serving as the blocking factor. Following the brief acclimatization period prior to starting the experiment (13 d), pigs were fed dietary treatments for 21 d followed by another 14 d on the control diet to examine any carryover effects. No significant copper × antimicrobial interactions were observed (P > 0.07) for any pig performance response. From d 0 to 21, pharmacological Cu tended to increase (P < 0.07) both ADG and ADFI compared with pigs provided basal levels of Cu. Dietary CTC inclusion increased (P < 0.01) ADG and tended to improve (P < 0.09) ADFI and F/G over pigs not fed diets with CTC. Dietary Tylan did not alter (P > 0.19) ADG, ADFI, or F/G compared with pigs provided the control diets. From d 21 to 35, pigs that previously had received pharmacological Cu tended to have lower (P < 0.06) ADG compared with those never receiving pharmacological Cu. Also, pigs previously receiving Tylan had lower (P < 0.01) ADG than those never receiving Tylan.

 

For the overall trial (d 0 to 35), adding Cu for the first 21 d had no impact (P > 0.32) on ADG, ADFI, or F/G. Similarly, Tylan did not influence (P > 0.30) pig performance. The benefits of CTC during the first 21 d led to a tendency for increased (P < 0.06) ADG and ADFI compared with those not receiving CTC. Overall, pharmacological Cu and antimicrobials may offer performance advantages when incorporated in nursery pig diets; however, that advantage will not increase and may be lost after Cu and/or antimicrobials are removed from diet.

 

Key words: antimicrobials, copper, growth promoters, nursery pig

 

Introduction

Pharmacological concentrations of Cu, fed as copper sulfate, are often used to enhance the growth performance in both weanling and growing pigs. Copper is often supplemented at pharmacological levels of 125 to 250 ppm to increase growth and feed intake in weanling pigs. The growth promotional effects of Cu are similar to that of antibiotics in that it alters the gut microbial flora, thereby reducing the fermentation loss of nutrients and suppressing pathogens. Studies done by Stahly et al. (1980)2 showed additive responses to subtherapeutic levels of Cu and antimicrobials; however, recent studies on the role of Cu and feed-grade antimicrobials on the growth performance of piglets are sparse. Therefore, the present study was conducted to evaluate the effects of Cu, chlortetracycline (CTC), and tylosin (Tylan) on the growth performance of weanling piglets.

 

Procedures

The protocol used in this experiment was approved by the Kansas State University Institutional Animal Care and Use Committee. The study was conducted at the K-State Segregated Early Weaning Research Facility in Manhattan, KS.

 

A total of 240 weanling pigs (34 d of age with an average body weight of 17.1 lb) were used in a 35-d growth trial to compare the growth performance effects of Cu and feedgrade antimicrobials. The 6 dietary treatments were arranged in a 2 × 3 factorial with 2 added Cu levels (basal level of 16.5 ppm or basal + 125 ppm from copper sulfate) and 3 antimicrobial treatments including a control, CTC at 500 g/ton (10 mg/kg BW), and Tylan at 100 g/ton. There were 8 pens per treatment with 5 pigs per pen. Each pen contained a 4-hole, dry self-feeder and a nipple waterer to provide ad libitum access to feed and water. All the pens had metal tri-bar flooring and provided approximately 3 ft² /pig. Pig weights and feed disappearance were recorded every week to calculate ADG, ADFI, and F/G. Treatments were allotted to pens in a randomized complete block design with location within the barn serving as the blocking factor, thereby ensuring that adjacent pens alternated among the treatment groups.

 

All pigs were placed on common starter diets for 13 d upon arrival to the nursery facility. The common diets did not contain any antimicrobials or pharmacological levels of Cu or Zn. After feeding a prestarter diet for the first 7 d of the 13-d pretest period, pigs were fed the phase 1 control diet for 6 d prior to the start of the experiment to become accustomed to the nutrient profile and create a constant environment for the enteric bacteria prior to starting the experiment. Treatment diets were then assigned for 21 d. The Phase 1 diet was utilized for 14 d, and the Phase 2 diet was used for the remaining 7 d of the 21-d antimicrobial portion (Table 1). To generate treatment diets, corn was replaced in the control diet with copper sulfate, Tylan, and/or CTC. After 21 d, all pigs were placed on the control diet from Phase 2 for 14 d to examine for any carryover effects from providing pharmacological Cu or antimicrobials.

 

Experimental data were analyzed as a 2 × 3 factorial using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Contrast statements were used to test the main effects of Cu addition and antimicrobial effects as well as the interactions. Additional contrast statements were used to compare the effects of CTC and Tylan compared with the controls. Random effects were used for barn as well as location within barn. Pen was the experimental unit for all data analysis. Statistics were considered significant at P < 0.05 and were considered tendencies at P < 0.10.

 

Results and Discussion

No significant copper × antimicrobial interactions were observed (P > 0.07) for any pig performance response in this study (Table 2). From d 0 to 21, adding pharmacological Cu to the diet tended to increase (P < 0.07) both ADG and ADFI compared with pigs provided basal levels of Cu. Dietary CTC inclusion increased (P < 0.02) ADG and d-21 BW. Adding CTC also tended to improve (P < 0.09) ADFI and F:G over pigs not provided diets with CTC. Dietary Tylan inclusion did not alter (P > 0.19) ADG, ADFI, or F/G compared with pigs provided the control diets.

 

As pigs were switched to the control diet (d 21 to 35), pigs that previously had received pharmacological Cu tended to have lower (P < 0.06) ADG compared with those never receiving pharmacological Cu. Also, pigs previously receiving Tylan had lower (P < 0.01) ADG compared with their control counterparts.

 

Throughout the entire 35-d study, Cu supplementation for the first 21 d had no impact (P > 0.32) on ADG, ADFI, or F/G. Similarly, addition of Tylan did not affect (P > 0.30) pig performance; however, the benefits of including CTC in the diet observed during the first 21 d led to a tendency for increased (P < 0.09) ADG, ADFI, and final BW compared with those not receiving CTC.

 

Overall, this study showed advantages to inclusion of 500 g/ton (10 mg/kg BW) of CTC in the diets of weanling pigs. After CTC was withdrawn from the feed, growth rate returned to control levels; however, the added gain achieved when CTC was fed was not lost. No advantages were observed for inclusion of Tylan. Several previous studies performed by K-State researchers have shown growth and feed intake advantages with pharmacological Cu. The current study showed a marginal pig performance response to Cu that was limited to the period when it was fed, followed by a lag in performance when pigs were switched back to basal Cu levels. Pharmacological Cu and antimicrobials may offer performance advantages when incorporated in nursery pig diets; however, that advantage will not increase and may be lost after Cu and/or antimicrobials are removed from diet.

 

 

 

¹ Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

² Stahly, T. S., G. L. Cromwell, and H. J. Monegue. 1980. Effects of dietary inclusions of copper and (or) antibiotics on the performance of weanling pigs. J. Anim. Sci. 51:1347-1351.

 

Table 1. Diet composition (as-fed basis)

 

******TABLE 1 GOES HERE******

 

¹ Pigs were fed Phase 1 from d 0 to 14.

² Pigs were fed Phase 2 from d 14 to 35.

³ Corn was replaced with chlortetracycline (CTC 50; Alpharma, Fort Lee, NJ) at 10 lb/ton, Tylan 100 (Elanco Animal Health, Greenfield, IN) at 1 lb/ton, and/or CuSO4 at 1 lb/ton to create treatment diets.

⁴ Phyzyme 600 (Danisco Animal Nutrition, St. Louis, MO) provided 450 FTU/lb, with a release of 0.13% available P.

 

Table 2. Effects of dietary antimicrobials and copper sulfate on weanling pig growth performance¹

 

******TABLE 2 GOES HERE******

 

¹ A total of 240 nursery pigs (PIC 1050 barrows, initially 17.1 lb) were used in a 35-d experiment with 8 pens per treatment.

² Antimicrobial regiments were applied from d 0 to 21. All pigs received the control diet from d 21 to 35.

³ Tylan (Elanco Animal Health, Greenfield, IN) was fed at 100 g/ton.

⁴ Chlortetracycline (Alpharma, Fort Lee, NJ ) was fed at 500 g/ton or approximately 10 mg/kg of body weight.

⁵ Copper was supplemented at 125 ppm above the basal level (16.5 ppm) from copper sulfate.

 

Effects of Liquitein on Weanling Pigs Administered a Porcine Circovirus Type 2 and Mycoplasma hyopneumoniae Vaccine Strategy¹

 

A. J. Myers, J. R. Bergstrom, M. D. Tokach, S. S. Dritz² , R. D. Goodband, J. M. DeRouchey, J. L. Nelssen, B. W. Ratlif³ , and D. M. McKilligan³

 

Summary

A total of 180 nursery pigs (PIC 327 × 1050, initially 12.6 ± 0.22 lb, and 19 ± 2 d of age) were used in a 35-d study to determine the effects of Liquitein and a porcine circovirus 2 (PCV2)/Mycoplasma hyopneumoniae (M. hyo) vaccine regimen on the growth performance of weanling pigs. Liquitein (TechMix, LLC Stewart, MN) is a watersoluble source of plasma and energy provided in the drinking water immediately after weaning. Pigs were randomly allotted to 1 of 4 treatments arranged in a 2 × 2 factorial with main effects of Liquitein (with or without) and PCV2/M. hyo vaccine regimen (vaccinates or non-vaccinates) with 5 pigs per pen and 9 pens per treatment. At weaning, pigs in the vaccinate group were given a full dose (2 mL) of ResprisureOne (Pfizer Animal Health, New York, NY) and Circumvent (Intervet/Schering-Plough Animal Health, Millsboro, DE). On d 21, pigs in the vaccinate group were administered a second full dose (2 mL) of Circumvent per label instructions. Liquitein was administered to the pigs via water medicators for the first 5 d after arrival to the nursery. No vaccine × Liquitein interactions occurred for ADG or F/G throughout the study. From d 0 to 5, non-vaccinated pigs had a tendency (P < 0.07) for increased ADG. From d 21 to 35, pigs previously administered Liquitein had greater ADFI (P = 0.05) than those not provided Liquitein; however, overall (d 0 to 35) Liquitein had no effects on growth performance. From d 0 to 35, vaccinated pigs had decreased (P < 0.01) ADG and ADFI compared with non-vaccinated pigs. In conclusion, administering Liquitein during the first 5 d in the nursery increased feed intake later in the nursery stage (d 21 to 35), but the response was not great enough to influence overall growth performance. Pigs administered the PCV2 and M. hyo vaccine regimen had decreased ADG and ADFI.

 

Key words: growth, liquid supplement, PCV2, weanling pig

 

Introduction

Weaning poses new challenges to the young pig such as a sudden change in diet and navigating social hierarchy. Consequently, postweaning pigs typically do not eat large quantities of feed in the first 24 to 72 h, which becomes problematic because sufficient nutrient intake is imperative to maintain gut integrity. To further compound the issue, anecdotal field reports have indicated that producers are having increased difficulty starting and maintaining weaned pigs on feed. These reports seem to have correlated with the wide-scale vaccination of weaned pigs for PCV2. Subsequent research trials at Kansas State University have indicated that PCV2 and M. hyo result in reduced nursery growth rate because of reduced feed intake (Kane et al., 2009⁴ ; Potter, 2010⁵ ).

 

Spray-dried animal plasma has been shown to improve both growth performance and feed intake in newly weaned pigs. Previous research has indicated that providing watersoluble plasma improved growth performance in newly weaned pigs (Steidinger et al., 2002)⁶ . Liquitein, a new product, recently has become available. Liquitein is a highdensity, ready-to-use source of plasma and digestible energy. It is shelf-stable and can be administered through water lines during the weaning period or other times of low feed intake and stress; therefore, our hypothesis was that providing nutrients through the water may be an effective method in combating postvaccination feed intake reduction. The objective of the study was to evaluate the effects of Liquitein and a PCV2 and M. hyo vaccine regimen on growth performance of nursery pigs.

 

Procedures

All practices and procedures used in these experiments were approved by the Kansas State University Institutional Animal Care and Use Committee.

 

A total of 180 nursery pigs (C327 ×1050, PIC, Hendersonville, TN) with an initial BW of 12.6 ± 0.22 lb and 19 ± 2 d of age were used in a 35-d study. Pigs were transported approximately 7 h (387 miles) from the sow farm to the K-State Segregated Early Weaning facility in Manhattan. The facility is a totally enclosed, environmentally regulated, mechanically ventilated barn with 40 12.9 ft² pens located over metal tribar flooring. Each pen housed 5 pigs and provided 3.2 ft² floor space per pig. Pigs were provided unlimited access to feed and water via a 4-hole dry self-feeder (17.3 in.) and 1-cup waterer.

 

After arrival to the segregated early weaning facility, pigs were allotted to 1 of 4 treatments arranged in a 2 × 2 factorial with main effects of Liquitein (with or without) and a PCV2 and M. hyo vaccine regimen (vaccinates or non-vaccinates) with 5 pigs per pen and 9 pens per treatment.

 

Liquitein was provided to the pigs via water medicators (Select Doser 640; Genesis Instruments, Elmwood, WI) set at a ratio of 50:1 (50 parts water to 1 part Liquitein) for the first 5 d after arrival to the nursery. Liquitein is a ready-to-use product, which allowed for the water medicator to draw Liquitein directly out of the container using peristaltic action to pump the product into the water. For all treatments, waterers were shut off until the pigs were allotted and placed into their respective pens for the experiment. After allotment, Liquitein treatment waterers were flushed until Liquitein appeared in the cup. For the duration of the Liquitein treatment, the container with the Liquitein was weighed daily and usage recorded. Lines distributing Liquitein were flushed daily to ensure a constant supply of product.

 

On d 0 (weaning), pigs in the vaccinate group were given a full dose (2 mL) each of ResprisureOne and Circumvent. Again on d 21, pigs in the vaccinate group were administered a second full dose (2 mL) of Circumvent. All vaccines were administered as separate intramuscular injections according to label directions.

 

Common 3-phase diets were fed for the duration of the trial (Table 1). Phase 1 diets were fed from d 0 to 5 and were in pellet form. Phase 2 and 3 diets were fed from d 5 to 21 and d 21 to 35, respectively, and were in meal form. Pigs were weighed on d 0, 2, 5, 7, 14, 21, 23, 25, and 35. Feed disappearance was measured on d 0, 1, 2, 3, 4, 5, 7, 14, 21, 22, 23, 24, 25, and 35. The frequent weighing and feed intake measurements were done to determine the immediate effects of vaccine administration. These measurements were used to calculate ADG, ADFI, F/G, and DMI.

 

Data were analyzed as a 2 × 2 factorial in a completely randomized design using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Pen was used as the experimental unit. When significant interactions (P < 0.05) were observed, least significant differences (LSDs) were the method used to separate the means. Results were considered significant at P ≤ 0.05

 

Results and Discussion

No vaccine × Liquitein interactions were observed for ADG or F/G for the duration of the study (Table 2).

 

One objective of our study was to evaluate ADG and ADFI immediately following administration of PCV2/M. hyo vaccination. To achieve this, we measured ADFI daily for 5 d after the first ResprisureOne and Circumvent (d 0) and second Circumvent vaccination (d 21). By d 3, pigs in the non-vaccinate group had increased (P < 0.05) ADFI compared with pigs in the vaccinate group (Figure 1). On d 4, a vaccine × Liquitein interaction (P < 0.05) was observed for ADFI. The interaction is a result of nonvaccinate pigs that did not receive Liquitein via their drinking water having increased ADFI compared with all other treatments. On d 7, a vaccine × Liquitein interaction (P < 0.05) for ADFI was observed where pigs in the vaccinate group who had not been previously administered Liquitein demonstrated increased ADFI compared with all other treatments. Average daily gain (data not shown) was affected by dehydration of the pigs during transportation (approximately 7 h from IL) to the facility.

 

From d 0 to 5, the period immediately following the first injection, a tendency (P = 0.07) was observed for pigs administered PCV2/M. hyo vaccine regimen to have decreased ADG compared with the non-vaccinate group. Although not significant, pigs administered Liquitein during this period had a numerical tendency (P = 0.11) for increased ADG and dry matter ADFI (DMFI).

 

From d 5 to 21 and 0 to 21, pigs administered PCV2/M. hyo vaccine regimen had decreased (P < 0.05) ADG compared with pigs in the non-vaccinate group. No significant differences were observed for Liquitein.

 

From d 21 to 25, pigs administered PCV2/M. hyo vaccine regimen had lower (P < 0.01) ADG and ADFI compared with pigs in the non-vaccinate group. As a result of the reduced feed intake, a tendency (P < 0.07) was measured for pigs administered PCV2/M. hyo vaccine regimen to have decreased F/G compared with pigs in the nonvaccinate group. No significant differences were observed for Liquitein.

 

The stress of diet change and vaccination could perhaps explain the decrease in growth performance seen from d 21 to 23 and 23 to 25, where pigs administered PCV2/M. hyo vaccine regimen had decreased (P < 0.05) ADG compared with pigs in the non-vaccinate group (Figure 2). On d 23 and 35, pigs in the non-vaccinate group had increased (P < 0.05) ADFI compared with pigs in the vaccinate group (Figure 3).

 

From d 21 to 35, pigs administered PCV2/M. hyo vaccine regimen had decreased (P < 0.01) ADG and ADFI compared with pigs in the non-vaccinate group. Pigs previously administered Liquitein had increased (P < 0.05) ADFI compared with pigs that were not provided Liquitein. Why pigs previously administered Liquitein had increased ADFI during this period is unclear; however, other studies that have evaluated Liquitein also have observed the same postadministration increase in ADFI (unpublished data). Several theories have evolved regarding the increase in ADFI observed postLiquitein administration. Perhaps Liquitein aids in maintaining the gut brush border, helping to boost immunity and consequently improve the piglet’s ability to handle the stress of the second vaccination.

 

Overall, no significant differences were observed for Liquitein. Pigs administered PCV2/M. hyo vaccine regimen had decreased (P < 0.01) ADG and ADFI compared with pigs in the non-vaccinate group.

 

In conclusion, administering Liquitein during the first 5 d in the nursery increased feed intake later in the nursery stage (d 21 to 35), but the response was not great enough to influence overall growth performance; however, pigs administered the PCV2 and M. hyo vaccine regimen had decreased ADG and ADFI.

 

¹ Appreciation is expressed to TechMix, LLC, Stewart, MN, for providing the Liquitein and partial financial support.

² Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

³ TechMix, LLC, Stewart, MN.

⁴ Kane, E. M., M. L. Potter, J. R. Bergstrom, S. S. Dritz, M. D. Tokach, J. M. DeRouchey, R. D. Goodband, and J. L. Nelssen. 2009. Effects of diet source and timing of porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae vaccines on post-weaning nursery pig performance. J. Anim. Sci. 87 (E-Suppl 3):7 (Abstr.).

⁵ Potter, M. L. 2010. Effects of Circovirus vaccination on immune responses, viral load, and growth performance of pigs under field conditions. PhD Diss. Kansas State University, Manhattan, KS.

⁶ Steidinger, M. U., R. D. Goodband, M. D. Tokach, J. L. Nelssen, S. S. Dritz, B. S. Borg, and J. M. Campbell. 2002. Effects of providing a water soluble globulin in drinking water and diet complexity on growth performance of weaning pigs. J. Anim. Sci. 80:3065-3072.

 

Table 1. Composition of diets (as-fed basis)¹

 

******TABLE 1 GOES HERE******

 

¹ A total of 180 nursery pigs (C327 ×1050, PIC, Hendersonville, TN) with an initial BW of 12.6 lb and 19 ± 2 d of age were used in a 35-d study.

² The SEW diet was a common diet fed the first 7 d postweaning and was in pellet form.

³ Phase 2 diets were fed from d 0 to 14 and were in meal form.

⁴ Phase 3 diet was a common diet fed from d 14 to 24 and was in meal form.

⁵ Phyzyme 600 (Danisco Animal Nutrition, St. Louis, MO) provided 231 FTU/lb, with a release of 0.10 available P.

 

Table 2. Effects of Liquitein and vaccine regimen on nursery pig performance¹

 

******TABLE 2 GOES HERE******

 

¹ A total of 180 nursery pigs ( PIC C327 ×1050) with an initial BW of 12.6 lb and 19 ± 2 d of age were used in a 35-d study to evaluate the effects of Liquitein and porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (M. hyo) vaccine regimen on growth performance of nursery pigs.

² Liquitein (Protein Resources; West Bend, IA) was added to the water lines at a ratio of 50:1. Liquitein disappearance was measured by weighing the container and was 1.10, 1.70, 5.20, 0.40, and 1.61 lb for days 1, 2, 3, 4, 5, respectively.

³ V × L = vaccine × Liquitein interaction.

⁴ Calculated by dividing ADG by DMI from both feed and liquid.

 

******FIGURE 1 GOES HERE******

 

Figure 1: Effects of Liquitein and PCV2/M. hyo vaccine strategy on ADFI.

 

******FIGURE 2 GOES HERE******

 

Figure 2: Effects of Liquitein and PCV2/M. hyo vaccine strategy on ADG. 

 

******FIGURE 3 GOES HERE******

 

Figure 3: Effects of Liquitein and PCV2/M. hyo vaccine strategy on ADFI. 

 

Effect of Total Lysine:Crude Protein Ratio on Growth Performance of Nursery Pigs from 15 to 25 lb¹

 

J. E. Nemechek, M. D. Tokach, S. S. Dritz² , R. D. Goodband, J. M. DeRouchey, J. L. Nelssen, and J. Usry³

 

Summary

A total of 282 nursery pigs (PIC TR4 × 1050, initially 15.9 ± 0.15 lb BW and 3 d postweaning) were used in a 28-d growth trial to evaluate the effects of total lysine:CP ratio, using fish meal as a source of non-essential N, on growth performance. Pigs were allotted to 1 of 6 dietary treatments. Each treatment had 5 replications with 7 pigs per pen and 2 replications with 6 pigs per pen. Pigs and feeders were weighed on d 0, 7, 14, 21, and 28 to calculate ADG, ADFI, and F/G. A 2-phase diet series was used with treatment diets fed from d 0 to 14 and a common diet fed from d 14 to 28. All diets were in meal form. The 6 total lysine:CP ratios were 6.79, 6.92, 7.06, 7.20, 7.35, and 7.51%. From d 0 to 14, there was a trend for increased (quadratic; P < 0.09) ADG with an increasing dietary total lysine:CP ratio up to 7.35%, with poorer performance in pigs fed the greatest lysine:CP diet. Increasing the total lysine:CP ratio tended to improve (quadratic; P < 0.09) F/G for pigs fed 7.35%, with poorer F/G as total lysine:CP ratio increased to 7.51%. When a common diet was fed (d 14 to 28), there was no difference in ADG or F/G. A response (quadratic; P < 0.04) was detected for ADFI due to an increase in ADFI from the pigs fed the intermediate diets (7.06 and 7.20% total lysine:CP) during the previous period. Overall (d 0 to 28), there was a trend (quadratic; P < 0.07) for increased ADG and ADFI caused by the numerically highest values from pigs fed a total lysine:CP ratio of 7.35% and the numerically lowest values from pigs fed a total lysine:CP ratio of 7.51%. Dietary treatment did not influence F/G for the overall trial. These results indicated that feeding total lysine:CP ratio greater than 7.35% may decrease growth performance of nursery pigs.

 

Key words: fish meal, lysine, nonessential amino acids, nursery pig

 

Introduction

Research has shown that increasing diet complexity improves growth performance of early nursery pigs; thus, these diets commonly contain specialty protein sources (fish meal, meat and bone meal, poultry meal, etc.). Although these products have been shown to positively influence growth compared with soybean meal, specialty protein sources are typically more expensive. The current trial was the fourth experiment of a series in which the primary objective was to determine the effect of replacing expensive specialty protein sources with crystalline amino acids (AA) on growth performance of nursery pigs. The first experiment was a lysine titration that established a standardized ileal digestible (SID) lysine requirement of 1.30% for nursery pigs from 15 to 25 lb. The next experiment completely replaced fish meal with high amounts of crystalline AA with no negative effects on growth performance. This established a low-CP, AA-fortified diet that could then be used in subsequent experiments. By removing specific AA from the previously established diet, the third trial demonstrated that valine, tryptophan, and a source of nonessential AA are required in the low-CP, AA-fortified diet. Thus, in addition to essential AA, pigs must also be supplied with a source of nonessential AA to achieve optimal growth. One method of measuring the nonessential AA relative to essential AA in the diet is by calculating the lysine:CP ratio. Research has shown that, in pigs, the total CP in muscle typically contains about 6.5 to 7.5% lysine, providing an approximate range of dietary lysine:CP ratios to be used in the current experiment. Therefore, the objective of this experiment was to evaluate the maximum total lysine:CP ratio required for optimal growth performance.

 

Procedures

The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment. The study was conducted at the K-State Swine Teaching and Research Center in Manhattan, KS.

 

A total of 282 nursery pigs (PIC TR4 × 1050, initially 15.9 ± 0.15 lb BW) were used in a 28-d growth trial to evaluate the effects of the total lysine:CP ratio, using fish meal as a source of non-essential N, on growth performance. Pigs were weaned at 19.5 ± 1.4 d of age and fed a common pelleted starter diet for 3 d. At weaning, pigs were allotted to pens by initial BW to achieve the same average weight for all pens. On d 3 after weaning, pens were allotted randomly to 1 of 6 dietary treatments; thus, d 3 after weaning was d 0 of the experiment. Each treatment had 5 replications with 7 pigs per pen and 2 replications with 6 pigs per pen. All pens (4 × 5 ft) contained a 4-hole, dry self-feeder and a nipple waterer to provide ad libitum access to feed and water.

 

A 2-phase diet series was used, with treatment diets fed from d 0 to 14 and a common diet fed from d 14 to 28. Treatment diets were corn-soybean meal-based and contained 10% dried whey and 1% soy oil. Diets were formulated to a predetermined SID lysine level of 1.30%. The 6 total lysine:CP ratios were 6.79, 6.92, 7.06, 7.20, 7.35, and 7.51% (Table 1). Crystalline L-Lysine, DL-Methionine, L-Threonine, L-Tryptophan, and L-Valine all increased as fish meal decreased to maintain minimum AA ratios of 58% Met & Cys:lysine, 64% threonine:lysine, 20% tryptophan:lysine, 52% isoleucine:lysine, and 70% valine:lysine. Large batches of the 6.79 and 7.51% total lysine:CP ratio diets were manufactured then blended at ratios of 80:20, 60:40, 40:60, and 20:80 to achieve the intermediate diets. The subsequent common diet for all the trials was a corn-soybean meal-based diet with no specialty protein sources, formulated to 1.26% SID lysine. All experimental diets were in meal form and were prepared at the K-State Animal Science Feed Mill. A subsample of all experimental diets was collected and analyzed for dietary AA by Ajinomoto Heartland LLC (Chicago, IL). Pigs and feeders were weighed on d 0, 7, 14, 21, and 28 to calculate ADG, ADFI, and F/G.

 

Experimental data were analyzed for linear and quadratic effects of increasing total lysine:CP ratio using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Pen was the experimental unit for all data analysis. Significant differences were declared at P < 0.05 and trends declared at P < 0.10.

 

Results and Discussion

From d 0 to 14, there was a trend for increased (quadratic; P < 0.09) ADG with increasing the total lysine:CP ratio up to 7.35%, with a 13% reduction in ADG when the ratio increased from 7.35 to 7.51% (Table 2). Increasing the total lysine:CP ratio tended to decrease (quadratic; P < 0.09) F/G for pigs fed 7.35%, with 7% poorer F/G as total lysine:CP ratio increased to 7.51%.

 

From d 14 to 28, there was no difference in ADG or F/G. A response (quadratic; P < 0.04) was observed for ADFI, which was the result of an increase in ADFI from the pigs fed the intermediate diets (7.06 and 7.20% total lysine:CP ratio) during the previous period (Table 2).

 

Overall (d 0 to 28), there was a trend (quadratic; P < 0.07) for increased ADG and ADFI caused by the numerically highest values from pigs fed a total lysine:CP ratio of 7.35% and the numerically lowest values from pigs fed a total lysine:CP ratio of 7.51% (Table 2). Dietary treatment did not influence F/G for the overall trial. These results indicated that feeding total lysine:CP ratio greater than 7.35% may decrease growth performance of nursery pigs. These data are consistent with reports of muscle composition of pigs which consist of approximately 6.5 to 7.5% lysine:CP.

 

¹The authors wish to thank Ajinomoto Heartland LLC, Chicago, IL, for providing the synthetic amino acids used in diet formulation and partial financial support.

² Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

³ Ajinomoto Heartland LLC, Chicago, IL.

 

Table 1. Diet composition (as-fed basis)

 

******TABLE 1 GOES HERE******

 

¹ Treatment diets were fed from d 0 to 14 and a common diet was fed from d 14 to 28.
² Phyzyme 600 (Danisco Animal Nutrition, St. Louis, MO) provided 5,231 FTU/lb, with a release of 0.10% available P.

 

Table 2. Evaluation of total lysine:CP ratio on growth performance in nursery pigs

 

******TABLE 2 GOES HERE******

 

¹  A total of 282 nursery pigs (PIC TR4 × 1050) were used in a 28-d growth trial to evaluate the effects of total Lys:CP ratio on growth performance. Values represent the means of 7 pens per treatment.

² Treatment diets were fed from d 0 to 14 and a common diet fed from d 14 to 28.

 

Effect of Replacing Commonly Used Specialty Protein Sources with Crystalline Amino Acids on Growth Performance of Nursery Pigs from 15 to 25 lb¹

 

J. E. Nemechek, M. D. Tokach, S. S. Dritz² , R. D. Goodband, J. M. DeRouchey, J. L. Nelssen, and J. Usry³

 

Summary

A total of 282 nursery pigs (PIC TR4 × 1050, initially 14.5 ± 0.13 lb BW and 3 d postweaning) were used in a 28-d growth trial to determine the effects of replacing high amounts of specialty protein sources with crystalline amino acids (AA) on growth performance of nursery pigs from 15 to 25 lb. Pigs were allotted to 1 of 6 dietary treatments arranged as a 2 × 3 factorial treatment structure. Each treatment had 5 replications with 7 pigs per pen and 2 replications with 6 pigs per pen. Pigs and feeders were weighed on d 0, 7, 14, 21, and 28 to calculate ADG, ADFI, and F/G. A 2-phase diet series was used, with treatment diets fed from d 0 to 14 and a common diet fed from d 14 to 28. All diets were in meal form. Pens were assigned 1 of 3 specialty protein sources with either a low or high crystalline AA level. Thus, diets included either select menhaden fish meal (4.50 vs. 1.00%), porcine meat and bone meal (6.00 vs. 1.20%), or pet food-grade poultry meal (6.00 vs. 1.05%).

 

From d 0 to 14, pigs fed high crystalline AA had improved (P < 0.04) ADG compared with pigs fed the low crystalline AA diets. There was no difference in ADG among pigs fed fish meal, meat and bone meal, or poultry meal. Average daily feed intake and F/G were similar between pigs fed different crystalline AA concentrations or different protein sources. From d 14 to 28, there were no differences in ADG and ADFI between pigs previously fed different crystalline AA levels. There was a tendency for improved (P < 0.04) F/G for pigs previously fed fish meal during Phase 1 compared with pigs fed diets containing meat and bone meal or poultry meal. There was no difference between pigs previously fed different crystalline AA concentrations during Phase 2. Overall (d 0 to 28), dietary crystalline AA had no impact on ADG, ADFI, or F/G. Pigs fed diets containing fish meal from d 0 to 14 tended to have improved ADG for the overall trial compared with pigs fed diets containing meat and bone meal or poultry meal. There were no differences in ADFI or F/G among pigs fed different protein sources. These data suggest that crystalline AA can be used to replace specialty protein sources in nursery pig diets without negatively influencing growth.

 

Key words: crystalline amino acids, nonessential amino acid, nursery pig, protein source

 

Introduction

Several experiments have been conducted to evaluate replacing expensive specialty protein sources with crystalline AA in diets for nursery pigs. Because variable results have been observed among trials, a series of experiments has been conducted at Kansas State University to determine the reason for the inconsistent response. The current trial was the sixth experiment of the series and was conducted to validate the concepts developed in the previous experiments. These concepts included: (1) at least 1.30% standardized ileal digestible (SID) lysine is required for optimal growth, (2) high amounts of crystalline AA can replace select menhaden fish meal with no negative effects on growth performance, (3) supplementation of valine, tryptophan, and nonessential AA is required in low-CP, AA-fortified nursery pig diets, (4) a total lysine:CP ratio no greater than 7.35% should be fed for optimal growth, and (5) at least 65% SID valine:lysine should be fed for maximum growth performance of nursery pigs. In addition to validating the concepts developed from the previous experiments, the objective of this experiment was to determine the effects of replacing high amounts of specialty protein sources with crystalline AA on growth performance of nursery pigs from 15 to 25 lb.

 

Procedures

The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment. The study was conducted at the K-State Swine Teaching and Research Center in Manhattan, KS.

 

A total of 282 nursery pigs (PIC TR4 × 1050, initially 14.5 ± 0.13 lb BW) were used in a 28-d growth trial to evaluate the effects of replacing high amounts of specialty protein sources with crystalline AA on growth performance. Pigs were weaned at approximately 21 d of age and fed a common pelleted starter diet for 3 d. At weaning, pigs were allotted to pens by initial BW to achieve the same average weight for all pens. On d 3 after weaning, pens were allotted randomly to 1 of 6 dietary treatments; thus, d 3 after weaning was d 0 of the experiment. Each treatment had 5 replications with 7 pigs per pen and 2 replications with 6 pigs per pen. All pens (4 × 5 ft) contained a 4-hole, dry self-feeder and a nipple waterer to provide ad libitum access to feed and water.

 

A 2-phase diet series was used, with treatment diets fed from d 0 to 14 and a common diet fed from d 14 to 28. Treatment diets were corn-soybean meal-based and contained 10% dried whey and 1% soy oil. Diets were formulated to a predetermined SID lysine level of 1.30%. Pens were assigned 1 of 3 specialty protein sources with either a low or high crystalline AA level. Thus, diets included either select menhaden fish meal (4.50 vs. 1.00%), porcine meat and bone meal (6.00 vs. 1.20%), or pet food-grade poultry meal (6.00 vs. 1.05%; Table 1). Specialty protein sources were included at low levels in the high crystalline AA diets to ensure a total lysine:CP ratio no greater than 7.36%. Appropriate amounts of crystalline AA were added to treatment diets to maintain SID AA ratios relative to lysine of 52% isoleucine, 58% methionine and cysteine, 62% threonine, 16.4% tryptophan, and 65% valine. The subsequent common diet for all the trials was a corn-soybean meal-based diet with no specialty protein sources, formulated to 1.26% SID lysine. All experimental diets were in meal form and were prepared at the K-State Animal Science Feed Mill. Pigs and feeders were weighed on d 0, 7, 14, 21, and 28 to calculate ADG, ADFI, and F/G.

 

Experimental data were analyzed using analysis of variance as a 2 × 3 factorial with 2 crystalline AA levels and 3 specialty protein sources. Differences between treatments were determined using the PDIFF statement in SAS (SAS Institute, Inc., Cary, NC). Significant differences were declared at P < 0.05 and trends declared at P < 0.10. Pen was the experimental unit for all data analysis.

 

Results and Discussion

From d 0 to 14 (experimental treatment period), pigs fed high crystalline AA had improved (P < 0.04) ADG compared with pigs fed the low crystalline AA diets (Table 2). There was no difference in ADG among pigs fed fish meal, meat and bone meal, or poultry meal. Average daily feed intake and F/G were similar among pigs fed different crystalline AA concentrations or different protein sources during the first period.

 

From d 14 to 28, when the common diet was fed, there were no differences in ADG or ADFI between pigs previously fed different crystalline AA concentrations in place of specialty protein sources. Average daily gain tended (P < 0.09) to decrease for pigs previously fed meat and bone meal and ADFI tended (P < 0.09) to increase for pigs previously fed poultry meal. These tendencies resulted in improved (P < 0.04) F/G for pigs previously fed fish meal during Phase 1 compared with pigs fed diets containing meat and bone meal or poultry meal. There were no differences among pigs fed different crystalline AA levels during the second period.

 

Overall (d 0 to 28), dietary crystalline AA had no impact on ADG, ADFI, or F/G. Pigs fed diets containing fish meal from d 0 to 14 tended to have improved ADG for the overall trial compared with pigs fed diets containing meat and bone meal or poultry meal. There was no difference in ADFI or F/G among pigs fed different protein sources. There were no interactions between dietary treatments during any phases. These data suggest that crystalline AA can be used to replace specialty protein sources in nursery pig diets without negatively influencing growth.

 

 

 

¹ The authors wish to thank Ajinomoto Heartland LLC, Chicago, IL, for providing the synthetic amino acids used in diet formulation and partial financial support.

² Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

³ Ajinomoto Heartland LLC, Chicago, IL.

 

Table 1. Diet composition (as-fed basis)¹

 

******TABLE 1 GOES HERE******

 

¹ A total of 282 nursery pigs (PIC TR4 × 1050) were used in a 28-d trial to evaluate the effects of replacing high amounts of fish meal, meat and bone meal, and poultry meal with crystalline AA on growth performance.

² Treatment diets were fed from d 0 to 14.

³ Common diet was fed from d 14 to 28.

⁴ Phyzyme 600 (Danisco Animal Nutrition, St. Louis, MO) provided 509 FTU/kg, with a release of 0.10% available P.

 

Table 2. Comparison of replacing different specialty protein sources with crystalline amino acids (AA) on growth performance in nursery pigs^1,2

 

******TABLE 2 GOES HERE******

 

¹ A total of 282 nursery pigs (PIC TR4 × 1050) were used in a 28-d growth trial to evaluate the effects of replacing high amounts of specialty protein sources with crystalline AA on growth performance of nursery pigs. Values represent the means of 7 pens per treatment.

² Treatment diets were fed from d 0 to 14 and a common diet fed from d 14 to 28.

³ Pigs were fed either a low or a high crystalline AA level.

⁴ Pigs were fed fish meal, meat and bone meal, or poultry meal.

⁵ There were no dietary interactions between treatments.

 

Evaluation of Heparin Production By-Products in Nursery Pig Diets¹

 

A. J. Myers, M. D. Tokach, R. D. Goodband, M.U. Steidinger² , S. S. Dritz³ , J. M. DeRouchey, J. L. Nelssen, B. W. Ratliff⁴ , and D. M. McKilligan⁴

 

Summary

A total of 1,152 weanling pigs (Newsham GPK35 × PIC380, initially 12.3 ± 1.30 lb, 20 ± 2 d of age) were used in a 39-d study to evaluate the effects of select menhaden fish meal (SMFM), poultry meal, PEP2+, Peptone 50, and PEP-NS on nursery pig performance. PEP2+, Peptone 50, and PEP-NS are all porcine intestinal mucosa products, but they differ in the carriers with which they are co-dried. PEP2+ is co-dried with enzymatically processed vegetable proteins and amino acid (AA) dried fermentation biomass. Peptone 50 is co-dried with a vegetable protein, whereas PEP-NS uses by-products from corn wet-milling as well as dried fermentation biomass.

 

Pigs were randomly allotted to 1 of 6 dietary treatments with 32 pigs per pen and 6 replications per treatment. Treatment diets were fed in 2 phases (d 0 to 7 and d 7 to 21) with a common diet fed to all pigs in the third phase (d 21 to 39). Treatments consisted of a negative control (NC) diet containing 4.5% SDAP in Phase 1 and no specialty protein sources in Phase 2 or the NC diet with 6% poultry meal (PM), PEP2+, Peptone 50, or PEP-NS. From d 0 to 21, pigs fed diets containing 6% SMFM, PM, PEP2+, or PEP-NS had improved (P < 0.05) ADG and ADFI compared with those fed the negative control diet. Pigs fed diets containing 6% SMFM, PM, PEP2+, or PEP-NS had improved (P < 0.05) F/G compared with pigs fed 6% Peptone 50.

 

From d 21 to 39, pigs previously fed diets containing 6% PEP2+ or PEP-NS had improved (P < 0.05) ADG and ADFI compared with those previously fed the negative control diet. Overall (d 0 to 39), pigs fed diets containing 6% SMFM, PM, PEP2+, or PEP-NS had improved (P < 0.05) ADG and ADFI compared with pigs fed the negative control diet. No significant differences were observed among treatments for F/G; therefore, PEP2+ and PEP-NS are suitable replacements for fish meal and poultry meal in nursery diets from d 7 to 21 postweaning.

 

Key words: fish meal, PEP2+, Peptone 50, PEP-NS, spray-dried animal plasma, nursery pig

 

Introduction

Numerous protein sources have been investigated for their efficacy in stimulating both feed intake and growth performance in the weanling pig. Research has indicated that porcine intestinal mucosa, by-products of heparin production, may be suitable replacements for fish meal in nursery pig diets (Jones et al., 2008⁵ ; Myers et al., 2010⁶ ). Porcine digest is derived when mucosa linings from the intestines collected at pork packing plants are removed and hydrolyzed, and the remaining material consists of smallchain peptides. PEP2+, Peptone 50, and PEP-NS (Tech Mix, LLC, Stewart, MN) are by-products of heparin production. Although all of these products originate from intestinal mucosa lining, they vary in that they are co-dried with different carriers to create a final product. PEP2+ is co-dried with enzymatically processed vegetable protein and AA fermentation biomass whereas Peptone 50 is co-dried with an unprocessed vegetable protein. PEP-NS is co-dried with a corn-wet milling by-product and AA dried fermentation biomass.

 

Other specialty protein sources are routinely used in nursery pig diets. Fish meal is a commonly used protein source in nursery pig diets due to its digestibility and desirable AA profile. Furthermore, studies evaluating poultry meal in nursery pig diets have indicated that it can replace fish meal in nursery pig diets without adversely affecting performance. Thus, our objective was to evaluate the effects of Peptone products (PEP2+, Peptone 50, and PEP-NS), select menhaden fish meal, and poultry meal on the growth performance of nursery pigs.

 

Procedures

All practices and procedures used in these experiments were approved by the Kansas State University Institutional Animal Care and Use Committee.

 

A total of 1,152 nursery pigs (Newsham GPK35 × PIC380; initial BW of 12.3 ± 1.30 lb and 20 ± 2 d of age) were used in a 39-d study to evaluate the effects of Peptone products on the growth performance of nursery pigs. The study was conducted at a commercial research wean-to-finish facility in Anchor, IL. The facility was an environmentally controlled, fully slatted, wean-to-finish barn. Pigs were provided ad libitum access to feed and water via a 4-hole dry self-feeder (60 in. long) and 2 cup waterers. Each pen was 220.8 ft² and provided 6.9 ft² /pig floor space. At weaning, pigs were weighed by pen and were randomly allotted to 1 of 6 dietary treatments based upon average pen weight, with 32 pigs per pen and 6 replicate pens per treatment. The number of barrows and gilts were equalized across pens.

 

The 6 dietary treatments were (1) a negative control containing 4.5% SDAP in Phase 1 (d 0 to 7) followed by no specialty protein sources in Phase 2 (d 7 to 21), or (2) the negative control with 6% SMFM, poultry meal, PEP2+, Peptone 50, or PEP-NS. The specialty protein source and crystalline AA replaced soybean meal in the negative control diet. Nutrient profiles, including standardized ileal digestible (SID) values of AA for PEP2+, Peptone 50, and PEP-NS, were provided by the manufacturer (TechMix, LLC, Stewart, MN) and used in diet formulation (Table 1). Spray-dried animal plasma digestibility coefficients obtained from the manufacturer (APC, Ames, IA) and SID AA digestibility values for SMFM and poultry meal used in diet formulation were obtained from NRC (1998).

 

Phase 1 diets were fed in pellet form from d 0 to 7 postweaning (Table 2). Phase 2 diets were fed in meal form from d 7 to 21 (Table 3). A common Phase 3 diet was fed in meal form from d 21 to 39. Average daily gain, ADFI, and F/G were determined by weighing pigs and measuring feed disappearance on d 0, 7, 21, and 39.

 

Data were analyzed as a completely randomized design with pen as the experimental unit. Analysis of variance was performed using the MIXED procedure in SAS (SAS Institute, Inc., Cary, NC). Means were separated using least significant difference (LSD). Results were considered significant at P ≤ 0.05 and considered a trend at P ≤ 0.10.

 

Results and Discussion

From d 0 to 21, pigs fed diets containing 6% SMFM, poultry meal (PM), PEP2+, or PEP-NS had improved (P < 0.05) ADG compared with those fed the negative control diet or diets containing 6% Peptone 50. Pigs fed 6% PEP-NS had increased (P < 0.05) ADG compared with those fed 6% PM. Furthermore, pigs fed 6% SMFM, PM, PEP2+, or PEP-NS had increased (P < 0.05) ADFI compared with those fed the negative control diet. Pigs fed 6% SMFM, PEP2+, and PEP-NS had increased (P < 0.01) ADFI compared with pigs fed diets containing 6% Peptone 50. Pigs fed diets containing 6% SMFM, PM, PEP2+, or PEP-NS had improved (P < 0.05) F/G compared with pigs fed 6% Peptone 50 (Table 4).

 

During Phase 3 (d 21 to 39), pigs previously fed diets containing 6% PEP2+ or PEP-NS had improved (P < 0.05) ADG compared with those previously fed the negative control diet. Pigs previously fed 6% SMFM, PM, PEP2+, or PEP-NS had increased (P < 0.05) feed intake than pigs previously fed the negative control diet or diets containing 6% Peptone 50. Pigs previously fed the negative control diet and diets containing 6% Peptone 50 had improved (P < 0.05) F/G over those fed 6% SMFM or 6% PEP-NS.

 

Overall (d 0 to 39), pigs fed diets containing 6% SMFM, PM, PEP2+, or PEP-NS had improved (P < 0.05) ADG and ADFI compared with pigs fed the negative control diet. Pigs fed diets containing 6% SMFM, PEP2+, or PEP-NS had improved (P < 0.05) ADG and ADFI compared with pigs fed diets containing 6% Peptone 50. No significant differences were observed among treatments for F/G.

 

In conclusion, PEP2+ and PEP-NS are suitable replacements for fish meal and poultry meal in nursery diets from d 7 to 21 postweaning.

 

 

 

¹ Appreciation is expressed to TechMix, LLC, Stewart, MN, and Midwest Ag Enterprises, Marshal, MN, for providing the PEP products and partial financial support.

² Swine Nutrition Service, Anchor, IL.

³ Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

⁴ TechMix, LLC, Stewart, MN.

⁵ Jones et al., Swine Day 2008, Report of Progress 1001, pp. 52-61.

⁶ Myers et al., Swine Day 2010, Report of Progress 1038, pp. 27-34.

 

Table 1. Nutrient composition of ingredients (as-fed basis)

 

******TABLE 1 GOES HERE******

 

¹ Special select menhaden fish meal; Omega Protein Corp., Houston, TX.

² Poultry meal obtained from Hubbard Feeds, Mankato, MN.

³ TechMix, LLC, Stewart, MN.

⁴ Nutrient values from NRC (1998).

⁵ Nutrient values provided by the manufacturer.

⁶ Parentheses indicate standardized ileal digestible amino acid coefficients (%) used in diet formulation.

 

Table 2. Composition of diets, Phase 1 (as-fed basis)¹

 

******TABLE 2 GOES HERE******

 

¹ Phase 1 diets were fed from d 0 to 7 and were in meal form.

² Poultry meal; Hubbard Feeds, Mankato, MN.

³ Special select menhaden fish meal; Omega Protein Corp., Houston, TX.

⁴ PEP2; TechMix, LLC, Stewart, MN.

⁵ Peptone 50; TechMix, LLC, Stewart, MN.

⁶ PEP-NS; TechMix, LLC, Stewart, MN.

⁷ Natuphos (BASF Animal Nutrition; Mount Olive, NJ) provided 509 FTU/kg, with a release of 0.10 available P.

 

Table 3. Composition of diets, Phase 2 (as-fed basis)¹

 

¹ Phase 2 diets were fed from d 11 to 25 and were in meal form.

² Poultry meal; Hubbard Feeds, Mankato, MN.

³ Special select menhaden fish meal; Omega Protein Corp., Houston, TX.

⁴ PEP2+; TechMix, LLC, Stewart, MN.

⁵ Peptone 50; TechMix, LLC, Stewart, MN.

⁶ PEP-NS; TechMix, LLC Stewart, MN.

⁷ Natuphos (BASF Animal Nutrition; Mount Olive, NJ) provided 509 FTU/kg, with a release of 0.10 available P.

 

Table 4. Effects of protein source on nursery pig performance^1,2

 

******TABLE 4 GOES HERE******

 

^a,b,c Within a row, means without a common superscript differ at P < 0.05.

¹ A total of 1,152 nursery pigs (initial BW 12.5 lb) were used in a 39-d trial. Pigs were randomly allotted to 1 of 6 dietary treatments with 32 pigs per pen and 6 pens per treatment.

² Used d 0 body weight as covariate in analysis.

³ 4.5% spray dried animal plasma (APC, Ames, IA) from d 0 to 11 and no specialty protein sources from d 11 to 21.

⁴ Select menhaden fish meal; Hubbard Feeds, Mankato, MN.

⁵ Poultry meal; Hubbard Feeds.

⁶ PEP2; TechMix, LLC, Stewart, MN.

⁷ Peptone 50; TechMix, LLC.

⁸ PEP-NS; TechMix, LLC.

⁹ Common diet was fed from d 21 to 39.

 

 

Evaluating the Effects of Pelleting Deoxynivalenol-Contaminated Dried Distillers Grains with Solubles in the Presence of Sodium Metabisulfite on Analyzed DON Levels¹

 

H. L. Frobose, M. D. Tokach, E. L. Hansen² , L. J. McKinney, J. M. DeRouchey, S. S. Dritz³ , R. D. Goodband, and J. L. Nelssen

 

Summary

Deoxynivalenol (DON), also known as vomitoxin, was prevalent in the 2009 U.S. corn crop and subsequently present in dried distillers grains with solubles (DDGS), in which DON levels are about 3 times higher than the original corn source. One method shown to reduce DON levels was by increasing moisture and temperature when sodium bisulfite was added to DON-contaminated corn (Young et al., 1987⁴ ). Therefore, a pilot study aimed first to replicate these results by placing DON-contaminated DDGS in an autoclave (60 min at 250°F) in the presence of sodium metabisulfite (SMB). The study used 6 treatments: (1) control, (2) 0.5% SMB, (3) 1.0% SMB, (4) 2.5% SMB, (5) 5.0% SMB, and (6) 5.0% SMB with 100 mL/kg water added to evaluate the role of water. After drying, samples were analyzed at North Dakota State University Veterinary Diagnostic Laboratory (NDSU; Fargo, ND). Autoclaving reduced DON levels (R² = 0.99) with increasing SMB, justifying a follow-up study that aimed to assess whether SMB has the same detoxifying effects on corn DDGS in a commercial pellet mill.

 

For this study, batches of 450 lb DDGS were prepared from DDGS with a known DON concentration (23.4 ppm). The pellet mill was set to a production rate of 1,000 lb/h so retention rate and conditioning temperature could be altered within each batch. Within each batch, 4 samples were collected at conditioning temperatures of 150 and 180°F and retention times of 30 and 60 sec within each temperature. Samples were sent to NDSU for full mycotoxin analysis. No differences (P > 0.15) were found in conditioning temperature or retention time on total DON, DON, or acetyl-DON; however, pelleting DDGS reduced (quadratic; P < 0.01) DON and total DON as SMB increased. Based on these results, the reduction in DON and total DON levels appear to plateau somewhere between SMB levels of 2.5 and 5.0%. These results imply that pelleting in combination with SMB may allow pork producers to utilize DON-contaminated DDGS more effectively, but additional research is required to determine the effect of pelleting SMB in DON-contaminated diets on growth performance of pigs.

 

Key words: deoxynivalenol, pelleting, sodium metabisulfite, vomitoxin, nursery pig

 

Introduction

The 2009 corn crop presented challenges for livestock producers due to high concentrations of mycotoxins, particularly DON. Deoxynivalenol, also known as vomitoxin, is one of the most abundant members of the group of mycotoxins known as trichothecenes, which are produced by fungi of the Fusarium genus. Toxin production is strongly dependent on environmental conditions, especially temperature and humidity, so contamination cannot be avoided completely. In growing pigs, concentrations of DON above 1 ppm are associated with reductions in voluntary feed intake, abnormal digestive morphology, and subclinical immune suppression. Nevertheless, swine producers are interested in finding ways to incorporate DON-contaminated feedstuffs into swine diets. When DDGS is produced from DON-contaminated corn, swine producers encounter substantial problems because the DON level in DDGS is 2 to 3 times more concentrated than the original corn source. Due to the particularly high levels and prevalence of DON found in DDGS and other feed grains during so-called Fusarium years such as 2009, the traditional strategy of diluting concentrations during ration formulation may not be a viable option. Furthermore, using adsorbent materials to bind mycotoxins in the digestive tract have proven largely ineffective against mycotoxins in the trichothecene family.

 

Studies by Young et al. (1987⁵ ) and Danicke et al. (2004⁶ ) have both shown significant reductions in DON concentrations when sodium metabisulfite (Na₂S₂O₅) is added prior to hydrothermal treatment of the feedstuff, such as in an autoclave or laboratory conditioner environment. Young et al. (1987) found that pure DON or DON in naturally contaminated feedstuffs reacts readily with sodium bisulfite, the aqueous form of SMB, to form a 10-sulfonate adduct that showed no acute toxic effects when fed to pigs at levels that caused emesis with DON. The initial goal of this study was to attempt to mimic results seen by Young et al. using an autoclave environment and DDGS as the contaminated feedstuff. Following the proof of concept at the autoclave level, we hypothesized that a commercial pellet mill could provide similar hydrothermal conditions through manipulation of retention time and temperature at the conditioner stage of the process. Ultimately, pelleting the original feedstuff or final diet with SMB could be a viable way to decontaminate DON levels and thereby increase the inclusion rate of the DON-contaminated feedstuffs in livestock diets. If SMB is able to detoxify DON effectively, titrating varying concentrations of SMB may reveal the optimal dose for use in livestock diets.

 

Procedures

Autoclave study. All samples used in this pilot study were prepared at the Kansas State University Swine Nutrition Laboratory, with the samples autoclaved at the K-State Food Science Laboratory.

 

The experiment used 6 DDGS treatments: (1) control, (2) 0.5% SMB, (3) 1.0% SMB, (4) 2.5% SMB, (5) 5.0% SMB, and (6) 5.0% SMB with 100 mL/kg distilled water added to evaluate the role of water in the reaction. Each treatment had a final weight of 500 g per sample, except treatment 6 (550g with water). Samples were split into two replicates and placed in aluminum trays with foil covers, but were not sealed airtight to allow steam interaction and gas release. Samples were autoclaved at 250°F for 60 min. After autoclaving, samples were dried in a 131°F drying oven to convert remaining sample to a DM basis before being sent for mycotoxin analysis.

 

All samples were sent for full mycotoxin analysis at NDSU and were analyzed using a combination of mass spectrometry, enzyme-linked immunosorbent assay (ELISA), and high-pressure liquid chromatography (HPLC). Samples were prepared from a previously identified, uniform source of DDGS with a known total DON (DON and 15-Acetyl DON) concentration of 23.9 ppm. The DDGS were homogenized thoroughly prior to sample preparation to eliminate variation in mycotoxin content due to “hot spots” that could cause a discrepancy in initial DON levels. Total DON reflects a combination of DON and 15-Acetyl DON, because both mycotoxins elicit similar effects and are typically combined to form an overall value. Total DON values were adjusted by the proportion of DDGS in the sample to show the actual magnitude of reduction from the original sample.

 

Pelleting study. This study was conducted at the K-State Grain Sciences and Industry Feed Mill. Initially, a 450-lb batch of clean DDGS was pelleted to verify retention times and practice procedures. All personnel involved were required to wear respirators during the pelleting process because sodium metabisulfite gives off toxic sulfur dioxide gas in the presence of heat and moisture.

 

Treatments comprised 450-lb batches of DDGS after the addition of SMB. DDGS were sourced from 3 tons of bagged contaminated DDGS (23.9 ppm DM), which was provided by Hubbard Feeds (Mankato, MN). The experiment used 4 DDGS treatments: (1) control, (2) 1.0% SMB, (3) 2.5% SMB, and (4) 5.0% SMB. Prior to the addition of SMB, each batch was mixed for 4 min in a paddle mixer (Forberg 500 L double-shaft) to homogenize the DDGS and eliminate any variation in initial DON concentration. After adding SMB, each batch was mixed for an additional 3 min before pelleting. The pellet mill (CPM Master Model 1000HD, Crawfordsville, IN) was set to a production rate of 1,000 lb/h so conditioning temperature and retention time could be manipulated within each batch of DDGS. Within each treatment, the pellet conditioner was adjusted so 5-lb samples could be collected at temperatures of 150°F and 180°F and condition times of 30 and 60 sec within each temperature. Pellets were cooled prior to sampling, and the 4 corresponding samples from each batch were ground, homogenized, and sent for mycotoxin analysis at NDSU.

 

Data were analyzed for linear and quadratic effects of SMB and interactions with temperature and retention time using GenStat Release 11.1 (VBN International, 2009). For all statistical tests, significance and tendencies were set at P < 0.05 and P < 0.10, respectively.

 

Results and Discussion

Autoclave study. The results of the DON analysis are shown in Table 1. Mycotoxin analysis verified the expected reduction in DON with increasing SMB (R² = 0.99; Figure 1). Deoxynivalenol concentration was reduced by 13.9% by autoclaving the DDGS (control treatment), and the addition of SMB elicited further detoxifying effects, with 5.0% SMB reducing DON by 76.7%. Adding 10% water to the 5.0% level of SMB also aided in detoxifying DON, reducing it by 88.1%, an 11.4% increase from the 5.0% level alone. Overall, the results of the autoclave experiment confirm the results shown by Young et al. The addition of SMB to DON-contaminated DDGS in an autoclave environment can effectively reduce analyzed DON levels, and the volume of water appears to affect the extent of the detoxification. Although autoclaving DDGS with SMB can substantially decrease DON levels, whether similar results will be seen in commercially viable conditions, such as by adding SMB to DDGS prior to pelleting, remains uncertain. Additionally, whether reductions in analyzed DON levels translate to improvements in animal performance remains unclear.

 

Pelleting study. Results from DON analysis are shown in Table 2. During the pelleting process, the addition of SMB caused a considerable amount of gas to be produced from the pellet mill, and the gas generated a very strong odor and irritation to both the eyes and respiratory tract. Whenever utilizing SMB at levels used in this study in combination with hydrothermal treatment, wearing a full respirator within direct vicinity of the pellet mill is critical.

 

Conditioning temperature had no effect on total DON, DON, or acetyl-DON levels. Additionally, total DON, DON, and acetyl-DON levels were similar across both 30- and 60-sec retention times in the pellet conditioner, so these data are not presented.

 

Pelleting DDGS reduced (quadratic, P < 0.001) DON and total DON levels as SMB inclusion rate increased. According to these results, the reduction in DON and total DON levels appears to plateau somewhere between 2.5% and 5.0% SMB. These results imply that pelleting in combination with SMB may allow swine producers to utilize DON-contaminated DDGS more effectively. Additionally, DON concentrations appear to be reduced in the presence of SMB without requiring adjustment of retention time or conditioning temperature at the pellet mill, simplifying procedures for operators; however, additional research is required to determine if pelleting with SMB can reduce vomitoxin levels in final diets rather than only in individual ingredients such as DDGS. Also, further investigation needs to be conducted into the effects of pelleting with SMB in DON-contaminated diets on the growth performance of pigs.

 

 

 

 

¹ Appreciation is expressed to Hubbard Feeds (Mankato, MN) for supplying the DDGS used in this study.

² Hubbard Feeds, Mankato, MN.

³ Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

⁴ Young, J. C., H. L. Trenholm, D. W. Friend, and D. B. Prelusky. 1987. Detoxification of deoxynivalenol with sodium bisulfite and evaluation of the effects when pure mycotoxin or contaminated corn was treated and given to pigs. J. Agric. Food Chem. 35:259-261.

⁵ Young, J. C., H. L. Trenholm, D. W. Friend, and D. B. Prelusky. 1987. Detoxification of deoxynivalenol with sodium bisulfite and evaluation of the effects when pure mycotoxin or contaminated corn was treated and given to pigs. J. Agric. Food Chem. 35:259-261.

⁶ Danicke, S., H. Valenta, M. Gareis, H. W. Lucht, and H. von Reichenbach. 2005. On the effects of a hydrothermal treatment of deoxynivalenol (DON)-contaminated wheat in the presence of sodium metabisulfite (Na2S2O5) on DON reduction and on piglet performance. Anim. Feed Sci. Tech. 118:93- 108.

 

Table 1. Effects of sodium metabisulfite (SMB) and autoclave on deoxynivalenol (DON) levels in dried distillers grains with solubles (DDGS; DM basis)¹

 

******TABLE 1 GOES HERE******

 

¹ DDGS samples were autoclaved for 60 min at 250°F. After autoclaving, samples were dried in a 131°F drying oven. Mycotoxin analysis took place at the North Dakota State University Veterinary Diagnostic Laboratory (Fargo, ND) and included mass spectrometry, ELISA (enzyme-linked immunosorbent assay), and HPLC (high-pressure liquid chromatography) methods.

² Sodium metabisulfite (Samirian Chemicals, Campbell, CA); 100% by weight.

³ Total adjusted DON = (DON + 15-acetyl DON)/% DDGS in sample (needed to correct for the dilution effect of the addition of SMB). Both DON compounds have similar toxicity, and are typically combined to form an overall DON value.

⁴ Original DDGS sample (90.1% DM). DON levels are converted to a DM basis.

 

Table 2. Effect of pelleting temperature (Temp) and dose of sodium metabisulfite (SMB) on deoxynivalenol (DON) and acetyl-DON in diets containing corn dried distillers grains with solubles (DDGS) naturally contaminated with DON¹

 

******TABLE 2 GOES HERE******

 

¹ No significant effect (P > 0.40) for retention time in pellet conditioner, thus data are not shown.

² No significant temp × SMB interactions (P > 0.69).

³ Standard error of the difference for the temp × SMB interaction. For SED for effect of Temp and SMB, multiply by 0.50 and 0.71, respectively.

⁴ Linear and quadratic effects of SMB.

⁵ Samples analyzed at North Dakota State University Veterinary Diagnostic Laboratory (Fargo, ND) using a variety of mass spectrometry, ELISA (enzyme-linked immunosorbent assay), and HPLC (high-pressure liquid chromatography).

 

******FIGURE 1 GOES HERE******

 

Figure 1. Deoxynivalenol (DON) content of contaminated dried distillers grains with solubles following treatment with sodium metabisulfite (SMB) in an autoclave environment.

 

 

 

Evaluating the Effects of Pelleting, Corn Dried Distillers Grains with Solubles Source, and Supplementing Sodium Metabisulfite in Nursery Pig Diets Contaminated with Deoxynivalenol¹

 

H. L. Frobose, M. D. Tokach, E. L. Hansen² , J. M. DeRouchey, S. S. Dritz³ , R. D. Goodband, and J. L. Nelssen

 

Summary

A total of 360 barrows (PIC 1050, initially 24.7 lb ± 0.3 lb BW and 35 d of age) were used in a 28-d trial examining the effects of pelleting, pelleting dried distillers grains with solubles (DDGS), and supplementing sodium metabisulfite⁴ (SMB) in diets containing deoxynivalenol (DON) on nursery pig performance. Pigs were allotted to 1 of 10 treatments with 7 replications per treatment (pens) and 5 pigs per pen. Naturally contaminated DDGS were used to incorporate DON at desired concentrations. Ingredients were tested for mycotoxins by the North Dakota State University Veterinary Diagnostic Laboratory (NDSU; Fargo, ND) and served as the basis for diet formulation. The 5 experimental diets were fed in meal and pellet form: (1) positive control, (2) negative control (NC, 5.3 ppm DON), (3) NC with 0.5% SMB, (4) pelleted and reground DDGS (5.3 ppm DON), and (5) pelleted and reground DDGS with 2.5% SMB (final diet contained 0.5% SMB). Experimental diets were fed from d 0 to 21 with a common diet fed from d 21 to 28 to evaluate performance after DON was removed. Due to the variability of DON assays when levels exceed 8 ppm, final diets were lower in DON than predicted from analysis of the DDGS. As a result, expected reductions in performance due to DON were not as significant as anticipated, and may have affected results. From d 0 to 21, pigs fed diets with high-DON levels had decreased (P < 0.03) ADG, but the reduction in ADG was only 4%. Pelleting high-DON diets decreased (P < 0.04) ADFI and improved (P < 0.02) F/G compared with diets fed in meal form; however, pelleting DDGS prior to manufacturing final diets had no effect on growth performance. Supplementing SMB tended (P < 0.08) to decrease ADFI, and had no effect on ADG or F/G.

 

Our results indicate that pelleting high-DON nursery pig diets can recover some reduction in feed intake by improving F/G. Although pelleting DDGS and supplementing SMB did not improve performance in DON-contaminated diets, further studies are needed to verify these results.

 

Key words: deoxynivalenol, pelleting, sodium metabisulfite, vomitoxin, nursery pig

 

Introduction

Mycotoxins produced by the Fusarium species present significant challenges globally because weather conditions at the time of cereal flowering ultimately control toxin production. Of the Fusarium toxins, deoxynivalenol (DON, also known as vomitoxin) is of particular importance, because it can be found in toxicologically relevant concentrations that negatively affect farm animal species. Among the most sensitive species are pigs, with concentrations above 1 ppm eliciting a decrease in feed intake and higher levels causing subclinical immune suppression, feed refusal, and vomiting. During so-called Fusarium years, such as 2009, when DON levels cause significant problems, swine producers struggled to find ways to incorporate DON-contaminated feedstuffs into swine diets. Dried distillers grains with solubles produced from DON-contaminated corn also presents considerable problems because mycotoxins become 2 to 3 times more concentrated in the DDGS than in the original corn source.

 

The use of adsorbent feed additives to bind mycotoxins in the digestive tract has shown promise for some mycotoxins, but their efficacy against DON has until now proven ineffective. Other detoxification approaches involve using chemical and/or physical treatments of contaminated feedstuffs before feeding. Young et al. (1987)⁵ demonstrated that in an autoclave, aqueous sodium bisulfite converted DON to a 10-sulfonate adduct (DON-S), which reduced the toxicity of DON-contaminated corn when fed to pigs and subsequent feed intake matched the level of the control group. A recent study (see “Evaluating the Effects of Pelleting Deoxynivalenol-Contaminated Dried Distillers Grains with Solubles in the Presence of Sodium Metabisulfite on Analyzed DON Levels,” p. 90) at Kansas State University attempted to mimic these processing conditions in both an autoclave environment as well as in a commercial pellet mill. Deoxynivalenol levels in contaminated DDGS were significantly reduced after pelleting in the presence of sodium metabisulfite (SMB).

 

Although pelleting with SMB appears to detoxify contaminated DDGS, whether these methods are able to detoxify DON levels in final diets after incorporation of additional ingredients is uncertain. Furthermore, the effects of pelleting DON-contaminated diets in the presence SMB on nursery pig performance are unknown. The goal of this study was to ascertain the influence of both SMB and pelleting DDGS or complete diets containing DON on nursery pig performance. Additionally, this study aimed to determine whether an interaction exists between pelleting and sodium metabisulfite in both DDGS and final diets that are contaminated with DON.

 

Procedures

The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment. The study was conducted at the K-State Segregated Early Weaning Research Facility in Manhattan, KS.

 

A total of 360 barrows (PIC 1050, initially 24.7 lb ± 0.3 lb BW and 35 d of age) were used in a 28-d growth trial. Pigs were allotted to pens by initial weight, and pens were assigned to 1 of 10 treatments in a 2 × 2 × 2 + 2 randomized complete block design, with location in the barn serving as the blocking factor. Each treatment comprised 7 replications (pens) with 5 pigs per pen, and each pen (4 ft by 4 ft) contained a 4-hole dry self-feeder and 1-cup waterer to provide ad libitum access to feed and water.

 

To naturally incorporate DON at desired concentrations, both a clean and a contaminated source of DDGS were supplied by Hubbard Feeds (Mankato, MN) to incorporate DDGS into the test diets at equivalent levels. Base corn and the two sources of DDGS were tested for mycotoxin content at NDSU (Table 1) prior to diet manufacturing. These results were used in diet formulation. Diets were manufactured at the K-State Grain Science Feed Mill. Due to the release of sulfur dioxide gas during pelleting of SMB, all personnel were required to wear respirators and safety goggles to prevent eye or lung damage from the gas. For diets requiring DDGS to be pelleted (7 through 10), the DDGS were pelleted prior to diet manufacturing and re-ground through a hammer mill to ensure no particle segregation at the feeder. Diets requiring the addition of SMB were homogenized for 4 min in a paddle mixer prior to and 3 min after SMB addition to eliminate any discrepancies in initial DON level. For both DDGS and final diets, the pellet conditioner was adjusted to a conditioning temperature of 180°F and a retention time of 30 sec. Pellets were cooled prior to sampling, then reground if in pellet form, and 10 subsamples were collected and compiled to make a composite sample that was shipped to NDSU for a full mycotoxin analysis.

 

Initially, all pigs were fed a commercial SEW diet with a budget of 2 lb/pig followed by a commercial transition diet for the first 7 d postweaning. From d 7 to 14 postweaning, Phase 2 diets were fed. Starting on d 14 (d 0 of the experiment), the 10 experimental treatments (Table 2) were fed to the pigs. Apart from DON and SMB content, diets were formulated to be identical in nutrient composition, and all diets contained a total of 20% DDGS. Based on the initial mycotoxin analysis of base ingredients, 5 experimental diets were fed in meal and pellet form. These included: (1) positive control (PC), (2) negative control (NC, 5.3 ppm DON), (3) NC with 0.5% SMB, (4) pelleted DDGS (5.3 ppm DON), and (5) pelleted DDGS with 2.5% SMB (final diet contained 0.5% SMB). Experimental diets were fed from d 0 to 21. A common diet (<0.5 ppm DON) was fed in meal form from d 21 to 28 to evaluate the change in performance immediately after removing DON from the diet. Average daily gain, ADFI, and F/G were determined by weighing pigs and measuring feed disappearance on d 3, 7, 14, 21, and 28 of the trial.

 

Results were analyzed as a randomized complete block design with a 3-way factorial treatment structure by using the PROC MIXED procedure of SAS (SAS Institute, Inc., Cary, NC) with pen as the experimental unit. Treatment means were separated using the LSMEANS statement and CONTRAST statements in SAS. Two-way interactions between final diet form and DON level were evaluated in positive and negative control treatments. Two- and three-way interactions within high-DON treatments compared final diet form, pelleting DDGS prior to final diets, and SMB inclusion. Means were considered significant at P < 0.05 and trends at P < 0.10.

 

Results and Discussion

The DON analyses of the basal ingredients and test diets are shown in Table 2. Deoxynivalenol values for contaminated DDGS sample varied from 26.5 ppm, the basis of diet formulation, to analyzed levels of 9.7 and 17.9 ppm when analysis was performed again after diet manufacturing. The variation in DON assay results is because the test is designed to analyze samples accurately at 8 ppm or below. When DON levels exceed 8 ppm, samples must be diluted and re-analyzed at laboratory level to quantify actual levels; therefore, at levels exceeding 8 ppm, the variability of results can be significantly greater, as seen in the 3 samples of contaminated DDGS sent for analysis (Table 1). Because of variability in initial mycotoxin analyses, incorporating a high enough level of DON during formulation to generate a true DON response is critical in future studies evaluating strategies to improve growth performance in high-DON containing diets.

 

When contaminated DDGS were pelleted with SMB individually or only in the final diet, analyzed DON levels were reduced from initial concentrations, which supports observations of detoxification by Young et al. (1987), and the conversion of DON to a DON-S form undetected by standard DON assays. However, test diets without SMB formulated to be 5.3 ppm were analyzed at levels between 3.0 and 3.3 ppm, raising concerns about the extent of expected performance reduction in pigs fed NC diets. Diets 7 and 8, where DDGS was pelleted without SMB prior to final diet manufacturing, also had slightly lower analyzed DON levels, indicating that pelleting alone may somewhat detoxify DON, but not to the extent of pelleting with SMB.

 

The growth performance of nursery pigs fed the 10 dietary treatments is shown in Table 3. Statistical analysis also revealed no 2-way interactions between DON level and pelleting in PC and NC diets. No 2- or 3-way interactions occurred within high-DON diets, so they are not reported in Table 3. The PC and NC diets were compared to assess the direct effect of DON and pelleting. High-DON levels decreased (P < 0.01) ADFI and tended (P < 0.06) to decrease ADG between d 0 and 21; however, the DON effect was not as large as expected at only 4% reduction, likely due to the lower than formulated DON levels in NC diets. The common diet period (d 21 to 28) did not affect ADG or ADFI in pigs previously fed high-DON diets, although pigs fed PC diets had better (P < 0.03) F/G in this subsequent period. In previous studies, pigs previously fed high-DON diets experienced compensatory performance during the common diet period with higher ADFI and ADG than pigs fed PC diets. The lack of compensatory growth is another indication that DON levels in NC diets did not produce reductions in performance expected in pigs fed high DON levels. Overall (d 0 to 28), pigs fed NC diets had lower (P < 0.03) ADG, but ADFI and F/G did not differ. Feeding high-DON diets reduced (P < 0.04) pig BW at d 21 and BW remained lower (P < 0.02) at d 28 than pigs fed PC diets.

 

From d 0 to 21, comparing final diet form, pelleting PC, and NC diets decreased (P < 0.01) ADFI and improved (P < 0.02) F/G with no difference in ADG. Pigs previously fed pelleted diets tended (P < 0.07) to have decreased ADFI when switched to meal diets during the common diet period, but the switch had no effect on ADG or F/G. Overall, pelleting PC and NC diets decreased (P < 0.01) ADFI and improved (P < 0.02) F/G compared with meal diets. No differences occurred in pig BW at d 21 or 28 due to pelleting.

 

Within treatments formulated to contain high levels of DON (diets 3 to 10), the effects of pelleting, pelleting DDGS, and SMB were examined. Pigs fed pelleted diets tended (P < 0.06) to have lower ADFI and had improved (P < 0.01) F/G than pigs fed meal diets from d 0 to 21, but there was no difference in ADG. When all pigs were switched to a common meal diet from d 21 to 28, pigs previously fed pelleted diets had increased (P < 0.03) ADG compared with those fed meal diets throughout the trial, but ADFI and F/G were similar. Overall, pigs fed pelleted diets had decreased (P < 0.04) ADFI but improved (P < 0.02) F/G. No differences were measured in pig BW at d 21 or 28.

 

When evaluating DDGS processing prior to final diet manufacturing, pelleting highDON DDGS had no effect on ADG, ADFI, F/G, or pig weights in any period. Supplementing SMB to high-DON diets tended (P < 0.08) to decrease daily feed intake during the experimental period (d 0 to 21), but ADG and F/G were similar. From d 21 to 28, pigs previously fed SMB had decreased (P < 0.04) ADG and tended (P < 0.10) to have decreased ADFI, with no difference in F/G. Overall, supplementing 0.5 % SMB to nursery pigs had no effect on ADG, ADFI, F/G, or pig BW.

 

In summary, obtaining correct DON analysis and providing an adequate level in formulation is crucial to obtain a great enough DON response to adequately test amelioration strategies. In this study, DON levels in negative control diets were approximately 3 ppm, and expected reductions in growth performance were not as great as anticipated; however, pelleting high-DON nursery pig diets can overcome some of the reduction in feed intake by improving F/G. Furthermore, pelleting DDGS prior to diet manufacturing had no effect on performance. Although analyzed DON levels were reduced by supplementing 0.5% SMB, SMB tended to decrease feed intake, which may indicate that the conversion to DON-S is not truly a non-toxic form of DON, or could also indicate palatability issues when including SMB in nursery pig diets. Additional research should be carried out with a greater negative DON response to reinforce these results.

 

¹ Appreciation is expressed to Hubbard Feeds (Mankato, MN) for supplying the DDGS used in this study.

² Hubbard Feeds, Mankato, MN.

³ Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University.

⁴ Sodium metabisulfite, (Na2S2O5), Samirian Chemicals, Campbell, CA; 100% by weight.

⁵ Young, J. C., H. L. Trenholm, D. W. Friend, and D. B. Prelusky. 1987. Detoxification of deoxynivalenol with sodium bisulfite and evaluation of the effects when pure mycotoxin or contaminated corn was treated and given to pigs. J. Agric. Food Chem. 35:259-261.

 

Table 1. Analyzed deoxynivalenol (DON) concentration in diet samples (as-fed basis)^1,2

 

******TABLE 1 GOES HERE******

 

¹ Reported total DON levels as a combination of DON and 15-acetyl DON levels.

² North Dakota State University Veterinary Diagnostic Laboratory, Fargo, ND. Samples were analyzed using a variety of mass spectrometry, ELISA (enzyme-linked immunosorbent assay), and HPLC (high-pressure liquid chromatography).

³ (-) indicates sample was not analyzed at this time.

⁴ After analyzed at 9.7 ppm, the contaminated DDGS sample was reanalyzed due to the major difference from initial value.

 

Table 2. Diet composition (as-fed basis)¹

 

******TABLE 2 GOES HERE******

 

¹ Diets were fed in meal and pellet form.

² Dried distillers grains with solubles.

³ Common diet was fed from d 21 to 28.

⁴ Natuphos 600 (BASF Corporation, Florham Park, NJ).

⁵ Sodium metabisulfite, Samirian Chemicals, Campbell, CA; 100% by weight.

⁶ Formulated deoxynivalenol (DON) level from control and contaminated DDGS was analyzed at North Dakota State University Veterinary Diagnostic Laboratory prior to diet manufacturing with DON levels of 0.7 and 26.5 ppm, respectively.

 

Table 3. Effect of pelleting, dried distillers grains with solubles (DDGS) source, and sodium metabisulfite (SMB) on growth performance of nursery pigs fed deoxynivalenol (DON)-contaminated diets¹

 

******TABLE 3 GOES HERE******

 

¹ A total of 360 barrows (initial BW of 24.7 lb ± 0.3 lb BW and 35 d of age), with 5 pigs per pen and 7 replicates per treatment.

² Formulated deoxynivalenol (DON) levels of <0.5 and 5.3 ppm total DON. Analyzed DON levels are shown in Table 2.

³ All interactions were excluded from the table due to lack of significance.

⁴ NC, negative control; PC, positive control.

⁵ Treatments contained a final level of 0.5% SMB added during final diet manufacturing.

⁶ Treatments had 2.5% SMB added prior to pelleting DDGS; final SMB level of 0.5%.

⁷ A common diet was fed from d 21 to 28.