Effect of nursery diet complexity and weaning age on pig growth performance and health status
Purdue University 1996 Swine Research Report. The weaning age and weight of pigs in a swine operation dictate the feeding program that is used for the nursery pigs. Traditionally, the younger pigs are weaned, the more complex and costly is the feeding program. Pigs weaned earlier can be healthier, if separated from the sows and older pigs. They will carry less disease into the nursery from the sow herd, because they still have natural immunity from the colostral antibodies and disease exposure from the sow is no longer present, allowing the pigs to clear the pathogens from their systems. As more pigs are weaned in an early weaning system (< 17 days of age), it is being observed that these healthier pigs can utilize a less complex diet and still maintain good growth rates. Our objective was to compare two diet complexity nursery feeding sequences, fed to either segregated early weaned or conventionally weaned pigs. Materials and Methods
Two experiments were conducted to evaluate diet sequence complexity and segregated early weaning (SEW) versus conventional weaning (CON). In Experiment 1, 288 (Cotswold terminal cross) littermate barrows (12/pen) from a commercial producer were used. Two barrows per litter were weaned at 13 (SEW) and two were weaned at 20 (CON) d of age (4 barrows/litter total) to separate off-site and on-site nurseries, respectively. SEW barrows were fed a 4-diet sequence and CON barrows were fed a 3-diet sequence. Two diet complexities (COMP vs SIMP) were fed to both weaning ages, creating a 2 x 2 factorial treatment arrangement (weaning age and site x diet complexity). All SEW barrows were fed a complex early-wean commercial diet during the initial week after weaning, from d 13 to 20 of age. Diet complexity treatments were then imposed on both of the different weaning ages at a common age of 20 d. The two experimental diet complexities were fed in three phases, from d 20 to 27 (Phase 1), d 27 to 41 (Phase 2), and d 41 to 55 (Phase 3) of age. Pigs were allotted and blocked by initial weight and ancestry. Blood samples were taken at weaning and at the end of the nursery period from one pig per pen to determine tumor necrosis factoralpha (TNF) activity from blood monocytes as an indicator of health status. Pigs and feeders were weighed weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency.
Experiment 2 used 168 (York x Landrace x PIC 405) barrows and gilts (7/pen) from the Purdue Animal Science Research Center, with a similar experimental design and dietary treatments (2 x 2 factorial). Pigs in this experiment averaged 13.5 d of age for the SEW and 23 d of age for the CON environments. Littermates were not used in Experiment 2; instead intact litters were either SEW or CON weaned.
Dietary complexity was adjusted by varying the levels of plasma protein, lactose, soybean meal, blood meal, and fish meal (Table 1) to create the two diet complexity feeding sequences. Dietary lysine levels were maintained at 1.50, 1.35, and 1.25% for each diet sequence at each phase of production, for Phase 1, 2, and 3, respectively. The remainder of the diets were corn based and all diets were pelleted.
Results and Discussion
Experiment 1. Health status between weaning ages was similar based on cultured organisms and blood indicators, with both environments supporting low disease prevalence. Pigs fed the COMP diet sequence had numerically better feed efficiency for the CON weaned pigs during Phase 1, Phase 3 and overall (Table 2). However, the SIMP diet supported greater (P < .05) ADG and ADFI during Phase 3 and overall (20 to 55 d of age) for both weaning ages. Pigs weaned at SEW age were 2.4 lb lighter at 20 d of age compared to CON weaned pigs (11.7 vs. 14.1 lb). However, SEW pigs were 3.1 lb heavier at 55 d of age (48.3 vs. 45.2 lb). Pigs weaned at SEW age gained 5.5 lb more weight in 35 d than CON weaned pigs, indicating that more than reduced disease loads are stimulating pig growth when pigs are SEW weaned compared to CON weaned.
Experiment 2. Pigs that were SEW weaned had greater ADG and ADFI (P < .05; Table 2) during the first week of the experiment (Phase 1). However, pigs that were conventionally weaned had greater ADG (P < .05) during Phases 2 and 3. Conventionally weaned pigs had greater ADFI (P < .05) during Phase 3 and overall than the SEW pigs. Feed efficiency was better (P < .05) during Phase 2 for the CON weaned pigs, but was poorer during Phase 3 and overall. The CON pigs had a 1 lb heavier weight at the beginning of the trial (12.5 vs. 11.5 lb) but weighed less after the Phase 1 period than the SEW pigs (15.05 vs. 16.1 lb). However, due to the higher feed intake during Phase 3 (.4 lb ADFI) and overall, the CON pigs were 2.7 lb heavier at the end of the experiment. The likely reason for the large difference in feed intake during Phase 3 between environments is the feeder designs. Pigs in the SEW environment were fed in troughs 3 times daily and the pigs fed in the CON environment were fed from a typical ad libitum stainless steel nursery feeder, likely allowing for slightly more feed intake when the pigs got heavier. Diet complexity only influenced the Phase 1 period of the experiment, with the more complex diet having greater feed intake (P < .05) but poorer feed efficiency (P < .05).
The TNF concentrations were not different at weaning time for the SEW or CON pigs (93.4 vs 106.4 pg/mg monocyte DNA). However, at the end of the experiment, pigs that were SEW had lower levels (P < .05) of TNF than pigs in the CON environment (41.1 vs 168.6 pg/mg DNA). This would indicate that the SEW pigs had less disease exposure and actually cleared the pathogens they had contracted from the sow herd from their system. The CON pigs’ TNF levels increased, indicating that they were still being exposed to the diseases of the swine operation.
This research indicates that growth performance of high health pigs can be equal or better when fed less complex dietary sequences, at least after the initial post-weaning diet phase. The complex dietary treatment has its greatest benefit during the first week post-weaning, when early consumption without digestive problems is critical. Once the pig is eating well, this research would indicate that the pig could be switched to a less complex diet more aggressively during the remainder of the nursery period. The opportunity therefore exists to control or reduce nursery feed costs. Early weaning of pigs does reduce the disease present in the nursery, thereby improving growth rate and feed intake. However, if the herd is relatively free from disease, the improvement from early weaning is greatly reduced and requires greater thought as to the use of this practice when one considers the negative impact early weaning has on the sow herd.
Table 1. Diet description
|Sequence I||Sequence II|
|High Complex||(% of Diet)||Low Complex||Lysine %|
|SEW Group Only / 14-21 days of age|
|Both Weaning Groups / 21-28 days of age|
|28-42 days of age|
|42 to 56 days of age|
Table 2. Effect of diet complexity and weaning age on pig growth performance
|Item||COMP||SIMP||COMP||SIMP||SE||P < .05|
|Exp. 1 / ADG, lb.|
|d 0 to 7||0.260||0.258||–||–|
|d 7 to 14||0.515||0.542||0.381||0.324||.096||Weaning Age|
|d 14 to 28||0.921||0.941||0.689||0.769||.06||Diet, Weaning Age|
|d 28 to 42||1.37||1.45||1.30||1.33||.09||Diet, Weaning Age|
|d 7 to 42||1.02||1.07||0.870||0.910||.04||Diet, Weaning Age|
|d 0 to 7||0.300||0.300||–||–|
|d 7 to 14||0.606||0.579||0.258||0.267||.05||Weaning Age|
|d 14 to 28||1.16||1.20||0.740||0.800||.08||Weaning Age|
|d 28 to 42||1.95||2.11||1.96||2.24||.21||Diet|
|d 7 to 42||1.37||1.44||1.13||1.27||.09||Diet, Weaning Age|
|Pig BW, lb.|
|Initial, d 7||11.7||11.7||13.9||14.3||.34||Weaning Age|
|d 14||15.4||15.4||16.5||16.5||.62||Weaning Age|
|d 28||28.2||28.6||26.2||27.3||1.0||Weaning Age|
|d 42||47.4||48.9||44.3||46.0||1.4||Diet, Weaning Age|
|Exp. 2 / ADG, lb.|
|d 0 to 7||0.310||0.302||–||–|
|d 7 to 14||0.654||0.687||0.395||0.352||0.025||Weaning Age|
|d 14 to 28||0.782||0.791||0.864||0.879||0.031||Weaning Age|
|d 28 to 42||1.183||1.244||1.339||1.293||0.042||Weaning Age|
|d 7 to 42||0.883||0.916||0.961||0.939||0.028|
|d 0 to 7||0.357||0.378||–||–|
|d 7 to 14||0.784||0.728||0.474||0.392||0.026||Diet, Weaning Age|
|d 14 to 28||1.075||1.084||1.098||1.064||0.031|
|d 28 to 42||1.507||1.616||1.979||1.953||0.057||Weaning Age|
|d 7 to 42||1.190||1.226||1.325||1.285||0.033||Weaning Age|
|Pig BW, lb.|
|Initial, d 7||11.5||11.5||12.5||12.5||0.29||Weaning Age|
|d 14||16.1||16.3||15.2||14.9||0.29||Weaning Age|
|d 42||42.4||43.6||46.1||45.3||1.0||Weaning Age|