Optimal Paylean Sequence (Step-up/Step-down) When Fed to Late-finishing Swine

Purdue University 2002 Swine Research Report. Previous research trials that were conducted at Purdue University with Paylean have shown that even though growth performance parameters of pigs fed Paylean stay at levels above conventionally fed pigs, performance parameters peak and slowly decline 4 to 6 weeks after animals are fed this product. Average daily gain (ADG) peaks, then plateaus until approximately day 21, followed by a decline, and lean accretion is affected in a similar way. Fat deposition rate in pigs fed Paylean declines immediately and remains lower the first 10-14 days on Paylean. During subsequent time on Paylean, fat deposition rates are lower but parallel control pigs. The effects explained above are enhanced as the level of Paylean is increased. Although the effects seen in fat deposition are desired, questions have been raised as to why growth performance and protein accretion parameters plateau and then decline. Possible explanations may include: 1) Receptors to this product begin to be desensitized when feeding a constant level of Paylean and 2) As the animals growth potential begins to decline, so does the responsiveness to the product. With the recent approval of Paylean to be fed to pigs from 150-240 lb of body weight (BW), multiple feeding regimes are being examined to identify which will maximize growth performance and carcass characteristics while minimizing cost to the producer. Most pigs receiving Paylean are fed a constant level between 4.5-18 g/ton of feed. This trial was designed to determine whether the response to Paylean could be enhanced or maintained if fed at increasing and/or decreasing intervals during the finishing phase compared to pigs that were fed a constant level throughout the finishing stage. Specific objectives of this trial were to determine whether the response could be extended if Paylean dose were increased throughout the finishing phase, and whether the response to Paylean would be maintained if Paylean dose were decreased throughout the finishing trial. Therefore, a late-finishing study (last six weeks) was conducted to evaluate the effects of feeding a constant level of Paylean vs. a phase-feeding treatment of varying Paylean levels on ADG, average daily feed intake (ADFI), feed efficiency (F:G), fat and loin depth, carcass weight, premiums, percent yield, percent lean, and lean cut weights. This trial was conducted over a sixweek period from June to July, 2000.