Early dietary amino acid (AA) restriction is suggested to produce compensatory and leaner growth with more efficient utilization of nutrients. Similarly, 5% dietary lipids could reduce novo lipogenesis and increase leanness. A total of 64 pigs (Yorkshire) were used to investigate the effect of early dietary amino acid (AA) restrictions and flaxseed oil supplementation on grower-finisher pigs. A factorial arrangement (2 x 2) was used for AA restriction (100 or 80% of the 2012 NRC SID Lys requirements during the grower and finisher-1 phases) and flaxseed oil supplement (0 or 3%, +2% poultry fat). At 24.7 ± 0.5 kg of BW, pigs were randomly assigned to 4 grower diets with 4 gilt pens and 4 castrated male pens per treatment and 2 gilts or 2 castrated males/pen. Switch to fnisher-1 diets was applied at 51.2 ± 0.3 kg of BW and to finisher-2 diets at 80.0 ± 0.4 kg. Those receiving 0 or 5% lipids during the grower and finisher-1 phases continued at those levels. Ultrasound backfat measurements and blood samples were collected at the end of the grower, finisher-1 and finisher-2 phases. Finally, pigs were harvested at 110.5 ± 0.5 kg to assess carcass traits and physical and sensory characteristics of pork.
During the grower phase, although AA restricted pigs consumed less feed, SID Lys, and digestible energy, their average daily BW gain was not depressed. During the finisher-1 phase, however, pigs fed the AA restricted diets had greater BW gain and utilized SID Lys more efficiently than those fed the unrestricted diets. Pigs supplemented with lipids had lower feed intake but greater BW gain during the grower phase, and their BW gain:feed was improved during all phases of production. Overall BW gain was not affected by the early dietary AA restrictions, but overall efficiency of feed, SID Lys, or DE utilization for BW gain was improved by the AA restrictions. The early dietary AA restrictions had no effect on fat-free lean (FFL) gain but increased FFL gain:SID Lys and tended to increase FFL gain:DE. Serum urea-N at the end of the grower and finisher-1 phases was reduced, whereas serum glucose was increased at the end of the grower phase by AA dietary restriction. The dietary lipids tended to increase and increased serum triglycerides at the end of the grower and finisher phases (1 and 2), respectively. Besides, lipids reduced urea-N for the finisher-2 phase. The dietary lipids increased serum cholesterol in pigs fed the unrestricted diet but had no effect on those fed with AA restriction, at the end of the finisher-1 phase. Generally, the AA restrictions reduced flavor intensity and tended to reduce meat tenderness. Dietary lipids reduced belly firmness and tended to increased off-flavor. Dietary treatments did not affect backfat depth.
In conclusion, the dietary lipids strategy improved gain:feed but reduced belly firmness and slightly increased off-flavor. The dietary AA restrictions had no effect on overall BW gain or FFL gain although improved overall efficiency of AA and DE utilization for BW and FFL gain.
Adhikari, C. K., Chiba, L. I., Brotzge, S. D., Vieira, M. S., Huang, C., W.G. Bergen, C.L. Bratcher, S.P. Rodning, and E.G. Welles (2017). Early dietary amino acid restrictions and flaxseed oil supplementation on the leanness of pigs and quality of pork: Growth performance, serum metabolites, carcass characteristics, and physical and sensory characteristics of pork. Livestock Science, 198, 182-190. https://doi.org/10.1016/j.livsci.2017.02.003