Early dietary amino acid restrictions and flaxseed oil supplementation on the leanness of pigs and quality of pork: Growth performance, serum metabolites, and carcass traits

Abstract Text: A total of 64 pigs were used to assess the effect of early dietary AA restrictions [100 or 80% of the 2012 NRC standardized ileal digestible (SID) Lys requirements during the grower (G) and finisher (F)-1 phases] and lipids (0 or 3% flaxseed oil + 2% poultry fat) on G-F pig. Each phase was based on weight, and at 24.7 ± 0.5 kg, pigs were assigned to 4 G diets with 4 gilt pens and 4 barrow pens/diet, and switched to F-1 diets when they reached 51.2 ± 0.3 kg. Pigs were switched to common F-2 diets at 80.0 ± 0.4 kg, and pigs fed 0 or 5% lipids earlier were continued to receive 0 or 5% lipids until harvest at 110.5 ± 0.5 kg. There were no interactions between dietary AA restrictions and lipids. Pigs fed the AA restricted diets consumed less SID Lys and DE (P < 0.015) and had depressed ADG compared with unrestricted pigs during the G phase, but they grew faster (P = 0.042) and utilized feed (P = 0.064) and SID Lys (P < 0.001) more efficiently during the F-1 phase. Dietary AA restrictions had no effect on overall ADG or carcass traits. Overall efficiency of feed, SID Lys, and DE utilization for BW gain (P < 0.004) and SID Lys utilization for fat-free lean gain (FFLG; P < 0.001) was improved by dietary AA restrictions. Dietary AA restrictions reduced serum urea N (P < 0.025) at the end of the G and F-1 phases and increased glucose (P = 0.027) at the end of the G-phase, but had no clear effect on triglycerides (TG) and other metabolites. Dietary lipids reduced ADFI (P < 0.064) during the G and F-2 phases, improved G:F (P < 0.047) during all phases and overall, and improved ADG during the G (P = 0.003) and F-1 (P = 0.066) phases. Belly firmness was reduced (P < 0.001), but dietary lipids had no effect on other carcass traits. Dietary lipids increased TG (P < 0.075) at the end of the G and F-1 phases, but reduced urea-N (P= 0.037) at the end of the F-2 phase. In conclusion, pigs subjected to early dietary AA restrictions improved overall efficiency of AA and DE utilization for BW gain and FFLG. As expected, dietary lipids improved G:F but reduced belly firmness.  

Keywords: early amino acid restrictions, flaxseed oil, pigs