Effects of Animal Fat, Flaxseed Oil, and Vitamin E on Growth Performance and Metabolic Profile of Finisher Pigs, Physical and Organoleptic Characteristics of Pork, and Gene Expression in Adipose and Muscle Tissues of Finisher Pigs

Abstract

Producing high-quality pork is an integral part of successful and sustainable pig production. Lipid content and composition is central to the nutritional value and eating quality of pork. The objective of this project was to investigate the effect of dietary lipids and vitamin E supplementation on growth performance, serum metabolic profile, carcass characteristics, fatty acid (FA) profile, physical and organoleptic characteristics of pork, and expression of genes associated with lipid metabolism. A total of 96 pigs (initial body weight, 54 ± 3.4 kg) were used to investigate the effects of lipids [0, 1, 3, and 5% poultry fat (+ 1% flaxseed oil for diets with supplemental lipids)] and vitamin E (11 or 220 IU vitamin E/kg) in a 4 x 2 factorial arrangement with 3 gilt pens and 3 castrated male pens per treatment and 2 gilts or 2 castrated males per pen. Standardized ileal digestible Lys, Ca, and P were adjusted accordingly with the DE content. All diets were formulated to meet or exceed the 2012 NRC nutrient requirements. Blood samples were collected at the end of finisher 2 phase. Pigs were harvested at approximately 110 kg, and standard carcass data were collected. Loin chops were collected for the determination of physical and sensory characteristics of pork. Adipose and muscle samples were collected for gene expression analysis. There were no lipid x vitamin E interactions on growth performance. Lipid supplementation improved gain:feed (linear, P < 0.01) during finisher 1, finisher 2, and overall phases, increased weight gain (linear; P = 0.028) during finisher-2, and increased (linear, P < 0.05) belly thickness. There were lipid x vitamin E interactions on fat-free lean percentage and backfat thickness at 10th rib (P < 0.05). Vitamin E supplementation increased carcass leanness in pigs fed the 6% dietary lipids, but increased fatness in pigs fed the diets containing 2 and 4% lipids. Vitamin E supplementation increased serum α-tocopherol content (P < 0.001) and NPPC marbling score (P < 0.05). The percentage of the saturated FA and monounsaturated FA were reduced by lipid supplementation (linear, P < 0.05). Serum cholesterol and triglyceride increased (linear, P < 0.01) and the percentage of ω-6 polyunsaturated FA in muscle increased (linear, P < 0.001) with increased dietary lipids. Flaxseed oil supplementation increased ω-3 polyunsaturated FA and decreased the ω-6 to ω-3 ratio (P < 0.001). No clear differences were found on physical characteristics, belly firmness, oxidative stability, and sensory evaluation in pork, and gene expressions associated with lipid metabolism in adipose and muscle tissues. These results indicated that vitamin E supplementation increased NPPC marbling score, and animal fat and flaxseed oil could improve feed efficiency, and flaxseed oil was effective in improving the nutritional value of pork as indicated by ω-6 to ω-3 ratio without negative effect on organoleptic characteristics or oxidative stability of pork.