Effects of dietary n-6/n-3 PUFA ratio on growth performance and lipid metabolism in nursery pigs.

Abstract

The proportion of n-6 and n-3 polyunsaturated fatty acid (PUFA) in commercial pig feed is severely unbalanced. This study was conducted to investigate the effects of different n-6/n-3 PUFA ratios on growth performance and lipid metabolism of nursery pigs. A total of 240 nursery pigs (Duroc &#xd7; Large White &#xd7; Landrace) were fed diets with different n-6/n-3 PUFA ratios, including 10:1, 5:1, 3:1, and 1.5:1. Pigs fed diet with n-6/n-3 PUFA ratio of 1.5:1 or 3:1 had optimum average daily gain and feed to gain ratio (&#x202f;<&#x202f;0.05). The levels of serum lipids including total cholesterol, triglyceride, high density lipoprotein and low density lipoprotein were the lowest in pigs fed diet with n-6/n-3 PUFA ratio of 1.5:1 (&#x202f;<&#x202f;0.05). The concentrations of serum insulin, adiponectin and leptin were the highest in pigs fed diet with n-6/n-3 PUFA ratio of 3:1 (&#x202f;<&#x202f;0.05). Pigs fed diet with n-6/n-3 PUFA ratio of 3:1 had the highest abundance of genes associated with fatty acid absorption and transportation (, and), synthesis and storage (and) and degradation (,, and) in intestine (&#x202f;<&#x202f;0.05). Pigs fed diet with n-6/n-3 PUFA ratio of 1.5:1 had the lowest abundance of genes associated with fatty acid absorption (and), synthesis and storage (,,,,, and) and degradation (and) in gastrocnemius muscle (&#x202f;<&#x202f;0.05). The mRNA expression of genes associated with fatty acid metabolism (,,,,,,,,,,, and) was up-regulated in liver and subcutaneous fat of pigs fed diet with n-6/n-3 PUFA ratios of 1.5:1-5:1 (&#x202f;<&#x202f;0.05). In summary, diets with lower n-6/n-3 PUFA ratios improve growth performance, reduce blood lipids, facilitate lipid metabolism in intestine, liver and subcutaneous fat, and inhibit fatty acid absorption, synthesis and storage in gastrocnemius muscle in pigs.