Diets high in linoleic acid reduce omega-3 long chain polyunsaturated fatty acids in chicken tissues

Abstract

We have previously demonstrated that the level of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) could be increased several fold by increasing the level of alpha-linolenic acid (ALA) in broiler feed. The lowest LA to ALA ratio of experimental diets resulted in the highest n-3 LCPUFA, EPA, DPA and DHA in both breast and thigh tissues. Because the n-6 PUFA, linoleic acid (LA), competes for the enzymes used to produce n-3 LCPUFA, the effect of dietary LA on n-3 LCPUFA accumulation in chicken meat was unclear. The objective of this study was to examine the effect of varying LA levels in diets on the conversion of ALA into EPA, DPA and DHA into chicken tissues. The level of ALA in the diets was held constant at 2.1% energy (% en) while the level of LA varied from 2.9 to 4.4% en. The ratio of LA to ALA of the experimental diets thus ranged from 1.4:1 to 2.1:1. The results indicated that the total n-3 LCPUFA levels in the breast meat of birds fed with the lowest LA content was 16% higher than the n-3 LCPUFA in the breast of birds fed with the highest LA content. In general, the decrease in n-3 LCPUFA due to inhibition by LA was less than the stimulatory effect of an equivalent level of ALA on n-3 LCPUFA accumulation. This study indicated that the strongest influence on n-3 LCPUFA accumulation in chicken tissues was the level of ALA in the diet. The experimental diets did not appear to affect the growth performance of chickens. We conclude that there was only a modest effect of dietary LA on omega-3 LCPUFA accumulations in chicken meat, but diets that are lower in LA will allow greater conversion of ALA into n-3 LCPUFA.