Dietary Fish Oil for Hens Affects the Fatty Acid Composition of Egg Yolk Phospholipids and Gives a Valuable Food with an Ideal Balance of n-6 and n-3 Essential Fatty Acids for Human Nutrition.

Abstract

A fish oil diet affected the metabolism of essential fatty acids in both serum and egg yolk, and lowered the serum cholesterol level. The blood samples and eggs were obtained from hens fed diets containing either fish oil (21 g/kg diet) or a blend of vegetable oils for 2 months after 6-month-feeding with regular commercial diets. The concentrations of n-3 polyunsaturated fatty acids, eicosapentaenoic acid (20:5 n-3, EPA), docosapentaenoic acid (22:5 n-3, DPA) and docosahexaenoic acid (22:6 n-3, DHA), increased significantly in the sera and eggs from hens fed the fish oil diet (p<0.001, respectively). On the other hand, a significant reduction in arachidonic acid (20:4 n-6, AA) was found in the sera and eggs compared to those of controls (p<0.001, respectively). The ratios of AA (20:4 n-6)/DHA (22:6 n-3) were 0.21 in the sera and 0.12 in the egg yolks compared with those of 1.88 and 1.77 in controls, respectively. The variation in fatty acid composition in egg yolks was found in the acyl groups of phospholipids, phosphatidylcholine and phosphatidylethanolamine, rather than in those of triacylglycerol. The findings show that supplementing the diet for hen with fish oil alters essential fatty acid composition, in particular by increasing DHA and decreasing AA in egg yolk phospholipids. In conclusion, hens fed a diet containing fish oil (2.1%), a relatively lower level of fish oil content than the control, gives lower priced commercial eggs which are an ideal food with a recommended n-6/n-3 essential fatty acid balance for human health and nutrition.