Effects of Dietary Fats on Triacylglycerol Composition and Structure of Egg Yolk Lipids

Abstract

Effects of dietary soybean oil, coconut oil, lard and beef tallow on the changes in triacylglycerol (TG) composition and structure in egg yolk lipids of laying hens were studied. Generally, the fatty acid composition of egg yolk TG reflected partially that of the dietary fats fed to hens, though, the short chain saturated fatty acids (C8:0, C10:0) were not availably utilized for the egg yolk lipid formation. Egg yolk TG from hens fed soybean oil, lard and beef tallow was commonly composed of C50, C52 and C54 species as main TG components. More TG species of C44-C50 were contained in egg yolk of coconut oil group than in that of the other diet groups, while, C52 and C54 components were less in coconut oil group. Egg yolk lipid of soybean oil group contained less amounts of TG comprising monoenoic acids and more of TG comprising dienoic acid than the other groups. Lipid of coconut oil group contained the most amount of S2M and the least of U3 among the experimented diet groups. Lipids from lard and tallow group comparatively resembled each other in distribution pattern of TG species. In egg yolk TG from every dietary group, saturated fatty acids were preferentially esterified at position 1 of TG, on the contrary, position 2 comprised predominantly unsaturated fatty acids. Position 3 was largely occupied by C18:1 accompanied with C16:1. This species specificity of positional distribution of fatty acids in hen's egg TG was not changed regardless of variation of dietary fats fed to hens.