The effect of dietary HM on plasma and egg yolk lipids of commercial White Leghorn hens was studied over 350 d. A total of 192 birds were given corn-wheat-soybean meal diets that contained either 0, 4, 8, or 12% HM. Analysis of plasma lipids at four periods in the laying cycle (169, 211, 253 and 287 d) and at five times during the test day (0800, 1000, 1200, 1400 and 1600 h) were performed. Egg lipids were analyzed at each of the four periods.Plasma total lipids were inversely related (P < 0.01) to dietary HM levels while omega-3 and omega-6 fatty acid levels were positively and inversely related (P < 0.001), respectively. HM levels did not influence the total lipid content of the egg yolk lipids but omega-3 and omega-6 fatty acid content were positively and inversely related, respectively. The levels of eicosapentaenoic (20:5n3, EPA) and docosahexaenoic (22:6n3, DHA) acid were 11 and 3 times higher, respectively (7.8 and 100.5 mg yolk−1) in the yolks from hens given the 12% HM diet compared to the control diet. Key words: Herring meal, laying hens, omega-3 fatty acids, eicosapentaenoic acid, docosahexaenoic acid
Determination of the Fatty Acid Composition of Milk Fat by Dual Column Temperature Programmed Gas-Liquid Chromatography
