THE EFFECT OF DIETARY HERRING MEAL ON THE OMEGA-3-FATTY-ACID CONTENT OF PLASMA AND EGG-YOLK LIPIDS OF LAYING HENS

The effect of dietary HM on plasma and egg yolk lipids of commercial W hite Leghorn hens was studied over 350 d. A total of 192 birds were gi ven 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 (1 69, 211, 253 and 287 d) and at five times during the test day (0800, 1 000, 1200, 1400 and 1600 h) were performed. Egg lipids were analyzed a t 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 (20:5n 3,EPA) and docosahexaenoic (22:6n3,DHA) acid were 11 and 3 times highe r, respectively (7.8 and 100.5 mg yolk(-1)) in the yolks from hens giv en the 12% HM diet compared to the control diet.