Production of n-3PUFA Enriched Eggs By Feeding Various Dietary Ratios of n-6 to n-3 Fatty Acids and Vitamin A Levels to the Laying Hens in Hot Climate

In the present study, the effect of various dietary ratios of linoleic acid (LNA) to alpha-linolenic acid (ALA), and vitamin A (Retinyl Acetate) on egg quality and some blood metabolites was examined in laying hens kept at high ambient environmental temperature. Three hundred and sixty laying hens were fed rations supplemented with different combinations of canola oil and linseed oil to have LNA to ALA dietary ratios of 20:1, 10:1, 4:1, 2:1, 1:1 and 1:2, each with 3000IU or 10000 IU vitamin A/kg of diet (6 X 2 factorial; under Completely Randomized Design). Various blood metabolites, egg cholesterol, egg triglycerides and egg-yolk fatty acids were determined during the last week of the study. The results showed that serum triglycerides, serum total- and low density lipoprotein-cholesterol, and blood glucose were similar (P > 0.05) in laying hens; fed on various dietary LNA/ALA ratios and vitamin A levels. Consequently, egg cholesterol and egg triglycerides were also similar (P > 0.05) for the all dietary treatments. However, Serum high density lipoprotein-cholesterol increased (P=0.045) with the decrease in dietary LNA/ALA ratio. The n-3 polyunsaturated fatty acids (PUPA) in egg yolks from laying hens were increased (P < 0.001) while, the n-6 PUFA and the ratio of n-6 to n-3 fatty acids were decreased (P < 0.001) with the decrease in dietary LNA/ALA ratio. It was recommended that a dietary ratio of 4:1 or less between LNA and ALA was quite beneficial for the production of eggs by the hens with desirable quantities of n-6 and n-3 PUFA that are suitable for human consumption.