Effect of Time and Fatty Acid Composition in Eggs of White Leghorn Hens Supplemented with Tuna Oil

The study evaluated the effect of time and fatty acid (FA) composition in eggs of laying hens supplemented with tuna oil (TO). Two hundred White Leghorn hens 30-week were divided into 5 treatments with 4 replicates of 10 birds each. Treatments were assigned randomly and consisted of 0%, 0.75%, 1.50%, 2.25% and 3% TO in commercial sorghumsoybean meal diets, in which the soybean oil was partially replaced. The experiment was conducted for 90 days. At days 28, 56 and 84 of the experiment, 10 eggs per replicate were collected for chemical analysis. Feed intake, egg production rate, egg weight, and feed conversion were not influenced by dietary treatment. FA content was significantly altered (P < 0.05) by TO, showing a progressive increase in egg n-3 FA (especially docosahexaenoic [DHA] and eicosapentaenoic [EPA] acids) when TO was added. Levels of EPA and DHA were higher (P < 0.05) in the egg lipids of TO fed hens than those in the control group. This was correlated (P < 0.05) with the concentration of TO in the diet. However, no significant differences were observed either in egg weight or percent of egg lay between groups. There was a high correlation (P < 0.05) between TO inclusion level in the diet and the incorporation of EPA (r = 0.96) or DHA (r = 0.92) into the egg yolk and an overall decrease in n-6 FA. There was a high correlation (P < 0.05) between TO inclusion level and the incorporation of linoleic acid (LA, r = −0.95) or arachidonic acid (AA, r = −0.96) into the egg yolk. The highest incorporation (P < 0.05) of total n-3 FA content in eggs was obtained with 3% TO/kg. This increase was proportional to TO inclusion levels in the diets (r = 0.95). The results indicate that the n-3 FA content in eggs can be increased by dietary supplementation with TO, and that TO can serve as a reasonable alternative feed ingredient in layer diets to produce a healthier choice of egg.