Effect Of Dietary Oil Sources On Egg Quality And The Content Of Polyunsaturated Fatty Acids Of Yolk

The composition and contents of fatty acids in egg yolks could be modulted by alteration of fatty acid profile in layer diets. Enrichment of polyunsaturated fatty acids (PUFAs) has been supposed to be beneficial to human health. However, it may put negative effect on egg quality. In this study, four different sowros of dietary fatty acids were applied to investigate the influence of oil sources on fatty acid composition of egg yolk and on egg quality.One hundred and twenty Hylian brown layers of 330-d old were fed a corn- soybean meal based diet to meet or exceed the recommended breed nutrition requirement. Layers were randomly divided into five groups to receive basal diet (CONTR), and control diet added 5% tallow (Treatment 2), 5% soybean oil (Treatment 3), 5% fish oil (Treatment 4) and 5% linseed oil (Treatment 5) , respectively. Experimental diets were formulated to be isoenergetic and isonitrogenous to avoid the energy- and/or protein- derived change in fatty acid profile of egg yolk. Every treatment involved 24 layers and 2 birds were housed in one cage. Layers were allowed to free access to the diets and water. Following one-week acclimated feeding, eggs were collected from each treatment layers at each end of the week for 4-wk to assay the fatty acid composition of egg yolk.There is no effect of dietary supplemented oil on egg quality when compared with egg from control layers. No differences were observed in egg yolk color,egg albumen height and egg shape index among all dietary treatments. There were no differences of egg weight among treatment 1,2,3 and 5. However, the layers fed diet contained tallow (+7.73%), soybean oil (+6.22%), and linseed oil (+7.08%) have heavier egg weight than layers fed fish oil diet. The results show that the dietary added oil has no effect on egg yolk color,egg albumen height and egg shape index, when Fish oil seemed to reduce the egg weight during the overall period of study(P < 0.05)..The result show the content of n-6 polyunsaturated fatty acids (n-6 PUFA) in egg yolk is related to the content of oil in dietary. The significant n-6 PUFA content differences are exist among all dietary.. Soybean oil (+54.64%) and linseed oil (26.79%) significantly increased the content of n-6 polyunsaturated fatty acids (n-6 PUFA), the contet of n-6 PUFA in egg yolk of soybean oil treatment are highst among those treatment and come to 10.31%. The variation trend of the n-6 PUFA contet is the same as that of the content of Linoleic acid (LA) in dietary.The differences of n-3 PUFA are not detected (P>0.05) between the treatment control diet added 5% tallow (Treatment 2), whereas the differences of n-3 PUFA are significant among other treatments. The content of n-3 PUFA of treatment 5,4,3,2 are higher as 776.1%, 443.28%,138.81% and 14.93% at the 28th day of experiment than that of control group, respectively.This study indicated that the ratio of n-6/n-3 should be considered. The ratio of n-6/n-3 10.17:1 at the 28th day of experiment. And that of treatment 5,4,3,2 are 1.5:1, 1.61:1, 6.47:1 and 7.64:1 respectively (P < 0.01). It is feasible to modulate the ratio of n-6/n-3 PUFA of egg yolk by adjusting the proportion of n-6/n-3 of diets to produce the designed egg to meet the human requirementConcoluntly, the chicken use the dietary fat acid to form yolk fat directly, and the composition of yolk fat acid are similar to that in dietary. We can change the content of yolk fat acid and produce the healthy egg food through varing the content of dietary fat acid.