N-3Polyunsaturated Fatty Acid Of Different Sources Enrichment In Eggs And Its Effects On Laying Performance And Egg Quality

It is possible to modify the fatty acid profile of the yolk by changing the lipidsources of the hen diet. However, several researchers have reported impaired layingperformance and egg quality in hens fed n-3PUFA sources. An experiment was carriedout to evaluate the effect of dietary fat sources on egg n-3PUFA deposition profile, and on hen'slaying performance and egg quality.One hundred eighty healthy laying hens (25 wk of age) were allotted to 5 dietarytreatments, with each treatment replicated 6 times with 6 birds for replicate. Diet 1 wasthe control treatment, supplying with the corn-soybean basal diet. Diet 2 contained 10％linseed and 1％fish oil. Diet 3 contained 10％linseed and 5％dehulled double-lowrapeseed. Diet 4 contained 5％linseed and 10％double-low rapeseed. Diet 5 contained5％linseed and 10％dehulled double-low rapeseed. The details were as follows:1. Effect of dietary n-3PUFA sources on n-3PUFA content of egg yolk. Theconcentrations of ALA in yolks from hens fed 10％linseed +1％fish oil and 10％linseed+5％dehulled double-low rapeseed groups were higher than other groups (P＜0.01), thecontent of ALA from hens fed 10％linseed +5％dehulled double-low rapeseed groupwas 14 times of the content from the control. 5％linseed +10％double-low rapeseed and5％linseed +10％dehulled double-low rapeseed groups showed lower values of ALAthan 10％linseed +1％fish oil and 10％linseed +5％dehulled double-low rapeseedgroups. Regression analysis indicated that dietary ALA content played important roles inALA content in eggs. There was significant linear relationship between them (R~2=0.95,P＜0.01).Dietary n-3PFUA significantly increased the proportions of EPA and DHA in eggyolk (P＜0.01). The content of EPA and DHA in the 10％linseed +1％fish oil group were0.18％, 1.96％, respectively. The composition of EPA and DHA in other groups werelower than 10％linseed +1％fish oil group (P＜0.01), but just failed to reach statisticalsignificance between them. Regression analysis indicated that dietary ALA, EPA andDHA content had effect on egg EPA content (R~2=0.89, P＜0.01). However, onlysignificantly linear negative relationships between dietary ALA and egg DHA werefound(R~2=0.83, P＜0.01).n-3PUFA content of yolks from hens fed 10％linseed and 1％fish oil wassignificantly higher (P＜0.01) than in yolks from hens fed the control or otherexperimental diets. The decreasing order of n-3PUFA content was: 10％linseed and 1％fish oil＞10％linseed and 5％dehulled double-low rapeseed＞5％linseed and 10％ undehulled double-low rapeseed＞5％linseed and 10％dehulled double-low rapeseed.Regression analysis indicated that there was significant linear relationship betweendietary ALA, EPA and egg n-3PUFA (R~2=0.94, P＜0.01).AA content in yolk from 10％linseed and 1％fish oil was much lower than theother groups (P＜0.01). Regression analysis indicated that there was significant negtiverelationship between dietary ALA, EPA, DHA and egg AA (R~2=0.97, P＜0.01).2. Effect of dietary n-3PUFA sources on Hen's laying performance and serum lipid.Feed intake in 5％linseed +10％dehulled double-low rapeseed group was decreased(P＜0.05). Egg weight did not vary over the experimental groups(P＞0.05). Eggproduction in 5％linseed +10％dehulled double-low rapeseed group significantlydecreased (P＜0.05). There was no significant difference in F/E.Dietary n-3PUFA significantly decreased serum TC (P＜0.05) and TG (P＜0.05)concentration. 10％linseed +5％dehulled double-low rapeseed group had the lowestserum TC and TG values, which decreased 56％and 64％than the control, respectively.3. Effect of dietary n-3PUFA sources on egg quality.Egg quality was not influenced by the dietary n-3PUFA sources (P＞0.05). Eggorganoleptic evaluation decreased with the diet added n-3PUFA sources, organolepticevaluation in 10％linseed + 1％fish oil group was -1～0.25, showing a significantreduction in overall acceptability.TMA content were higher in the groups supplied n-3PUFA sources (P＜0.05),especially in 10％linseed and 1％fish oil group, 2.85 times of the content of the control.The composition of TMA in 10％dehulled double-low rapeseed group was higher thanthe content in 10％double-low rapeseed group(P＜0.05).The content of MDA in the groups added n-3PUFA sources were also higher thanthe control. 1％fish oil group increased mostly (P＜0.05). The content of MDA in 10％linseed +5％dehulled double-low rapeseed and 5％linseed +10％dehulled double-lowrapeseed groups increased 31.8％, 30.8％than the control.These data suggested that: Comparing with linseed and rapeseed, fish oil had thebetter value in content of n-3PUFA especially the content of DHA. However, fish oilmight increase the TMA and MDA content, decreasing egg overall acceptability, whichnot good for the production of eggs rich in n-3PUFA. It was concluded that the dietcontaining 10％linseed and 5％dehulled double-low rapeseed seemed to be accepted toproduce eggs rich in n-3PUFA...