Effect Of Vitamin A And Conjugated Linoleic Acid On Production Performance Of Laying Hens And Fatty Acid Composition Of Yolk

The experiment was conducted to study the effect of adding vitamin A (VA) and conjugated linoleic acid (CLA) in layer dietary on the production performance, egg quality, blood biochemical parameters of laying hens and the cholesterol and fat acid composition of egg yolk. In order to determine whether VA could solve the problem of the content of saturated fatty acid was increased and the content of monounsaturated fatty acid was decreased in developing conjugated linoleic acid-rich egg and provided a theoretical basis for developing healthy and secure functional foods.A3x3double factors cross-group design was adopted in this experiment. The treatments with3VA level:0%、2%and4%and3CLA level:4000IU/kg、8000IU/kg and16000IU/kg. A total of216healthy hy-line brown laying hens were assigned randomly to9groups of24layers each. Each group was assigned3replication and8layers per replications. The trial period was6weeks.The results showed as follow:1. Production performanceDietary CLA significantly decreased the laying rate(.P<0.05). The difference in the feed intake, egg production and feed conversion rate were not significant (P>0.05). The optimal amount of CLA adding in the diet of laying hens was2%.The laying rate of vitamin A in8000IU/kg was very significantly higher than the laying rate of16000IU/kg level (P<0.01), and other performance indicators were best in the vitamin A was8000IU/kg. The interaction of VA and CLA did not significantly influence on the production performance (P>0.05).2Egg qualitiesDietary CLA very significantly decreased the egg weight (P<0.01),and significantly increased the percent of yolk and the yolk color (P<0.05).Dietary VA significantly increased the egg weight(P<0.05). The interaction of VA and CLA did not significantly influence on the egg quality (P>0.05).3Blood biochemical parametersDietary CLA very significantly increased the content of high density lipoprotein and low density lipoprotein (P<0.01), but had on significantly influence on others blood biochemical parameters(P>0.05).Dietary VA significantly increased the content of serum total cholesterol and significantly decreased the content of serum calcium (P<0.05), but had on significantly influence on others blood biochemical parameters(P>0.05). The interaction of VA and CLA did not significantly influence on the blood biochemical parameters (P>0.05).4. Fat acid composition of egg yolkDietary CLA very significantly increased the content of saturated fatty acid and significantly decreased the content of monounsaturated fatty acid in yolk (P<0.01).Dietary VA significantly increased the content of monounsaturated fatty acid in yolk in the CLA level of0%(P<0.05). Dietary VA could ease the negative influence of dietary CLA on the CLA-rich egg to some extent. The interaction of VA and CLA did not significantly influence on the fat acid composition of egg yolk (P>0.05).5. Cholesterol of egg yolkDietary CLA very significantly decreased the cholesterol of egg yolk (P<0.01) and the reduction effects was best in the level of2%.Dietary VA and the interaction of VA and CLA had on significant effect on the cholesterol of egg yolk.