Effects of Conjugated Linoleic Acid on Performance, Egg Quality, Yolk Firmness and Yolk Fatty Acid Composition of Primiparous Laying Hens
WANG Shenghui1,2, SHI Zhaoguo1, WANG Jing2, ZHANG Haijun2, QI Guanghai2, WU Shugeng2, ZHANG Tao3
1. College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China;
2. Key Laboratory of Feed Biotechnology of Ministry of Agriculture, National Engineering Research Center of Biological Feed, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China;
3. Evonik Degussa Co., Ltd., Beijing 100026, China
Abstract：This experiment was conducted to study the effects of dietary conjugated linoleic acid (CLA) on performance, egg quality, yolk firmness and yolk fatty acid composition of primiparous laying hens. Six hundred and thirty 18-week-old Hy-Line brown laying hens with similar body weight and laying rate were randomly divided into 7 groups with 6 replicates per group and 15 hens per replicate by single factor randomized test design. Laying hens were fed the experimental diets contained 0, 1%, 2%, 3%, 4%, 5% and 6% CLA, respectively. The adaptation period lasted for 1 week and the formal period lasted for 8 weeks. The results showed as follows:1)the performance and egg quality of laying hens in 1% and 2% CLA groups were no significant differences(P>0.05). Compared with control group, eggshell thickness in 2%, 3% and 4% CLA groups was increased(P>0.05), laying rate in 3%, 4%, 5% and 6% CLA groups was significantly decreased and yolk firmness was significantly increased (P<0.05), average daily feed intake and abdominal fat rate in 4%, 5% and 6% groups were significantly decreased(P<0.05), the ratio of feed to egg in 5% and 6% CLA groups was significantly increased and yolk percentage was significantly decreased (P<0.05). 2) The contents of C16:0, C18:0 and saturated fatty acid (SFA) in yolk in 1% and 2% CLA groups were significantly lower than those in the other groups (P<0.05). Compared with control group,the contents of C16:0, C18:0 and SFA in yolk in 4%, 5% and 6% groups were significantly increased (P<0.05), and the contents of C16:1, C18:1, monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) were significantly decreased (P<0.05). The content of CLA in yolk was quadratically significantly increased with the increase of CLA supplemental level (P<0.01). The enrichment of c9,t11-CLA in yolk was 1.47 times of t10,c12-CLA. It is concluded that diet supplemented with 2% CLA can improve the quality of eggshell, decrease the content of SFA in yolk and a certain amount of CLA can be enriched in yolk, and has no effects on performance and egg quality of laying hens.
