Effect Of Dietary Conjugated Linoleic Acid On Lipid Metabolism And Immune Performance Of Broilers

Conjugated linoleic acid(CLA) is a polysaturated fatty acids which was found a lot of beneficial biological properties. Chinese and foreign scientists hadn't go deep into research of CLA until Pariaza found a substance in crude and roasted beef which can restrain the activity of inducement and restrain cancer in 1978. Then it was named CLA and not only had the functions of enhancing lipid mechanism, immunity, anticarcinogenic function, antioxidant function and promoting bone growth and so on, but also influence performance of livestocks. Whereas, the paper examined the effect of dietary CLA on performance, lipid metabolism and immune function. This study aimed to serve as the base for further research and application on CLA.In the experiment, total 144 3-week-old health male AA broilers were randomly assigned to six groups with four replicates of six broilers per group. The broilers were fed six dietary treatments containing 0%, 0.25%, 0.50%, 0.75%, 1.0% or 1.25% CLA . Soybean oil and CLA source were substituted on a weight basis in different diets. Experimental period was four weeks.After 2 week and 4 week dietary treatment, birds were slaughted to collected samples to test HI, T3, T4, TP, ALB, BIB, CHOL, TG, HDL, LDL, IgA, IgG, IgM in serum, and removed abdominal fat and immune organ ( Spleen, Thymus, Bursa.F.) to measure their weight.The results of the experiment are that:From 4th week to 7th week, Diet supplemented with 0.75% and 1.0% CLA could significantly improve feed conversion ratio of broilers (P<0.05), 12.16% and 10.36% higher to the constract, respectively. Feed intake of supplementary 0.5% CLA group reduced significantly (P<0.05), 12.95% lower to the contract. Body daily gain of Broilers increased with the increment of CLA,but it isn't significant(P>0.05).Supplementary CLA significantly reduced abdominal fat rate and thickness (P<0.05). It reduced HDL and increased LDL, LDL/HDL, TG, CHOL sightly, but no significant difference (P>0.05).There was significantly increased immune organ index in broilers with supplementary CLA, Especially Thymus index (P<0.01).Thymus index of 1.0% CLA group are higher 50.00%(35d age) and 43.04% (49d age) than the control.IgA, IgG, IgM and HI in serum decrease significantly (P<0.05) at first and then increase (P>0.05) with supplementary CLA.Dietary CLA slightly improved T₃, T₄ and T₄/T₃ in serum and then decrease (P>0.05).Dietary CLA could improved the content of TP, ALB and BIB (P>0.05). Considering all factors, the optimal dosage of CLA is 0.75 % 1.0 % in broilers diets.