L-茶氨酸对黄羽肉鸡生产性能和免疫功能的影响

本试验旨在探讨L-茶氨酸对黄羽肉鸡生产性能和免疫功能的影响。选用1日龄黄羽肉鸡690只,随机分为6个处理,每个处理5个重复,每个重复23只。6个处理分别为对照组(饲喂无抗生素基础饲粮)、抗生素组饲喂在基础饲粮中添加10%硫酸黏杆菌素的饲粮,前期(1～3周)添加200 mg/kg,后期(4～7周)添加150 mg/kg]、4个不同梯度(100、200、400和800mg/kg)L-茶氨酸试验组,试验期为49 d。试验检测了黄羽肉鸡的生产性能、免疫器官指数、肠道分泌性免疫球蛋白A(sIgA)含量及血清溶菌酶活性、抗体水平和免疫细胞因子含量等指标。结果表明:在试验前期,100 mg/kg L-茶氨酸组黄羽肉鸡的体增重显著低于其他各组(P<0.05),100、200和800 mg/kg L-茶氨酸组黄羽肉鸡的法氏囊指数显著低于对照组(P<0.05),各L-茶氨酸组黄羽肉鸡的肠道sIgA含量和血清干扰素-γ(IFN-γ)含量显著高于对照组(P<0.05)。在试验后期,与对照组及抗生素组比较,L-茶氨酸对黄羽肉鸡生产性能、免疫器官指数、肠道sIgA的含量影响不显著(P>0.05);100、200和400 mg/kg L-茶氨酸组黄羽肉鸡血清白细胞介素-2(IL-2)的含量显著高于对照组(P<0.05),200和400 mg/kg L-茶氨酸组黄羽肉鸡血清IFN-γ的含量显著高于对照组(P<0.05)。在整个试验期,各组黄羽肉鸡血清溶菌酶的活性和白细胞介素-4的含量差异不显著(P>0.05);一免后第6天,100和200 mg/kg L-茶氨酸组黄羽肉鸡血清新城疫抗体滴度显著低于对照组和抗生素组(P<0.05),一免后第14天,100、200和400 mg/kg L-茶氨酸组黄羽肉鸡抗牛血清白蛋白(BSA)抗体水平显著高于对照组(P<0.05),其他各阶段各组间的抗BSA抗体水平和新城疫抗体滴度均差异不显著(P>0.05)。由此可知,饲粮添加L-茶氨酸对黄羽肉鸡生长后期生产性能、免疫器官指数均无显著影响,说明其对黄羽肉鸡后期生长是安全的;同时L-茶氨酸可提高黄羽肉鸡生长前期肠道sIgA的含量、后期血清IL-2的含量及全期血清IFN-γ的含量,从而增强其机体免疫功能。

Effects of L-Theanine on Performance and Immune Function of Yellow-Feathered Broilers

The purpose of this study was to investigate the effects of L-theanine on the performance and immune function of yellow-feathered broilers.A total of 690 one-day-old yellow-feathered broilers were randomly divided into 6 groups with 5 replicates per group and 23 birds per replicate.The groups were divided into a control group(non-antibiotic group),an antibiotic group(added 10% of colistin sulphate,200 mg/kg during 1 to 3 weeks,150 mg/kg during 4 to 7 weeks),4 different levels of L-theanine(100,200,400 and 800 mg/kg) groups.The trial lasted for 49 days.Performance,immune organ indices,intestinal secretory immunoglobulin A(sIgA),serum lysozyme activity,antibody level and immunocytokine contents were investigated.The results showed as follows: 1) during the period of 1 to 3 weeks,the body weight gain of 100 mg/kg L-theanine group was significantly lower than that of the other groups(P<0.05),the bursa of fabricius index of 100,200 and 800 mg/kg L-theanine groups was significantly lower than that of the control group(P<0.05).The contents of intestinal sIgA and serum interferon-γ(IFN-γ) in L-theanine groups were significantly higher than those of the control group(P<0.05).2) During the period of 4 to 7 weeks,there were no significant differences in the performance,immune organ indices and intestinal sIgA content among L-theanine groups,control group and antibiotic group.Serum interleukin-2(IL-2) content of 100,200 and 400 mg/kg L-theanine groups was significantly higher than that of the control group(P<0.05),and serum IFN-γ content of 200 and 400 mg/kg L-theanine groups was significantly higher than that of the control group(P<0.05).3) During the entire experimental period,there were no significant differences in serum lysozyme activity and interleukin-4(IL-4) content among all groups(P>0.05).Lower anti-Newcastle disease virus(NDV) titers of 100 and 200 mg/kg L-theanine groups were found on day 6 post primary immunization compared with the control group and antibiotic group(P<0.05),but higher anti-bovine serum albumin(BSA) antibody levels of 100,200 and 800 mg/kg L-theanine groups were found on day 14 post primary immunization compared with the control group(P<0.05),and there were no differences in anti-NDV titers and anti-BSA antibody level among all groups during the other periods(P>0.05).In conclusion,there were no significant differences in performance and immune organs indices during the later trial period of broilers supplemented L-theanine,which indicate that L-theanine is safe for broilers.And the L-theanine supplementation can bring about higher intestinal sIgA content of early experimental period,serum IL-2 content of later experimental period and serum IFN-γ content of entire experimental period,so the immune function of broilers are enhanced by the diets supplemented L-theanine.