N-乙酰半胱氨酸对热应激条件下肉仔鸡生长性能、肠道能量和抗氧化状态及空肠形态的影响

摘要

试验旨在研究日粮添加N-乙酰半胱氨酸对热应激条件下肉仔鸡生长性能、肠道能量和抗氧化状态及空肠形态、消化酶水平的影响.选取健康、体重一致的1?d雌性AA商品代肉仔鸡720只,随机分为4组,每组6个重复,每个重复30羽.试验日粮采用2(常温和热应激)×2(基础日粮和基础日粮+0.1％N-乙酰半胱氨酸),试验共进行35?d.结果显示:热应激显著降低了肉鸡平均日采食量和平均日增重(P＜0.05);与基础日粮组相比,日粮添加N-乙酰半胱氨酸显著体高了肉鸡平均日采食量和平均日增重(P＜0.05);日粮和热应激对肉鸡料重比存在显著的交互作用(P＜0.05).热应激显著降低了肉鸡空肠粘膜ATP和AEC的含量(P＜0.05),显著提高了空肠粘膜AMP的含量(P＜0.05);日粮和温度对空肠AMP含量的影响存在显著的交互效应(P＜0.05).热应激显著提高了肉鸡血清皮质醇的含量(P＜0.05),同时显著降低了血清T3、T4的水平(P＜0.05).热应激显著降低了绒毛高度与隐窝深度比值,显著提高了隐窝深度(P＜0.05).日粮添加N-乙酰半胱氨酸较基础日粮组显著提高了绒毛高度与隐窝深度比值(P＜0.05).热应激显著降低了肉鸡空肠AKP、脂肪酶和胰蛋白酶含量(P＜0.05),但日粮添加N-乙酰半胱氨酸显著提高胰蛋白酶的含量(P＜0.05).热应激显著降低B淋巴细胞的mRNA相对表达水平(P＜0.05),显著提高细胞凋亡蛋白酶3?mRNA相对表达水平(P＜0.05).日粮添加N-乙酰半胱氨酸显著提高了B淋巴细胞mRNA相对表达水平(P＜0.05).结果提示:日粮添加0.1％N-乙酰半胱氨酸可以提高热应激条件下肉鸡的生长性能,改善肠绒毛形态,提高消化酶含量,维持肠道能量和抗氧化状态.%The present study was conducted to investigate the effect of supplementation of supplementation of N-acetylcysteine(NAC)on growth performance,intestinal energy and antioxidation status,and intestinal morphology of broilers under heat-stressed.A total of 720 AA commercial broilers were randomly allotted to 4 groups with 6 replicates of 30 broilers.The diets were designed as 2(thermoneutral or heat stress)×2(basal diet and basal diet+0.1％N-acetylcysteine)factors,the trial last 35 d.Results showed that broilers exposed to the heat stress had lower(P＜0.05)feed intake and weight gain than broilers under thermoneutral condition.NAC supplementation increased the feed intake(P＜0.05)and weight gain.Heat stress decreased(P＜0.05)the concentrations of adenosine triphosphate(ATP)and adenylate energy charge(AEC),while increased(P ＜ 0.05)the level of adenosine monophosphate(AMP)in the jejunal mucosa of broilers compared with the thermoneutral group.Serum concentration of corticosterone was elevated(P ＜ 0.05),while levels of T3 and T4 were decreased(P＜0.05)in broilers under heat stress than broilers under thermoneutral condition,and broilers fed with NAC diet exhibited lowe(r P＜0.05)concentration of corticosterone than broilers fed with the basal diet.Heat stress induced a reductio(n P＜ 0.05)in the ratio of villus height to crypt depth.Heat stress group showed lower(P ＜ 0.05)activities of activities of alkaline phosphatase(AKP),lipase and trypsine in the jejunum.Heat stress induced the downregulation B-cell lymphoma expression(P＜0.05)and the upregulation(P＜0.05)of caspase-3 in the jejunal mucosa of broilers.In conclusion,dietary supplementation of 0.1％NAC improved the growth performance,intestinal morphology and absorptive function,maintained intestinal energy metabolism,and mitigated intestinal oxidative stress in the heat-stressed broilers.