急性热应激对肉仔鸡生长性能及脂肪代谢的影响

Effects of Acute Heat Stress on Growth Performance and Lipid Metabolism of Broilers

本试验旨在探讨急性热应激对肉仔鸡生长性能及脂肪代谢的影响。试验选用了体重相近的健康的28日龄爱拔益加(AA)雄性肉仔鸡120只,随机分成3组:急性热应激组、对照组和饲粮配对组,每组4个重复,每个重复10只鸡。试验期为7 d。结果表明:与对照组比较,急性热应激组AA肉仔鸡的平均日采食量和平均日增重分别显著下降33.84%、65.01%(P<0.05),料重比增加89.14%(P<0.05)。同时,与饲粮配对组相比,急性热应激组的平均日增重降低28.29%(P>0.05),料重比增加42.27%(P>0.05)。急性热应激显著增加了肝脏、腹脂和颈皮下脂肪的相对重量(P<0.05),同时有增加腿皮下脂肪相对重量的趋势(P>0.05)。急性热应激对血清中游离脂肪酸和总胆固醇含量均无显著影响(P>0.05),但显著增加了甘油三酯、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇的含量(P<0.05),对照组与饲粮配对组相比以上血清生化指标均无显著差异(P>0.05)。急性热应激显著增加了肝脏乙酰辅酶A羧化酶和脂肪酸合成酶及腹脂脂肪酸合成酶基因的mRNA相对表达水平(P<0.05),同时显著降低了肝脏脂蛋白脂酶基因的mRNA相对表达水平(P<0.05)。由此可知,急性热应激可使AA肉仔鸡生长性能下降,营养成分重分配,脂肪沉积增加。

The experiment was conducted to study the effects of heat stress on growth performance and lipid metabolism of broilers.One hundred and twenty 28-day-old healthy male AA broilers with similar body weight were randomly allotted to three treatments（4 replicates per treatment with 10 birds per replicate）： constant heat stress at 34 ℃ with ad libitum feeding（acute heat stress group）,constant optimal ambient temperature at 21 ℃ with ab libitum feeding（control group）,and constant optimal ambient temperature at 21 ℃ but pair-fed with the amount consumed by the acute heat stress group（pair-fed group）.The experiment period was 7 d.The results showed as follows： compared with the control group,average daily feed intake（ADFI） in acute heat stress group was decreased by 33.84%（P0.05）,average daily gain（ADG） was decreased by 65.01%（P0.05）,and the ratio of feed to gain（F/G） was decreased by 89.14%（P0.05）.Compared with pair-fed group,ADG in acute heat stress group was decreased by 28.29%（P0.05）,and F/G was increased by 42.27%（P0.05）.The fat deposition of acute heat stressed AA broilers were increased in hepatic fat（P0.05）,abdominal fat（P0.05）,cervical subcutaneous fat（P0.05）,and thigh subcutaneous fat（P0.05）.The contents of free fatty acid（FFA） and total cholesterol（TC） in serum of acute heat stressed AA broilers had no significant change（P0.05）,but the contents of triglyceride（TG）,high density lipoprotein-cholesterol（HDL-C） and low density lipoprotein-cholesterol（LDL-C） were significantly increased（P0.05）,but there was no significant difference in serum biochemical indices between control group and pair-fed group（P0.05）.Acute heat stress significantly increased acetylcoa carboxylase（ACC） and fatty acid synthase（FAS） in liver and FAS in abdominal fat（P0.05）,and significantly decreased lipoprotein lipase（LPL） gene mRNA expression（P0.05）.These results indicate that acute heat stress decreases growth performance of AA broilers,redistributes nutrient constituents,and increases fat deposition.