饲粮中添加共轭亚油酸和铬对热应激肉鸡生长性能、胴体性能、肉品质及脂肪沉积的影响

Effects of Conjugated Linoleic Acid and Chromium on Growth Performance,Carcass Performance,Meat Quality and Fat Deposition of Heat-Stressed Broilers

本试验旨在研究饲粮中添加共轭亚油酸(CLA)和铬(丙酸铬)对热应激肉鸡生长性能、胴体性能、肉品质及脂肪沉积的影响。试验采用2×3两因素随机试验设计,设置2个CLA水平(0、1%)和3个铬水平(0、0.2、0.4 mg/kg)。选用216只1日龄科宝(Cobb)500白羽雌雏肉鸡,随机分为6个组,每组6个重复,每个重复6只鸡。环境温度保持在32~34℃,每周末进行1次肉鸡体温(肛温)的测定,以确保其处于热应激状态。试验期42 d。结果表明:1)饲粮中添加CLA和铬以及二者互作对热应激肉鸡平均日采食量、平均日增重和料重比均无显著影响(P>0.05)。2)饲粮中添加CLA提高了热应激肉鸡腿肌率(P<0.05),并有提高屠宰率的趋势(P=0.071),但对胸肌率、全净膛率均无显著影响(P>0.05)。饲粮中添加铬有降低热应激肉鸡胸肌率的趋势(P=0.099)。CLA和铬互作对热应激肉鸡胴体性能没有显著影响(P>0.05)。3)饲粮中添加CLA降低了热应激肉鸡胸肌和腿肌黄度(b^(*))值和胸肌亮度(L*)值(P<0.05),对其他肉品质指标无显著影响(P>0.05)。饲粮中添加0.2 mg/kg铬显著提高了热应激肉鸡胸肌pH 24 h(P<0.05),饲粮中添加铬对腿肌肉品质指标无显著影响(P>0.05)。CLA和铬互作对热应激肉鸡胸肌和腿肌肉品质指标无显著影响(P>0.05)。4)饲粮中添加CLA显著降低了热应激肉鸡的腹脂率和腿肌肌内脂肪含量(P<0.05)。饲粮中添加铬有降低热应激肉鸡腹脂率的趋势(P=0.097),但对胸肌和腿肌肌内脂肪含量均无显著影响(P>0.05)。CLA和铬互作有降低热应激肉鸡腹脂率的趋势(P=0.071),其中,1%CLA+0.2 mg/kg铬组合降低腹脂率效果最好。5)饲粮中添加CLA和铬均显著提高了热应激肉鸡肝脏铬含量(P<0.05),且CLA和铬互作对热应激肉鸡肝脏铬含量有显著影响(P<0.05)。由此可见,饲粮中添加CLA对热应激肉鸡生长性能无显著影响,但改善了肉鸡的胴体性能并促进了肝脏中铬沉积;饲粮中添加铬对热应激肉鸡生长性能、胴体性能均无显著影响,但提高了胸肌pH_(24h),并有降低腹脂率的趋势;CLA和铬互作有降低腹脂率的趋势,以1%CLA+0.2 mg/kg铬组合效果较好。

This experiment was conducted to investigate the effects of conjugated linoleic acid(CLA)and chromium(chromium propionate)on growth performance,carcass performance,meat quality and fat deposition of heat-stressed broilers.A 2×3 two factor randomized experiment design was adopted,and set 2 CLA levels(0 and 1%)and 3 chromium levels(0,0.2 and 0.4 mg/kg).A total of 216 one-day-old female broiler chicks(Cobb 500)were randomly divided into 6 groups with 6 replicates per group and 6 broilers per replicate.The ambient temperature was maintained at 32 to 34℃,and the temperature of broilers(anal temperature)was measured every weekend to ensure that they were in a state of heat stress.The experiment lasted for 42 days.The results showed as follows:1)dietary CLA and chromium and their interaction had no significant effects on the average daily feed intake,average daily gain and feed to gain ratio of heat-stressed broilers(P>0.05).2)Dietary CLA significantly increased the leg muscle percentage of heat-stressed broilers(P<0.05),and had a tendency to increase the dressing percentage(P=0.071),but had no significant effects on the breast muscle percentage and eviscerating percentage(P>0.05).Dietary chromium had a tendency to decrease the breast muscle percentage of heat-stressed broilers(P=0.099).The interaction between CLA and chromium had no significant effects on the carcass performance of heat-stressed broilers(P>0.05).3)Dietary CLA significantly decreased the yellowness(b^(*))value in breast muscle and leg muscle and brightness(L*)value in breast muscle of heat-stressed broilers(P<0.05),but had no significant effects on the other meat quality indexes(P>0.05).Dietary 0.2 mg/kg chromium significantly increased the pH 24 h in breast muscle,and dietary chromium had no significant effects on the leg muscle meat quality indexes(P>0.05).The interaction between CLA and chromium had no significant effects on the indexes of meat quality in breast muscle and leg muscle of heat-stressed broilers(P>0.05).4)Dietary CLA significantly decreased the abdominal fat percentage and leg muscle intramuscular fat content of heat-stressed broilers(P<0.05).Dietary chromium had a tendency to decrease the abdominal fat percentage of heat-stressed broilers(P=0.097),but had no significant effects on the contents of intramuscular fat in breast muscle and leg muscle(P>0.05).The interaction between CLA and chromium had a tendency to decrease the abdominal fat percentage of heat-stressed broilers(P=0.071),among them,1%CLA+0.2 mg/kg chromium combination had the best effect.5)Dietary CLA and chromium significantly increased the liver chromium content of heat-stressed broilers(P<0.05).The interaction between CLA and chromium had significant effects on the liver chromium content of heat-stressed broilers(P<0.05).In conclusion,dietary CLA have no significant effects on the growth performance of heat-stressed broilers,but improve the carcass performance and promote the deposition of chromium in live;dietary chromium have no significant effects on the growth performance and carcass performance of heat-stressed broilers,but increase the pH_(24h) in breast muscle,and tend to reduce the abdominal fat percentage;the interaction between CLA and chromium tend to reduce the abdominal fat percentage,and 1%CLA+0.2 mg/kg chromium combination has the best effect.