高温下日粮铬水平对肉鸡生长性能和血液生化指标的影响

EFFECTS OF DIETARY CHROMIUM LEVELS ON PERFORMANCE, SERUM TRAITS OF BROILERS UNDER HEAT STRESS

试验1 :选用72只体重接近的28日龄肉鸡随机分成4组 ,各组铬的添加量分别为0、200、400、600μg/kg(以吡啶羧酸铬形式) ,试鸡饲养于人工气候舱中 ,舱温为25～33℃ ,试验期2周。试验结果表明 :1.日粮中添加600μg/kg 的铬 ,与对照组相比 ,42日龄肉鸡体重提高10.7 %(P<0.05) ,日增重提高13.7 %(P<0.05) ,而对日采食量、饲料转化率无显著影响。2.日粮补铬对血清T3、T4、葡萄糖、甘油三酯、胆固醇含量没有显著影响 ,而使血清总蛋白水平升高 ,尿素氮水平下降(P<0.05)。试验2 :选用500只体重接近的21日龄肉鸡随机分成5组 ,铬添加量分别为0、200、400、600和800μg/kg(以吡啶羧酸铬形式) ,试鸡饲养于夏季鸡舍中 ,日温度在30～35℃之间 ,试验期5周。试验结果表明 ,日粮中添加Cr800μg/kg,使56日龄肉鸡体重、日增重、饲料转化率分别提高7.5 %、11.9 %、6.2 % ,但都不显著 ,表明给饲养于高温条件(30～35℃)下肉鸡补铬有提高增重和饲料转化率的趋势。

Trial 1. In artificial climate chambers, seventy two 28-day-old broiler chicks were randomly divided into 4 groups:Ⅰ,baseal diet(B);Ⅱ,B+200μg/kg Cr as chromium picolinate(Crp);Ⅲ,B+400μg/kg Cr as Crp;Ⅳ,B+600μg/kg Cr as Crp .The temperature of artificial climate chambers was maintained within 25°Cto 33°C for 2 weeks.Dietary Cr addition at 600μ g/kg increased body weigh by 10.7%(P<0.05),but didn't affect daily feed intake and feed efficiency. Cr supplementation didn't influence serum T3,T4 content while reduced serum urea N content (P<0.05). Trial 2.In summer,five hundred 21-day-old broiler chicks were randomly assigned to 5 treatments: Ⅰ, basal diet (B);Ⅱ, B+200μg/kg Cr as Crp;Ⅲ,B+400μg/kg Cr;Ⅳ,B+600μg/kg Cr;Ⅴ,B+800μg/kg Cr .The temperature of the chick house was maintained within 30 to 35°C. Body weight gain ,daily weight gain and feed efficiency of the broiler chicks fed basal diet supplemented with 800μg/kg Cr were increased (P>0.15)by 7.5%,11.9%,6.2%,respectively.