烟酸铬与氯化钾对热应激肉牛生理及生产性能的影响

Effects of chromium nicotinate and potassium chloride on physiological and growth performance of heat-stressed beef cattle

为探明烟酸铬与氯化钾对热应激肉牛生产性能及生理指标的影响,该研究选用40头体重、月龄、平均日增重相近的西门塔尔杂交二代肉牛,随机分为4组,A组饲喂基础日粮（对照）、B组每头饲喂基础日粮＋烟酸铬33 mg/d、C组每头饲喂基础日粮＋氯化钾40 g/d、D组每头饲喂基础日粮＋烟酸铬33 mg/d＋氯化钾40 g/d,进行67 d的营养调控试验（预试期7 d,正试期60 d）。于每日5∶30、14∶00测定畜舍的温度、湿度和供试牛的基本生理指标,定期测定每头试验牛的采食量和体重。结果显示：①B组牛试验前期（1~30 d）和试验后期（31~60 d）14∶00的呼吸频率显著或极显著高于对照组（P〈0.05或P〈0.01）,B组平均日增重、平均日采食量和经济效益分别比对照组提高了26.85%（P〈0.01）、1.46%（P〉0.05）和89.32%;②C组牛试验前期（1~30 d）14∶00的呼吸频率和直肠温度分别较对照组的呼吸频率和直肠温度显著降低（P〈0.05）,且平均日增重和经济效益分别比对照组提高了25.93%（P〈0.05）和75.43%;③D组牛的呼吸频率、直肠温度、平均日采食量和平均日增重均与对照组差异不显著（P〉0.05）。表明在热应激肉牛日粮中每头分别添加烟酸铬33 mg/d和氯化钾40 g/d,其平均日增重、平均日采食量以及经济效益均明显提高,但同时饲喂二者时,试验牛的生理指标及生产性能并无显著变化。

To determine the effects of chromium nicotinate and potassium chloride on physiological indices and growth performance of heat-stressed beef cattle,forty crossbred beef cattle with similar body weight and age were divided into control group A（served with control diet）,experimental group B（served with control diet ＋ 33 mg/d chromium nicotinate）,experimental group C（served with control diet ＋ 40 g/d potassium chloride）,and experimental group D（served with control diet ＋33 mg/d chromium nicotinate ＋ 40 g/d potassium chloride）.The respiratory rate and rectal temperature of beef cattle were measured everyday for 67 d（pre-experiment,7 d;experiment,60 d）.Body weight of heat-stressed beef cattle was measured at the beginning and the end of experiment.Feed intake of heat-stressed beef cattle was measured every five days.The respiratory rate of heat-stressed beef cattle was greater for experimental group B than that for control group（P0.05）.Compared with control group,the average daily gain,the feed intake and the economic benefit of group B cattle were improved by 26.85%（P0.01）,1.46%（P0.05）,89.32%,respectively.The respiratory rate and rectal temperature of heat-stressed beef cattle in experimental group C were lower than that in control group,respectively,however,the average daily feed intake,daily weight gain and the economic benefit were improved by 1.23%（P0.05）,25.93%（P0.05）,and 75.43%,respectively.The respiratory rate,rectal temperature,the average daily gain,the feed intake and the economic benefit of heat-stressed beef cattle did not differ between experimental group D and control group（P0.05）.In conclusion,the average daily weight gain,the feed intake and the economic benefit of heat-stressed beef cattle were improved by offering 33 mg/d chromium nicotinate or 40g/d potassium chloride,but no influences were found by offering 33mg/d chromium nicotinate and 40 g/d potassium chloride on the growth performance and physiological indices of heat-stressed beef cattle.