本研究旨在了解在外部热应激环境下奶牛日粮添加不同比例复合酶制剂对奶牛生产性能和经济效益的影响。选取泌乳时间、产奶量、胎次相近的荷斯坦泌乳牛60 头,随机分为对照组、试验Ⅰ组、试验Ⅱ组和试验Ⅲ组,每组15 头,在基础日粮中分别添加复合酶制剂0%、0.5%、1.0%和1.5%,测定热应激奶牛产奶量和主要乳成分变化情况,并分析复合酶制剂对奶牛养殖经济效益的影响。结果显示,在热应激状态下3 个试验组平均日产奶量均高于对照组,试验Ⅱ组显著高于对照组（P<0.05）,产奶量最高;试验Ⅱ组乳蛋白、乳糖含量显著高于对照组（P<0.05）,分别比对照组增加了5.38%、14.25%。试验Ⅱ组每头奶牛经济效益比对照组增加了6.58 元/天。在本试验条件下,在日粮中添加复合酶制剂有助于提高奶牛生产性能和经济效益,添加量为1.0%时效果较好。

The purpose of this study was to investigate the effects of different ratios of enzyme preparation in diet on performance and economic benefit of dairy cows under external heat stress. Sixty Holstein lactating cows with similar lactation times,milk yield and parity were randomly divided into control group,test I group,test II group and test III group with 15 in each group,the changes of milk yield and main milk components in heat stressed dairy cows were measured by adding 0%,0.5%,1.0% and 1.5% enzyme preparation into the basal diet,and the effects of enzyme preparation on the economic benefit of dairy cows were analyzed. The results showed that the average daily milk yield of the three groups was higher than that of the control group,the test II group was significantly higher than the control group（p<0.05） and the milk protein and lactose contents of the test II groups were significantly higher than that of the control group（p<0.05）,increased by 5.38% and 14.25% respectively. The economic benefit of test II group was 6.58 yuan per day more than that of the control group. Under the condition of this experiment,adding compound enzyme preparation to the diet was helpful to improve the performance and economic benefit of dairy cows,and the effect was better when adding 1.0%.