A total of 40 Chinese Holstein cows were randomly divided into 4 groups according to birth, milk yield and similar lactation. The cows in 4 groups were fed with basic diet, basic diet plus 200, 300, 400 mg/d Daidzein respectively. The experimental period was 60 days. Blood samples were collected on Day 0, 10, 30, 60 of experiment via tail vein to isolate serum, and the levels of glucose, triglyceride and total cholesterol in the serum were measured. The results showed that, compared with the control group, the levels of serum glucose in test groupⅠandⅡcows had no signiifcant changes and the groupⅢwas signiifcantly higher than those in the control group after 60 days (P<0.05). Triglyceride content in all groups made no signiifcance among them (P>0.05). Although the levels of serum total cholesterol were dramatically decreased in the experimental groups (P< 0.05 or P< 0.01) compared with the control group, the levels among these Daidzein groups has no signiifcant changes (P>0.05). Our data suggest that Daidzein has positive effects on enhancing the body adaptability and resistance to heat stress.%选择40头产奶量、胎次、泌乳期相近的荷斯坦牛，随机分为对照组、试验Ⅰ组、试验Ⅱ组、试验Ⅲ组（n=10）。预饲1周后，分别在各组奶牛基础日粮中添加0、200mg、300mg、400mg的大豆黄酮（DA），连续60d。试验开始时及第10、30、60天尾静脉采血，测定血清中葡萄糖（Glu）、甘油三酯（TG）、总胆固醇（TC）含量。结果表明，第60天时试验Ⅲ组血清Glu含量显著高于对照组（P＜0.05）；各组之间血清中TG含量无显著差异（P＞0.05）；3个试验组血清TC含量与对照组相比显著（P＜0.05）或极显著（P＜0.01）降低，但各试验组间差异不显著（P>0.05）。说明DA可通过改变糖及脂肪代谢来增强奶牛对热应激的耐受能力。
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