大豆异黄酮对奶牛泌乳性能、血液免疫及抗氧化指标的影响

为了研究日粮中不同水平大豆异黄酮对泌乳奶牛生产性能、血液免疫及抗氧化指标的影响，试验采用单因素随机分组设计，将24头泌乳中后期‘荷斯坦奶牛’平均分为4组，进行为期42天的饲养试验。4个组中A组为对照组，B、C、D组在全混合日粮的基础上分别添加10、20和30 mg/kg的大豆异黄酮。于试验第1、14、21、28、35、42天分别按照早晚奶样的6:4比例混合后进行奶样采集，记录产奶量，并进行DHI报告分析，同时对血样进行血常规及血清指标测定。结果表明大豆异黄酮能显著提高奶牛产奶量。饲喂30 mg/kg大豆异黄酮的奶牛第42天的产奶量与同期对照组相比提升了21.8%(P<0.05)，乳蛋白含量和乳脂率无显著变化。大豆异黄酮可以减少乳中淋巴细胞和单核细胞分布，对多形核白细胞(PMN)的数量分布无显著影响。饲喂大豆异黄酮28天后，奶牛血液中红细胞数(RBC)的数量开始显著提升(P<0.05)，但白细胞数(WBC)变化不明显。试验28天后血清中白介素4(IL-4)表达水平有显著提高(P<0.05)，35天后抗氧化指标谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(T-SOD)酶活性均有显著提高(P<0.05)。试验结果表明在日粮中添加大豆异黄酮能增加奶牛的IL-4水平和抗氧化酶活性，并改善奶牛的产奶性能。

Effect of Soy Isoflavones on Lactating Performance, hematogenic immunity and antioxidative activity of Dairy Cows

The research aimed to study the effect of soy isoflavones on lactating performance, antioxidant capability and immune functions of dairy cows. A single factor design was used, 24 ‘Holstein cows’ were divided into 4 groups randomly. Set group A as the control group, group B, C and D as test groups. Cows in group B, C and D were fed by total mixed ration adding 10, 20, 30 mg/kg soy isoflavones respectively. Milk and blood samples were collected at the 1st, 14th, 21st, 28th, 35th and 42nd days. The results showed that soy isoflavones could significantly enhance milk yield, especially group D whose milk yield increased 21.8% (P<0.05) after 42 days. But no continuable and significant change showed in milk protein rate and butter-fat rate. Lymphocytes and monocytes were significantly reduced but the amount of PMN did not change. The amount of RBC significantly increased (P<0.05) after 28 days while the amount of WBC did not show obviously change. After feeding soy isoflavones for 28 days, the expression of IL-4 in serum enhanced significantly (P<0.05). Soy isoflavones could significantly enhanc the activity of GSH-Px and T-SOD after 35 days (P<0.05). It could be concluded that SI could improve the lactation performance, enhance the immune function and activities of antioxidant enzyme.