本试验旨在研究大豆异黄酮对泌乳后期中国荷斯坦奶牛泌乳性能、免疫功能和乳腺肥大细胞白介素-4水平的影响。选择12头泌乳后期的荷斯坦奶牛随机分为4组，每组3个重复。对照组和A、B、C组分别添加不同水平的大豆异黄酮（0、10、20、30 mg/kg）。分离采自奶牛乳腺的肥大细胞，并分别与0、0.25、0.50、0.75 mg/mL的大豆异黄酮共育。结果表明：1)大豆异黄酮可显著减缓泌乳后期奶牛产奶量下降趋势（P<0.05），其中A、B和C组奶牛的产奶量比对照组提高7.29%、12.66%和10.13%；2)B和C组乳蛋白质率显著高于对照组（P<0.05）；3)大豆异黄酮可提高血清和乳中生长激素（GH）和催乳素（PRL）的含量，B和C组效果显著（P<0.05），显著降低生长抑素（SS）含量（P<0.05）；4)大豆异黄酮可显著提高血清（P<0.05）、乳（P<0.01）和乳腺组织（C组，P<0.05）中白介素-4（IL-4）的水平；5)0.25 mg/mL大豆异黄酮能够极显著增加奶牛乳腺肥大细胞的IL-4表达量（P<0.01）。由此可知，大豆异黄酮能够通过对乳腺免疫指标表达量的调控，提高奶牛泌乳性能，增强奶牛的免疫功能，可促进乳腺肥大细胞IL-4的分泌。

To study the effects of soybean isoflavone (SI) on lactating performance, immune function, and interleukin-4 (IL-4) expression level in mammary mast cell of late lactating dairy cows, twelve Holstein dairy cows were assigned randomly to four groups (three duplications in each group). Control group and groups A, B and C were feed different levels of SI (0, 10, 20, 30 mg/kg). Mammary mast cells were isolated from cows and cultured with different concentrations of SI (0, 0.25, 0.5, 0.75 mg/mL). The results showed as follows: 1) SI could significantly slow down the decrease of milk yield (P<0.05), and the milk yields in groups A, B and C were 4.28%, 8.40% and 9.15% higher than control group, respectively; 2) milk protein percentage in group B and C was higher than that of the control group (P<0.05); 3) GH and PRL contents in serum and milk were significantly increased by the supplementation of SI (group B and C, P<0.05), SS content decreased (P<0.05); 4) IL-4 experssion level in serum (P<0.01), milk (P<0.01) and breast issue (group C, P<0.05) were significantly increased by the supplementation of SI. 5) IL-4 experssion level of mammary mast cell was significantly increased by the supplementation of SI (0.25 mg/mL, P<0.01). It can be concluded that SI can improve the lactation performance and enhance the immune function of dairy cows through the regulation on immune factors’ expression in mammary glands and the stimulation on IL-4 secretion.［Chinese Journal of Animal Nutrition, 2010，22（6）:1679-1686］