不同水平大豆异黄酮对泌乳前期奶牛产奶量、乳品质和血液免疫指标的影响OA

This experiment was conducted to investigate the effects of dietary supplementation with different levels of soy isoflavones on milk yield,milk quality and blood immune indices of dairy cows in early lactation,and to determine the optimal supplemental level.Forty-eight healthy Holstein cows with no significant differences in parity,days in milk and initial milk yield were randomly divided into 4 groups,with 3 replicates per group and 4 cows per replicate.Cows in the control group were fed a basal total mixed ration(TMR),while those in experimental groups Ⅰ,Ⅱ and Ⅲ were supplemented with 20,30 and 50 mg/kg soy isoflavones in the basal diet,respectively.The preliminary trial period lasted 7 days,and the formal trial period lasted 60 days.During the experiment,milk production performance was recorded,milk quality indices were detected using a milk composition analyzer,and blood immune indices were determined by enzyme-linked immunosorbent assay(ELISA).The results showed that compared with the control group:(1)The average daily milk yield of the 20 mg/kg and 30 mg/kg supplementation groups over the whole experimental period was significantly increased by 11.31%and 17.44%,respectively(P＜0.05);(2)The milk protein percentage of the 20 mg/kg and 30 mg/kg groups was significantly elevated by 3.81%and 6.03%(P＜0.05),and the milk fat percentage was significantly increased by 3.43%and 5.64%,respectively(P＜0.05).The milk somatic cell count(SCC)in all supplementation groups was significantly decreased(P＜0.05);(3)The contents of serum IgG,IgA,IgM,complement C3,complement C4 and interleukin-2(IL-2)in the 30 mg/kg supplementation group were significantly increased(P＜0.05),while the serum tumor necrosis factor-α(TNF-α)content was significantly decreased(P＜0.05).In conclusion,dietary supplementation with soy isoflavones can significantly improve the production performance,milk quality and immune function of dairy cows in early lactation.Under the experimental conditions,the optimal supplemental level is recommended to be 30 mg/kg,which provides a theoretical basis and practical reference for the standardized application of soy isoflavones in large-scale dairy farming.