柴胡提取物对热应激奶牛生产性能和血液代谢的影响

摘要

为了研究日粮中添加不同剂量的柴胡(Radix bupleuri)提取物对热应激奶牛生理指标、生产性能和血液代谢的影响,采用完全随机区组试验设计,根据产奶量、泌乳天数、胎次将48头健康的泌乳后期荷斯坦奶牛随机分为4组,每组12头,在基础日粮中分别添加0、0.5、2.5、5.0 g·kg-1的柴胡提取物,试验期10周.结果表明,添加柴胡提取物对直肠温度、采食量、产奶量、乳蛋白产量和体细胞评分呈二次方程的影响(P〈0.05),采食量、产奶量和乳蛋白产量在0.5 g·kg-1添加水平时数值最大,直肠温度和体细胞评分在0.5 g·kg-1添加水平时数值最小.随着柴胡提取物添加剂量的增加,乳尿素氮、乳脂率、总固形物和血液中白蛋白、尿素氮、总胆固醇、高密度脂蛋白胆固醇和β-羟丁酸浓度均线性降低(P〈0.05),甘油三酯浓度线性增加(P〈0.01).与对照组相比,2.5和5.0 g·kg-1组的血浆尿素氮浓度显著增高(P=0.05),5.0 g·kg-1组的总胆固醇和高密度脂蛋白胆固醇浓度显著高于对照组和0.5 g·kg-1组.因此,本研究建议柴胡提取物在热应激奶牛上的适宜用量为0.5 g·kg-1,低于5.0 g·kg-1的剂量为安全用量.%This experiment was conducted to evaluate the effects of Bupleurum extract (BE)on the perform-ance and blood metabolism in dairy cows under heat stress.Forty-eight lactating Holstein cows were randomly assigned to one of four 2.5 treatments based on their dry matter intake (DMI),milk yield,and parity.Treat-ments consisted of 0,0.5,2.5 and 5.0 g·kg-1 BE,supplemented over a trial period of 10 weeks.Supplementa-tion of BE affected the rectal temperature,DMI,milk yield,milk protein yield,and somatic cell score of the test subjects in a quadratic manner,and the peak values were reached at a dose of 0.5 g·kg-1 BE.Milk urea nitrogen concentration,milk fat,total solid content,and blood urea nitrogen,albumin,total cholesterol,high-density lipoprotein cholesterol,andβ-hydroxybutyricacid were decreased (P〈0.05)linearly,and triglyceride was increased (P〈0.05)linearly with increasing BE doses.Compared to the control,the blood urea nitrogen concentration increased (P=0.05)in cows fed 2.5 or 5.0 g·kg-1 of BE.Compared to cows fed 0 or 0.5 g·kg-1 of BE,serum total cholesterol and high-density lipoprotein cholesterol levels increased in cows fed 5 .0 g·kg-1 of BE.Therefore,the appropriate supplemental BE level for heat-stressed dairy cows is 0.5 g·kg-1 , and the safe dosage of BE is no more than 5 .0 g·kg-1 .