烟酸对热应激奶牛生产性能、血清生化指标的影响

选择健康泌乳后期的中国荷斯坦奶牛3头,采用3×3拉丁方设计,在基础日粮中分别添加0、8、15 g/(头.d)的烟酸,试验期63 d,研究了日粮中添加不同水平的烟酸对热应激奶牛生产性能、血清生化指标的影响。结果表明:烟酸对热应激状态的奶牛直肠温度和呼吸频率影响未达显著水平;日粮中添加8、15 g/(头.d)烟酸奶牛的产奶量分别比对照组提高29.9%、22.0%(P<0.05),4%标准乳产量比对照组分别提高了28.5%和21.5%(P<0.05),且不同添加水平间无显著差异(P>0.05),添加烟酸对奶牛的乳蛋白、乳脂和乳糖含量影响未达到显著水平;2个试验组都能够维持奶牛血清皮质醇水平的基本恒定,降低了胆固醇和甘油三酯的水平,但与对照组相比差异不显著(P>0.05)。综合分析表明,给热应激奶牛补饲烟酸有助于缓解热应激,烟酸适宜添加量为8 g/d。

Effects of Supplemental Niacin on the Performance and Biochemical Parameter of Serum of Heat-stressed Dairy Cows

To determine the effects of supplemental niacin on the performance,physiological and biochemical parameter of serum of heat-stressed dairy cows,an experiment was carried out using three health Chinese Holstein cows in latter lactation under hot environment.According to a 3×3 Latin square design,the basal diets supplemented with 0,8,15 g/d niacin in each cow were used as negative control group A,experimental group B,and C,which were carried out for 63 days.The results showed that supplemental niacin had no effects on the rectal temperature and respiratory rate.Compared to the negative control A,milk yield of group B and C was increased by 29.9%(P< 0.05) and 22.0%(P<0.05),respectively.The 4% fat corrected milk yield was increased by 28.5%(P<0.05) and 21.5%(P<0.05),respectively.No significant difference between group B and C(P>0.05) was observed.Dietary niacin had no effect on the content of milk fat,milk protein and milk sugar.The serum levels of COR could be kept stable,and the content of serum cholesterol and triglyceride decreased insignificantly at the Niacin level of 8 g/d and 15 g/d(P>0.05).As performance,part of serum physiological-biochemical parameters was concerned.Niacin supplementation with 8 g/d in the ration of lactating cows had the best effect and released the effect of heat stress in hot environment.