烟酸对热应激奶牛营养物质表观消化率及血清生化指标的影响

试验选用3头健康的泌乳后期的中国荷斯坦奶牛,采用3×3拉丁方设计,在基础日粮中分别添加0、8、15g/d烟酸,研究日粮添加不同水平烟酸对热应激奶牛干物质采食量、营养物质表观消化率和部分血液生化指标的影响。试验期为63d。结果表明:(1)添加8、15g/d烟酸分别使奶牛的干物质采食量显著提高12.71%和11.20%(P<0.05);(2)添加8g/d烟酸能使奶牛营养物质消化率显著提高(P<0.05),添加15g/d烟酸对奶牛营养物质消化率有提高的趋势,但差异不显著(P>0.05);(3)日粮添加烟酸能够维持奶牛血清皮质醇水平的基本恒定、降低血清胆固醇、甘油三酯水平的趋势。综合分析试验奶牛的干物质采食量、营养物质表观消化率和血液生化指标变化,夏季给奶牛补饲烟酸有助于缓解热应激,适宜的添加量为8g/d。

Three healthy Chinese Holstein cows in early lactation were chosen under hot environment,and a 3×3 Latin square design was used to study the effects of the basal diets supplemented with 0,8,15 g/d niacin each cow as control group,group B,group C on apparent digestibility of nutrient,dry matter intake and part of serum biochemical parameters.The feeding experiment lasted for 63 days.The results indicated：（1）Dry matter intake of group B and C was in-creased significantly by 12.71 %（P 〈 0.05）,11.20 %（P 〈 0.05）respectively,compared with control group;（2）Compared with control group,digestibility of nutrient of group B was increased significantly（P 〈 0.05）,and digestibility of nutrient of group C had the trend of increasing,but was not significantly influenced（P 〉 0.05）;（3）The serum levels of COR was sta-ble,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 dry matter intake,apparent digestibility of nutrient and serum biochemical parameters were comprehensively analysis,niacin supplementation with 8 g/d in the lactating cows diet had the best effect and could release its heat stress in hot environment.