过瘤胃烟酸对南方热应激中国荷斯坦牛采食量、生产性能和血液生理生化指标的影响

Effects of rumen⁃protected niacin on feed intake,performance and blood physiological and biochemical indexes of Chinese Holstein dairy cows under heat stress in southern China

【目的】研究饲粮中添加过瘤胃烟酸对南方中国荷斯坦牛热应激环境下采食量、生产性能和血液生理生化指标的影响。【方法】选择286头处于泌乳盛期中国荷斯坦牛作为试验对象,对照组饲喂基础日粮,试验组饲喂添加每天20 g/头过瘤胃烟酸的基础日粮。试验预饲期7 d,正式试验期30 d。【结果】试验期内牛舍白天平均热应激指数为76.21,全程处于热应激环境下;南方中国荷斯坦牛采食量较对照组每天显著提高了3.83 kg/头(P<0.05),日产奶量提高了2.46 kg(P>0.05),乳脂率提高了0.06%(P>0.05),乳蛋白率提高了0.07%(P>0.05),体细胞评分极显著下降了1.26分(P<0.01);51项血液生理生化指标中,大型血小板比率、白蛋白和葡萄糖等3项指标发生了显著(P<0.05)或极显著(P<0.01)变化。【结论】基础日粮中添加每天20 g/头的过瘤胃烟酸可以缓解南方中国荷斯坦牛的热应激症状,有助于其适应我国南方夏季潮湿炎热的环境。

【Objective】To investigate the effect of rumen-protected niacin(RPN)on feed intake,perfor‐mance and blood physiological and biochemical indexes of southern dairy cows under heat stress.【Method】286 Chinese Holstein cows in the peak lactation period were selected as the test subjects.The control group was fed a basic diet,and the experimental group was fed a basic diet supplemented with 20 g per head of ru‐men bypass niacin per day.The experimental pre-feeding period is 7 days,and the formal test period is 30 days.【Result】The average heat stress index was 76.21 during the day,which was under heat stress during the whole process.Compared with the control group,the feed intake of southern Chinese Holstein was significantly increased by 3.83 kg/head per day(P<0.05),the daily milk yield increased by 2.46 kg(P>0.05),the milk fat rate increased by 0.06%(P>0.05),the milk protein rate increased by 0.07%(P>0.05),and the somatic cell score decreased by 1.26 points(P<0.01).Among the 51 blood physiological and biochemical indexes,large platelet ratio,albumin and glucose had significant(P<0.05)or extremely significant(P<0.01)changes.【Conclusion】The rumen protected nicotinic acid(20 g/head per day)could alleviate the heat stress symptoms of southern Chinese Holstein cattle,and help them adapt to the hot and humid environment in southern China in the summer.