摘要
采用4×4的拉丁方试验设计,将体重、奶产量和泌乳天数接近的4头经产荷斯坦牛饲喂四种等能量水平不同蛋白质水平(13.2%,14.1%,15.0%和16.2%,干物质基础)的日粮,来研究奶牛乳尿素氮浓度及氮利用率的变化情况。整个试验期共56d,每期14d,1-10d为调整期,11-13d为粪尿收集期。结果发现,随着日粮蛋白质水平的增加,乳尿素氮浓度极显著升高(P<0.01),而氮的利用率随着蛋白质水平的增加而显著下降(P<0.05);乳尿素氮和氮利用率间存在显著的二次曲线关系(P<0.01)。乳尿素氮可以作为反映奶牛日粮蛋白质水平变化的指标,也有可能作为估测奶牛氮利用率的指标发挥作用。
Some experiments were conducted according to a 4×4 Latin Square design. Four mature lactating Holstein cows with similar body weight, milk production and days in milk were used to evaluate the effect of dietary protein level on milk urea nitrogen and nitrogen efficiency of dairy cows. The cows were fed four different crude protein levels diets (13.2, 14.1, 15.0 and 16.2 %, DM basis) with similar net energy content. Experimental periods were 56 d, each period consisted of 14 days with d 1 to 10 for adjustment and 11 to 13 days for collection of urine and feces. The milk urea nitrogen concentration was increased significantly with the increasing protein level of diet (P〈0.01), while nitrogen efficiency was decreased significantly with the increasing protein level of diet (P〈0.05). There was a close conic relationship between MUN concentration and nitrogen efficiency (P〈0.01). The results obtained in this study suggested that MUN could be used a parameter reflect the changes in dietary protein level and might be used to estimate nitrogen efficiency of dairy cows.
出处
《乳业科学与技术》
2008年第6期266-268,265,共4页
JOURNAL OF DAIRY SCIENCE AND TECHNOLOGY
基金
国家"十五"奶业重大科技专项课题(No.2002BA518A02-02)
集美大学科研基金(No.ZQ2006027)资助
关键词
日粮蛋白质水平
乳尿素氮
氮利用率
dietary protein level
milk urea nitrogen
nitrogen efficiency