中文摘要：

将年龄、胎次相同，年产奶量大于5000kg的围产期健康奶牛30头随机分为3组，每组10头。低能组饲喂中国奶牛饲养标准（2000）减少20％日粮（能量摄入80％组）、对照组饲喂中国奶牛饲养标准（2000）日粮（能量摄入100％组）和高能组饲喂中国奶牛饲养标准（2000）增加20％日粮（能量摄入120％组），试验从产前28d开始至产后56d结束，产后各组奶牛均饲喂标准日粮。采用内对照RT-PCR方法检测了不同能量摄入围产期奶牛肝组织载脂蛋白E（apolipoprotein E，apoE）mRNA丰度。结果表明：apoE mRNA相对表达量从产前28d至产后56d各组均呈现先升高后降低的趋势，各组apoE mRNA水平均在产后一天达到最大值（P〈0．01），且产后均高于产前（产后56d除外）；产前14d至产后28d低能组apoE mRNA相对表达量均高于其他两组（P〈0．05或P〈0．01），高能组在产后28d和56d高于对照组（P〈0．01）。可见，围产期奶牛能量摄入水平对肝组织载脂蛋白E mRNA丰度有显著影响。

英文摘要：

The objective of this study is to determine the relationship between energy intake and abundance of apoE mRNA in liver of periparturient dairy cows. At 28 days before parturition, thirty multiparous periparturient Holstein cows were randomly divided into three groups fed with 100% energy diet （China Dairy Cow Raise Standard, 2000）, 120% energy diet and 80% energy diet, respectively. After parturition, all the cows were offered criteria day provisions until 56 days postpartum. Relative expression of apoE mRNA in liver tissue was increased by degrees before parturition, peaked at 1 day after parturition and decreased gradually after parturition in the dairy cows fed with 80%, 100% and 120% energy diets. Relative expression of apoE mRNA in liver tissue of postpartum was higher than that of antepartum in three treatments（except for 56 days after parturition）. Abundance of apoE mRNA in liver was significantly higher in the cows fed with 80% energy diet than in the cows fed with 100% and 120% energy diets from 14 days before parturition to 28 days after parturition（P〈0.05或P〈0. 01） , and was significantly higher in the cows fed with 120% energy diet than in the cows fed with 100% energy diet from 28 days to 56 days after parturition（P〈0.01）. It is concluded that increasing energy intake in the dry cows could reduce the expression of apoE mRNA in liver, oppositely, reducing energy intake in the dry cows could increase the expression of apoE mRNA in liver of periparturient dairy cows.