干乳期能量摄入水平对围产期奶牛肝载脂蛋白B100mRNA丰度的影响

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。Ⅰ组饲喂中国奶牛饲养标准（2000）减少20％日粮（能量摄入80％组）。Ⅱ组饲喂中国奶牛饲养标准（2000）日粮（能量摄入100％组），Ⅲ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泌乳日粮。采用内对照RT—PCR方法，检测了干乳期摄入不同能量的围产期奶牛肝脏活体组织载脂蛋白B100（apoB100）mRNA丰度。结果表明。apoB100mRNA相对表达量，产前至产后Ⅰ、Ⅲ组均呈先升高后降低的趋势，Ⅲ组产后apoB100mRNA丰度降低了61．45％，Ⅰ组呈逐渐降低的趋势，各组均在产后28d达最低值（Ⅰ组，P〈0．05；Ⅱ、Ⅲ组，P〈0．01）。产前14d至产后1d，apoB100mRNA相对表达量Ⅲ组高于Ⅰ组，Ⅰ组高于Ⅱ组，组间差异极显著（P〈0．01）；产后28d。Ⅰ组高于Ⅱ、Ⅲ组（P〈0．05）。由此可见，围产期奶牛能量摄入水平对肝脏载脂蛋白B100mRNA丰度有显著影响。

Effects of Different Energy Intake in the Dry Period on Abundance of Apolipoprotein B100 mRNA in Liver of Periparturient Dairy Cows

The objective of this study is to determine the relationship between energy intake and abundance of apoB100mRNA in liver of periparturient dairy cows. At 28 days before parturition, thirty multiparous periparturient Holstein cows were randomly allocated 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. After parturition, decreasing the relative expression of apoB100mRNA was observed in liver sampled from dairy cows fed with 80%, 100% and 120% energy diets, especially decreased by 61.45% in 120% energy diet group , and minimized in all groups at 28 days after parturition. Abundance of apoB100mRNA in liver was significantly higher in the cows fed with 120% energy diet than in the cows fed with 80% energy diet, and was significantly higher in the cows fed with 80% energy diet than in the cows fed with 100% energy diet from 14 days before parturition to 1 days after parturition (P<0.01), and the relative expression of apoB100mRNA in the cows fed with 80% energy diet were higher than in the cows fed with 100% and 120% energy diet (P<0.05). It is concluded that increasing energy intake in the dry cows could exacerbate negative energy balance after parturition and reduce the expression of apoB100mRNA in liver ; oppositely, reducing energy intake in the dry cows could alleviate negative energy balance after parturition and increase the expression of apoB100mRNA in liver.