不同能量摄入水平对围产期奶牛肝MTP mRNA丰度的影响

Effects of different energy intakes on abundance of MTP mRNA in liver of periparturient dairy cows

将年龄、胎次相同，年产奶量大于7000kg的围产期荷斯坦奶牛30头随机分为3组，每组10头，低能量组（Ⅰ组）按中国奶牛营养标准2000年版减少20％日粮（能量摄入80％），高能量组（Ⅱ组）则按此标准增加20％日粮（能量摄入120％），对照组（Ⅲ组）按标准日粮（能量摄入100％）饲喂，试验从产前28d到产后56d结束，分娩后各组均按标准配制相同的泌乳日粮。分别于产前28、14d及产后1、14、28、56d采取肝活体组织。应用内对照RT—PCR方法检测肝脏组织MTPmRNA丰度。结果显示，各组奶牛肝MTPmRNA丰度均呈现先升高后降低的趋势。产后均高于产前，且产后1～28d差异显著（P〈0．01或P〈0．05），而后回降，至56d趋于平稳（P〉0．05）；Ⅲ组肝MTP mRNA丰度在产后1d达到峰值，而Ⅰ组和Ⅱ组在产后14d达到最大值（P〈0．01）；Ⅱ组产后1～28d显著高于I组。产后14d显著高于Ⅲ组（P〈0．01）；Ⅲ组产后1d和28d显著高于Ⅰ组（P〈0．01或P〈0．05）。这些结果表明，围产期奶牛能量摄入水平对肝MTP mRNA丰度有显著影响。

The objective was to determine a correlation between energy intakes and abundance of MTP mRNA in liver of periparturient dairy cows by method of interior comparison RT-PCR. On day 28 before parturition,thirty health multiparous periparturient Hostein cows were allocated randomly into three groups, which were fed with 80% energy diet （China Dairy Cow Raise Standard 2000 Diet）, 100% energy diet and 120% energy diet, respectively. After parturition,all the cows were offered with the criteria diet. The result showed that the relative abun- dance of MTP mRNA in liver from all the treated cows tended to a gradual increasing during last two weeks gesta- tion, reached a peak from 1 d to 14 d after parturition, and then fell after a raise. Abundance of MTP mRNA in liver of the cows fed with 120% energy diet was significantly higher than that of the cows fed with 80% energy diet during day 1 to 56 postpartum, and than that of the cows fed with 100% energy diet at day 14 postpartum （P〈0.01）. Abundance of MTP mRNA in liver of the cows fed with 100% energy diets was significantly higher than thatof the cows fed with 80% energy diet at day 1 and 28 postpartum （P〈0.01 or P〈0.05）. It was concluded that dietary energy density during dry milk could impact the abundance of MTP mRNA in liver of early lactation COWS.