摄入不同能量的围产期乳牛肝低密度脂蛋白受体 mRNA丰度的比较

将30头健康、经产、处于围产期的黑白花乳牛随机分为3组,每组10头。从产前28 d开始,低能量组乳牛饲喂《中国奶牛饲养标准(2000)》减少20%日粮(能量摄入80%),对照组乳牛饲喂《标准》日粮(能量摄入100%),高能量组乳牛饲喂《标准》增加20%日粮(能量摄入120%),产后各组乳牛均饲喂标准日粮,至产后第56 d结束试验;采用内对照RT-PCR方法检测摄入不同能量的围产期乳牛肝活体组织低密度脂蛋白受体(LDLR)mRNA丰度。结果,不同能量组乳牛肝LDLR mRNA丰度产前至产后均呈现先升高后降低的趋势,100%和120%能量组肝LDLRmRNA丰度在产后14 d达最大值,且产后均高于产前(产后56 d除外,P<0.01或P<0.05);而80%能量组产后1 d即达到最大值,产前14 d至产后14 d,LDLR mRNA相对表达量显著高于100%和120%能量组;产后28~56 d,120%能量组显著高于80%和100%能量组(P<0.01)。表明围产期乳牛能量摄入水平对肝LDLR mRNA丰度有显著影响。

Comparison of abundance of LDLR mRNA in liver of periparturient dairy cows intaking different energy

On day 28 before parturition,30 healthy multiparous periparturient Hostein cows were allocated randomly into three groups fed with 100% energy diet(China Dairy Cow Raise Standard 2000 Diet),120% energy diet and 80% energy diet,respectively.After parturition,all the cows were offered with the criteria diet for 56 days.Aroundparturition,significantly increasing the relative expression of low density lipoprotein receptor(LDLR) mRNA was observed in liver sampled from dairy cows fed with 80% energy diets,and maximized on day 1 post-parturition,but decreased by 65.2% on day 28 post-parturition.(Abundance) of LDLR mRNA in liver of the cows fed with 80% energy diet was significantly higher than that of the cows fed with 100% and 120%energy diet from day 14 before parturition to day 14 post-(parturition)(P<0.01),and the relative expression of LDLR mRNA during antepartum was significantly higher in all groupsthan that during postpartum(except from day 56 on post-parturition,P<0.01 or P<0.05).It was concluded that decreasing energy intake in the dairy cows could alleviate negative energy(balance)(around) parturition and increase expression of LDLR mRNA in liver.