过瘤胃烟酸和胆碱对围产期奶牛泌乳性能和肝脂质代谢的影响

Effects of Rumen-protected Nicotinic Acid and Rumen-protected Choline on Lactation Performance and Hepatic Lipid Metabolism of Perinatal Cows

旨在研究日粮中添加过瘤胃保护烟酸(rumen-protected niacin,RPN)和过瘤胃保护胆碱(rumen-protected choline,RPC)对围产期奶牛泌乳性能和肝脂质代谢的影响,为缓解奶牛脂肪肝提供理论依据。本试验选用24头健康、胎次相近的中国荷斯坦围产期奶牛,根据2×2试验设计分为4组,每组6头。处理组分别为对照组(CON,基础日粮)、烟酸组(RPN,基础日粮+18.4 g·d^(-1)RPN)、胆碱组(RPC,基础日粮+60 g·d^(-1) RPC)、混合组(RPN×RPC,基础日粮+18.4 g·d^(-1)RPN+60 g·d^(-1) RPC)。试验期为产前14 d到产后21 d。试验期记录奶牛产后每周体重和产奶量、犊牛初生重,并采集每周血样、产后14和21 d乳样,于产后21 d活体穿刺采集肝组织样品。结果表明,添加RPN和RPC对产后奶牛体重、犊牛初生重、产奶量和乳成分无显著影响(P>0.05);添加RPN和RPC可极显著提高血浆中烟酸(niacin,NA)、胆碱(choline,CH)和极低密度脂蛋白(very low density lipoprotein,VLDL)的含量(P<0.001);单独添加RPN和同时添加RPN和RPC可显著降低肝中甘油三酯(triglycerides,TG)的含量(P<0.05)。综上所述,围产期奶牛基础日粮中添加RPN和RPC对生产性能无显著影响,但可通过显著提高血浆中VLDL的含量,降低肝中脂沉积,从而改善围产期奶牛肝和机体健康。

The objective of this study was to investigate the effects of rumen-protected nicotinic acid(RPN)and rumen-protected choline(RPC)on lactation performance and hepatic lipid metabolism of perinatal dairy cows,and to provide theoretical basis for alleviating fatty liver of dairy cows.Twenty-four healthy Chinese Holstein perinatal dairy cows with similar parity were randomly divided into 4 groups in a 2×2 factor experimental design with 6 cows in each group,including control group(CON,basal diet),RPN group(RPN,basal diet+18.4 g·d^(-1) RPN),RPC group(RPC,basal diet+60 g·d^(-1) RPC)and both RPN and RPC group(RPN×RPC,basic diet+18.4 g·d^(-1) RPN+60 g·d^(-1) RPC),respectively.The experiment was conducted from 14 d prenatal to 21 d postpartum.The weekly weight and milk production of the dairy cows after calving,and the birth weight of the calves were recorded.Blood was collected every week,milk was sampled at 14 and 21 d after delivery,liver biopsies were taken on 21 d relative to parturition.The results showed that the supplementation of RPN or RPC had no significant impact on the performance of dairy cows and calves,including dairy cows body weight,calves body weight,milk production and milk composition(P>0.05).Supplementation of RPN and RPC significantly increased the contents of nicotinic acid(NA),choline(CH)and the level of very low density lipoprotein(VLDL)in plasma(P<0.001).RPN group and RPN×RPC group significantly reduced triglycerides(TG)content in liver(P<0.05).In summary,supplementing RPN and RPC to the basic diet of perinatal dairy cows has no significant effect on production performance,whereas they can improve the liver and body health of perinatal dairy cows by increasing the content of VLDL in plasma and reduce lipid deposition in the liver.