叶酸和钴胺素对围产期奶牛泌乳性能、养分消化和肝脂质含量的影响

Effects of Folic Acid and Cobalamin on Lactation Performance,Nutrient Digestion and Hepatic Lipid Content in Dairy Cows during Perinatal Period

旨在研究包被叶酸(CFA)和包被钴胺素(CCA)对围产期奶牛泌乳性能、养分消化、瘤胃发酵和肝脂质含量的影响。选取48头胎次、上一泌乳期产奶量和体重相近的围产期荷斯坦奶牛,按2×2因子、随机区组设计分为4组,对照组饲喂基础日粮,其余3组分别在基础日粮中添加CFA 6.75 g·d^(-1)、CCA 0.6 g·d^(-1)和CFA 6.75 g·d^(-1)+CCA 0.6 g·d^(-1)。试验从奶牛产前21 d开始,产后21 d结束。奶牛产后,测定体重变化(BWC)、产奶性能,采集血液、瘤胃液和肝样品。结果发现:1)补充CFA,奶牛BWC显著降低(P<0.05),饲料效率显著提高(P<0.05)。补充CFA或CCA,实际乳、乳脂校正乳(FCM)、乳脂肪和乳蛋白质产量显著提高(P<0.05)。2)补充CFA,干物质(DM)和中性洗涤纤维(NDF)表观消化率显著提高(P<0.05)。补充CCA,DM、有机物(OM)、粗蛋白质(CP)、NDF和酸性洗涤纤维(ADF)表观消化率显著提高(P<0.05)。3)补充CFA或CCA,瘤胃pH无显著变化(P>0.05),总挥发性脂肪酸(TVFA)浓度显著增加(P<0.05)。补充CFA,瘤胃乙酸浓度和乙酸/丙酸显著增加(P<0.05)。补充CCA,瘤胃丙酸浓度显著增加(P<0.05),乙酸/丙酸显著降低(P<0.05)。4)补充CFA,血液非酯化脂肪酸、β-羟丁酸(BHB)和同型半胱氨酸(Hcy)浓度显著降低,血液葡萄糖浓度无显著变化(P>0.05),叶酸(FA)浓度显著增加(P<0.05)。补充CCA,血液葡萄糖和钴胺素(CA)浓度显著增加(P<0.05)。5)补充CFA,奶牛肝中FA含量显著提高,总脂和甘油三酯(TG)含量显著降低(P<0.05);补充CCA,肝中CA含量显著提高,总脂和TG含量无显著变化(P>0.05)。6)与单独补充CFA或CCA相比,二者联合补充,奶牛FCM产量、NDF消化率和瘤胃TVFA浓度较高(P<0.05),血液Hcy和肝TG含量较低(P<0.05)。综上表明,CFA和CCA联合补充对改善围产期奶牛泌乳性能和降低肝脂质含量比单独补充更有效。

The study evaluated the effects of coated folic acid(CFA)and coated cobalamin(CCA)on the lactation performance,nutrient digestion,rumen fermentation and hepatic lipid content of dairy cows during perinatal period.Forty-eight Holstein dairy cows during perinatal period with similar parity,previous 305-d milk yield and body weight were assigned in a 2×2 factorial and randomized block design to 4 groups:cows in the control group were fed a basal diet,and those in other 3 groups were fed basal diets supplemented with CFA 6.75 g·d^(-1),CCA 0.6 g·d^(-1),and CFA 6.75 g·d^(-1)+CCA 0.6 g·d^(-1),respectively.The study started at 21 days before the excepted calving date and ended at 21 days after calving.During the postpartum 21 days,body weight change(BWC)and lactation performance were determined,and samples of blood,rumen fluid and liver tissue were collected.The results showed as follows:1)CFA addition significantly decreased the BWC(P<0.05)and significantly increased feed efficiency(P<0.05).The yields of actual milk,4%fat-corrected milk(FCM),milk fat and milk protein significantly increased(P<0.05)with CFA or CCA addition.2)The apparent digestibility of dry matter(DM)and neutral detergent fiber(NDF)increased significantly(P<0.05)with CFA addition.The apparent digestibility of DM,organic matter(OM),crude protein(CP),NDF and acid detergent fiber(ADF)significantly increased with CCA addition(P<0.05).3)Rumen pH was not significantly changed(P>0.05),but total volatile fatty acids(TVFA)concentration increased(P<0.05)with CFA or CCA addition.Rumen acetate concentration and acetate to propionate ratio increased significantly(P<0.05)with CFA addition.Rumen propionate concentration increased significantly(P<0.05),while acetate to propionate ratio decreased significantly(P<0.05)with CCA addition.4)Blood nonesterified fatty acids,β-hydroxybutyrate(BHB)and homocysteine(Hcy)contents decreased(P<0.05)with CFA addition.Blood glucose content was not significantly changed(P>0.05),but folate(FA)content increased significantly(P<0.05)with CFA addition.Blood glucose and cobalamin(CA)contents increased significantly(P<0.05)with CCA addition.5)Hepatic FA content increased significantly(P<0.05),and total lipid and triglyceride(TG)contents decreased significantly(P<0.05)with CFA addition.Hepatic CA content increased significantly(P<0.05),but total lipid and TG contents were not significantly changed(P>0.05)with CCA addition.6)When compared with CFA or CCA addition alone,the FCM yield,NDF digestibility and rumen TVFA concentration were greater(P<0.05),and blood Hcy and hepatic TG contents were lower for cows receiving CFA and CCA together.In conclusion,addition of CFA and CCA together is more effective in improving lactation performance and reducing hepatic lipid content compared with CFA or CCA addition alone.