饲粮添加钴胺素对荷斯坦奶牛泌乳性能、瘤胃发酵和肝脏糖异生的影响

Effects of Dietary Cobalamin on Lactation Performance,Rumen Fermentation and Liver Gluconogenesis of Holstein Dairy Cows

本试验旨在研究饲粮添加钴胺素对荷斯坦奶牛泌乳性能、瘤胃发酵和肝脏糖异生的影响。选取体重[(652.0±42.5)kg]、胎次[(2.04±0.39)胎]、泌乳天数[(104.7±31.2)d]和平均产奶量[(33.6±18.7)kg/d]相近的荷斯坦奶牛60头,依据随机区组设计分为4组(每组15头牛),分别以包被钴胺素(CCA)的形式补充0(对照组)、6(LCCA组)、12(MCCA组)和18 mg/d(HCCA组)的钴胺素。预试期20 d,正试期60 d。结果表明:随着CCA添加水平的提高,1)奶牛体重变化无显著差异(P>0.05),干物质采食量呈线性降低(P<0.05),4%乳脂校正乳和各乳成分(乳脂肪、乳蛋白质和乳糖)产量以及饲料效率呈线性提高(P<0.05);2)瘤胃pH无显著变化(P>0.05),瘤胃总挥发性脂肪酸含量和丙酸摩尔百分比呈线性提高(P<0.05),瘤胃乙酸摩尔百分和乙酸/丙酸值呈线性降低(P<0.05);3)瘤胃嗜淀粉瘤胃杆菌、栖瘤胃普雷沃氏菌、溶纤维丁酸弧菌、白色瘤胃球菌、黄色瘤胃球菌、总真菌和总原虫数量呈线性增加(P<0.05),瘤胃产琥珀酸丝状杆菌和总细菌数量呈二次变化(P<0.05);4)血清葡萄糖、总蛋白、白蛋白、胰岛素和钴胺素含量呈线性提高(P<0.05),血清尿素氮、甘油三酯、非酯化脂肪酸和β-羟丁酸含量无显著变化(P>0.05);5)肝脏甲基丙二酰辅酶A变位酶、丙酮酸羧化酶和磷酸烯醇式丙酮酸激酶活性和钴胺素含量呈线性提高(P<0.05),肝脏葡萄糖-6-酸酶活性、果糖-1,6-二磷酸酶活性和糖原含量无显著变化(P>0.05)。由此可见,饲粮添加CCA提高了奶牛泌乳性能、瘤胃丙酸含量和肝脏糖异生关键酶活性,推荐奶牛饲粮中以CCA形式补充钴胺素的添加水平为12 mg/d。

This experiment was conducted to investigate the effects of dietary cobalamin on lactation performance,rumen fermentation and liver gluconogenesis of Holstein dairy cows.Sixty Holstein dairy cows with similar body weight of(652.0±42.5)kg,parity of(2.04±0.39),lactation days of(104.7±31.2)and average milk yield of(33.6±18.7)kg/d were divided into 4 groups(15 cows per group)according to random block design,and the cobalamin was supplemented with 0(control group),6(LCCA group),12(MCCA group)and 18 mg/d(HCCA group)in the form of coated cobalamin(CCA),respectively.The pre-trial period lasted for 20 days and the experimental period lasted for 60 days.The results showed as follows,with the increase of CCA supplemental level:1)there was no significant difference in the body weight change of dairy cows(P>0.05),the dry matter intake was linearly decreased(P<0.05),and the yields of 4%fat correction milk and milk components(milk fat,milk protein and lactose)and feed efficiency were linearly increased(P<0.05);2)the pH in rumen had no significant change(P>0.05),the total volatile fatty acid content and propionate molar percentage in rumen were linearly increased(P<0.05),and the acetate molar percentage and acetate to propionate ratio in rumen were linearly decreased(P<0.05);3)the numbers of Ruminobacter amylophilus,Prevotella ruminicola,Butyrivibrio fibrisolvens,Ruminococcus albus,Ruminococcus flavefaciens,total fungi and total protozoa in rumen were increased linearly(P<0.05),while the numbers of Fibrobacter succinogenes and total bacteria in rumen were quadraticly changed(P<0.05);4)the contents of glucose,total protein,albumin,insulin and cobalamin in serum were linearly increased(P<0.05),while the contents of urea nitrogen,triglyceride,non-esterification fatty acid and β-hydroxybutyrate in serum had no significant changes(P>0.05);5)the activities of methylmalonyl-coenzyme A mutase,pyruvate carboxylase and phosphoenolpyruvate carboxykinase and the cobalamin content in liver were linearly increased(P<0.05),while the activities of glucose-6-phosphatase,fructose-1,6-bisphosphatase and glycogen content in liver had no significant changes(P>0.05).In conclusion,dietary CCA can improve lactation performance,rumen propionate content and liver gluconogenic key enzyme activities of dairy cows,and it is recommended that the supplemental level of cobalamin in the form of CCA is 12 mg/d in dairy cow diets.