叶酸对泌乳牛产奶性能和瘤胃发酵的影响

Effects of folic acid on milk performance and rumen fermentation in lactating cows

为研究叶酸对泌乳牛产奶性能、瘤胃发酵、纤维分解菌数量和酶活力的影响,选取36头荷斯坦泌乳牛,按随机区组设计分为4组,进行100 d的饲养试验,各组(对照、LFA、MFA和HFA组)叶酸添加量分别为0、35、70和105 mg/d。结果表明,各组泌乳牛干物质采食量和体重变化无显著差异;叶酸添加组产奶量显著高于对照组(P<0.05);MFA和HFA组乳脂率显著高于LFA和对照组(P<0.05);MFA组乳蛋白率显著高于其余各组(P<0.05);各组乳糖率无显著差异;MFA和HFA组料奶比显著低于对照组(P<0.05)。叶酸添加组瘤胃pH值显著低于对照组(P<0.05),总挥发性脂肪酸和乙酸浓度显著高于对照组(P<0.05);各组丙酸浓度无显著差异;MFA和HFA组乙酸/丙酸显著高于对照组(P<0.05)。MFA和HFA组羧甲基纤维素酶和纤维二糖酶活性及溶纤维丁酸弧菌和黄色瘤胃球菌数量显著高于对照组(P<0.05);叶酸添加组木聚糖酶、果胶酶和α-淀粉酶活性与白色瘤胃球菌和产琥珀酸丝状杆菌数量显著高于对照组(P<0.05)。叶酸促进了纤维分解菌的生长,改善了瘤胃发酵,提高了泌乳牛产奶性能;其最佳添加水平为70 mg/d。

In order to study the effects of folic acid(FA) supplementation on milk performance,rumen fermentation,cellulolytic bacteria quantity and enzyme activity in lactating cows,36 multiparous Chinese Holstein cows were selected and divided into 4 groups according to a randomized block design for 100 days of feeding experiments.Folic acid supplementation amounts of 0,35,70 and 105 mg/d were obtained per cow for each group(control group,LFA group,MFA group and HFA group).The results showed that there was no significant difference in dry matter intake and body weight of lactating cows.The milk yield of folic acid supplementation group was significantly higher than that of control group(P<0.05).The milk fat rate of MFA and HFA group was significantly higher than that of LFA and control group(P<0.05).The milk protein rate in MFA group was significantly higher than that in other groups(P<0.05).There was no significant difference in lactose content between the two groups.The feed-milk ratio of MFA and HFA group was significantly lower than that of control group(P<0.05).The rumen pH value of folic acid supplementation group was significantly lower than that of the control group(P<0.05),and the concentration of total volatile fatty acids and acetic acid was significantly higher than that of the control group(P<0.05).There was no significant difference in propionic acid concentration between groups.The acetic acid/propionic acid in the MFA and HFA groups was significantly higher than that in the control group.The activity of carboxymethyl cellulase and cellobiase as well as the number of soluble fibrinolytic vibrio and yellow rumen coccus in the MFA and HFA groups were significantly higher than those in the control group(P<0.05).The activities of xylanase,pectinase and α-amylase as well as quantity of ruminococcus albus and F.succinogenes in the folic acid supplemental group were significantly higher than those in the control group(P<0.05).Folic acid promoted the growth of cellulolytic bacteria,improved rumen fermentation and the performance of lactating cows.The optimal addition level was 70 mg/d per cow.