过瘤胃蛋氨酸对奶牛瘤胃体外发酵及泌乳奶牛生产性能的影响

摘要

本文主要研究过瘤胃蛋氨酸对奶牛瘤胃体外发酵及泌乳奶牛生产性能的影响. 体外发酵试验:分别在培养液中添加蛋氨酸、过瘤胃蛋氨酸,以无添加为对照,在培养0、2、4、8、12、16和24 h测定pH以及氨态氮、细菌蛋白和原虫蛋白含量;动物试验:选用30头健康的泌乳荷斯坦奶牛采用随机区组分为3组,分别在基础饲粮中添加13.50 g/(头·d)蛋氨酸、30.00 g/(头·d)过瘤胃蛋氨酸,以无添加为对照. 预试期7 d,正试期42 d. 结果表明:1)体外发酵试验,培养液pH、氨态氮和细菌蛋白含量在组间都没有显著差异( P>0.05);与对照组相比,过瘤胃蛋氨酸组和蛋氨酸组均显著提高了培养液原虫蛋白含量(P<0.05),但2个试验组间没有显著差异(P>0.05). 2)动物试验,第28天时,以及乳蛋白率和乳脂率在3组间都没有显著的差异( P>0.05).第42天时,过瘤胃蛋氨酸组的乳蛋白率和乳脂率显著高于其他2组( P<0.05) ,而该组的血清尿素氮和乳尿素氮含量显著低于其他2组( P<0.05);另外,该组的饲粮粗蛋白质消化率也显著高于其他2组( P<0.05). 综上,过瘤胃蛋氨酸对奶牛瘤胃体外发酵没有显著影响,但可在一定程度上提高奶牛乳蛋白率和乳脂率和饲粮粗蛋白质的消化率.%This experiment was conducted to study the effects of rumen protected methionine on in vitro rumi-nal fermentation and performance of lactating dairy cows. In vitro fermentation test, methionine and rumen pro-tected methionine was added in culture medium, and culture medium without addition was used as control. Af-ter cultured for 0, 2, 4, 8, 12, 16 and 24 h, pH and the contents of ammonia nitrogen, bacterial protein and protozoal protein were determined. Animal test, thirty healthy Holstein lactating dairy cows were randomly di-vided into 3 groups, cows in control were fed a basal diet, and those in experimental groups were fed the basal diet supplemented with 13.50 g/( head·d) methionine and 30.00 g/( head·d) rumen protected methionine, respectively. The pretest lasted for 7 days, and the test lasted for 42 days. The results showed as follows:1) in vitro fermentation test, rumen protected methionine had no significant effects on pH, the contents of ammonia nitrogen and bacterial protein of culture medium ( P>0.05) . The protozoal protein content was significantly in-creased by the supplementation of methionine and rumen protected methionine compared with control group ( P<0.05) , but there was no significant difference between the two methionine groups ( P>0.05) . 2) Animal test, no significant differences were detected in the percentages of milk protein and milk fat among groups on the 28th day ( P>0.05) . However, on the 42nd day, rumen protected methionine group was significantly high-er than the other 2 groups in the percentages of milk protein and milk fat ( P<0.05) , and was significantly low-er in serum urea nitrogen and milk urea nitrogen contents ( P<0.05) . Additionally, rumen protected methionine group significantly increased dietary crude protein digestibility compared with the other 2 groups ( P<0.05) . In conclusion, rumen protected methionine has no significant effect on in vitro ruminal fermentation, but can im-prove the percentages of milk protein and milk fat by improving the digestibility of dietary crude protein content of lactating dairy cows.