半胱胺和过瘤胃蛋氨酸不同组合对奶牛产奶性能、瘤胃微生物蛋白产量和氮排泄的影响

Effects of Different Combinations of Cysteamine and Rumen⁃Protected Methionine on Lactation Performance,Rumen Microbial Protein Production and Nitrogen Excretion of Dairy Cows

本试验旨在研究半胱胺(CS)和过瘤胃蛋氨酸(RPMet)不同组合对奶牛产奶性能、瘤胃微生物蛋白(MCP)产量和氮排泄的影响。选取年龄、体重、胎次、产奶量、乳成分及泌乳天数相近的荷斯坦奶牛40头,随机分为10组,每组4头。对照(C)组饲喂基础饲粮,试验组添加不同水平的CS和RPMet。CS添加水平分别为13(L)、15(M)、17 g/(d·头)(H),RPMet添加水平分别为23(L)、25(M)、27 g/(d·头)(H),共组成9个不同组合,分别为LL、LM、LH、ML、MM、MH、HL、HM、HH组(第1个字母为CS添加水平,第2个字母为RPMet添加水平)。预试期15 d,正试期60 d。结果表明:1)在产奶量方面,各试验组均显著或极显著高于C组(P<0.05或P<0.01),其中HL组提高幅度最大,较C组提高了19.76%。2)在乳成分方面,LL、LH、ML、MM、MH、HL、HM、HH组乳脂率极显著高于C组(P<0.01),LH、HL、HH组乳蛋白率极显著高于C组(P<0.01),ML、HH组乳体细胞数极显著低于C组(P<0.01)。3)在瘤胃MCP产量方面,HL组极显著高于C组(P<0.01)。4)在氮总排泄量方面,各试验组均极显著低于C组(P<0.01);在氮表观消化率方面,各试验组均极显著高于C组(P<0.01)。综合考虑上述指标,以17 g/(d·头)CS+23 g/(d·头)RPMet为最佳组合。

This experiment was conducted to determine the effects of different combinations of cysteamine(CS)and rumen⁃protected methionine(RPMet)on lactation performance,rumen microbial protein(MCP)production and nitrogen excretion of dairy cows.Forty Holstein lactating cows with similar age,body weight,parity,milk yield,milk composition and lactation days were selected and randomly divided into 10 groups with 4 cows in each group.Cows in the control group(C)was fed a basic diet,and cows in experimental groups was supplemented with different combinations of CS and RPMet.The supplemental levels of CS were 13(L),15(M)and 17(H)g/(d·head),respectively;and the supplemental levels of RPMet were 23(L),25(M),27(H)g/(d·head),respectively.A total of 9 experimental groups were designed,which were named as LL,LM,LH,ML,MM,MH,HL,HM and HH groups(first letter indicated CS supplemental level,and the second letter indicated RPMet supplemental level),respectively.The pre⁃experiment lasted for 15 days,and the experiment lasted for 60 days.The results showed as follows:1)in terms of the milk yield,all experimental groups were significantly higher than the C group(P<0.05 or P<0.01),the HL group had the largest increase range,which was 19.76%higher than the C group.2)In terms of the milk composition,the milk fat rate of LL,LH,ML,MM,MH,HL,HM and HH groups was significantly higher than that of the C group(P<0.01),the milk protein rate of LH,HL and HH groups was significantly higher than that of the C group(P<0.01),and the milk somatic cell count of ML and HH groups was significantly lower than that of the C group(P<0.01).3)In terms of the rumen MCP production,the HL group was significantly higher than the C group(P<0.01).4)In terms of the total nitrogen excretion,all experimental groups were significantly lower than the C group(P<0.01);in terms of the apparent digestibility of nitrogen,all experimental groups were significantly higher than the C group(P<0.01).In combination with various test indicators,the 17 g/(d·head)CS+23 g/(d·head)RPMet is the best combination.