半胱胺和酵母培养物添加量对奶牛产奶性能及氮排泄的影响

Effects of Supplemental Levels of Cysteamine and Yeast Culture on Milk Performance and Nitrogen Excretion of Dairy Cows

本试验旨在研究半胱胺(cysteamine,CS)和酵母培养物(yeast culture,YC)添加量对奶牛产奶性能及氮排泄的影响。选取年龄、体重、产奶量及泌乳期[(135±15)d]相近的荷斯坦奶牛40头,分为10组。C组饲喂基础饲粮,试验组补饲不同水平组合的CS和YC,其中CS设3个添加量,分别为17.5(L)、20.0(M)和22.5g/(d·头)(H);YC设3个添加量,分别为90(L)、100(M)和110g/(d·头)(H),共9个不同添加量组合,分别为LL、ML、HL、LM、MM、HM、LH、MH和HH组,每组4个重复,每个重复1头。预试期15d,正试期60d。结果表明:1)各试验组产奶量均高于C组,以HM组最高,极显著高于C组(P<0.01);2)各试验组乳脂率、乳蛋白率均高于C组,均以HM组最高,乳中体细胞数则低于C组,以HM组最低,HM组与C组差异均极显著(P<0.01);3)各试验组饲粮氮泌乳转化效率均高于C组,以HM组最高,与C组差异极显著(P<0.01),LL、ML、HL、LM、MM、HM、LH、MH和HH组总氮排泄量比C组分别降低5.23%、8.50%、12.36%、21.92%、24.34%、27.25%、16.31%、18.10%、20.43%,HM组与C组差异极显著(P<0.01)。结果提示,泌乳奶牛饲粮联合添加CS和YC可提高产奶量,改善乳品质,提高饲粮氮泌乳转化效率,降低粪尿氮排泄量;本试验条件下的最佳联合添加组合为CS22.5g/(d·头)、YC 100g/(d·头)。

This experiment was conducted to determine the effects of supplemental levels of cysteamine（CS）and yeast culture（YC）on milk performance and nitrogen excretion of dairy cows.Forty Holstein lactating cows with similar age,body weight,milk yield and lactation stage[（135±15）days in milk]were divided into 10 groups,group C was fed a basal diet,experimental groups were jointly supplemented with CS and YC at different levels.The supplemental levels of CS were designed as 17.5（L）,20.0（M）,22.5g/（d·cow）（H）.The supplemental levels of YC were designed as 90（L）,100（M）,110g/（d·cow）（H）.The experimental groups were LL,ML,HL,LM,MM,HM,LH,MH and HH groups,and each group had 4replicates with 1cow per replicate.The pretest lasted for 15 days,and the test lasted for 60 days.The results showed as follows：1）cows in test groups had greater milk yield than those in group C,specially in group HM,and the difference between groups HM and C was significant（P〈0.01）;2）cows in test groups had greater milk fat percentage and milk protein percentage,but had lower milk somatic cell count,specially in group HM,and the differences between groups HM and C were significant（P〈0.01）;3）compared with group C,dietary nitrogen conversion efficiency of lactation in test groups was increased,specially in group HM,and the difference between groups HM and C was significant（P〈0.01）,and total nitrogen excretion in groups LL,ML,HL,LM,MM,HM,LH,MH and HH was reduced by 5.23%,8.50%,12.36%,21.92%,24.34%,27.25%,16.31%,18.10% and 20.43%,respectively,and the difference between groups HM and C was significant（P〈0.01）.The experimental results indicate that the supplementation of CS and YC in dairy cow diets can greater milk yield,improve milk quality,improve dietary nitrogen conversion efficiency of lactation,and reduce nitrogen excretion;the optimal combination supplemental levels of CS and YC are 22.5and 100g/（d·cow）under the condition in the present study.