摘　要：本试验研究了在饲料中添加活性酵母及培养物对不同泌乳期荷斯坦奶牛泌乳性能、采食量、血液生化指标及免疫力的影响。试验采用两因素完全随机区组试验设计，根据体重、胎次相近原则，将48头体重为（534±20）kg的泌乳期奶牛分为4组，每组12头，其中泌乳前期6头，泌乳中期6头。对照组（CG组）饲喂基础日粮，另外3个试验组分别在对照组的基础上添加0.075%乐斯福酵母（LY组）、0.100%富硒酵母（SY组）以及0.075%乐斯福酵母和0.100%富硒酵母的混合物（LY+SY组）。试验总周期为45 d，其中包括10 d预饲期和35 d正式期。试验结果表明：1）相比于对照组和其他2个试验组，SY组均显著提高了产奶量（P<0.05）；2）各处理组之间奶牛采食量无显著差异（P>0.05），SY组泌乳初期的饲料利用率显著低于LY组和LY+SY组，而在泌乳中期，不同处理对饲料利用率无显著性影响（P>0.05）；3）泌乳前期，奶牛血液中的淀粉酶（AMY）以CG组中的含量最高，但差异并不显著（P>0.05），而在泌乳中期，LY+SY组奶牛血液中AMY和乳酸脱氢酶（LDH）的含量显著高于其他3个试验组（P<0.05）；泌乳前期，各处理组奶牛血液中的3种免疫球蛋白含量差异不显著（P>0.05），而在泌乳中期，LY+SY组的IgG含量显著高于CG组和SY组（P<0.05）。综上可知，饲料中添加活性酵母和培养物对提高奶牛的免疫力有积极作用。本研究为养殖业中奶牛的饲料配方提供了一定的理论支撑和指导意义。
关键词：活性酵母；酵母培养物；产奶性能；血液生化指标；免疫力

Abstract: The purpose of this experiment was to explore the effects of adding active yeasts and their cultures on the lactation performance, feed intake, blood biochemical parameters and immunity of lactating Holstein cows in different lactation periods. The experiment used a two-factor completely randomized block test design. According to the principle of similar body weight and parity, 48 lactating dairy cows were divided into four groups, 12 in each group, 6 in pre-lactation and 6 in mid-lactation. The cow in the control group (CG group) was fed with the basic diet, and cows in the other three groups were fed with 0.075% LY yeast, 0.100% Se-enriched yeast (SY group) and 0.075% Se-enriched yeast and Lesfox yeast mixture (LY+SY group). The trial period of the study was 45 days, including 10 days of adaptation and 35 days of experiment. The results showed that: 1) Compared with the CG group and the other two experimental groups, the milk yield in SY group was significantly increased (P<0.05). 2) There was no significant difference in feeding intake among the four treatment groups (P>0.05). The feed utilization rate in SY group was significantly lower than that in LY group and LY+SY group at the early lactation stage (P<0.05), whereas there was no significant difference in feed utilization rate between different treatments at the middle lactation stage (P>0.05). 3) The level of blood amylase (AMY) in CG group was the highest at the early lactation stage, whereas the difference was not significant (P>0.05). The level of blood AMY and lactate dehydrogenase (LDH) in LY+SY group were significantly higher than those of other three groups at the middle lactation stage (P<0.05). There were no significant differences in blood immunoglobulins in all groups in the early lactation (P>0.05). However, the IgG content in LY+SY group was significantly higher than those in CG group and SY group in the middle lactation stage (P<0.05). In conclusion, the addition of active yeast and their culture in feed has a positive effect on improving immunity of dairy cows. This study provides a certain theoretical support and guiding significance for the feed formulation of dairy cows in the breeding industry.
Key words: active yeast; yeast culture; milk production performance; blood biochemical indicators; immunity