玉米粉碎粒度对产后奶牛瘤胃发酵及生产性能的影响

Study on effects of granularity size of corn in diet on rumen fermentation, production performance in lactating dairy cows

旨在研究玉米粉碎粒度对泌乳早期奶牛瘤胃发酵、产奶量及乳成分的影响。试验选择4头泌乳天数为14 d,日产奶量25 kg左右,体重550 kg左右的经产(二胎)中国荷斯坦泌乳奶牛,随机分为两组,对照组奶牛日粮添加10%的破碎玉米,将对该比例破碎玉米由细粉碎玉米代替,作为试验组。试验采用2×2交叉试验设计,每期21 d。结果表明:试验组奶牛瘤胃液pH值显著低于对照组(P<0.05);与对照组相比,试验组奶牛瘤胃液乙酸、丙酸与对照组相比有所增加,乙丙比例降低,丁酸具有增高的趋势,与对照组相比提高了17.77%,但差异均不显著(P>0.05)。试验组奶牛瘤胃液微生物蛋白与对照组比较有增加的趋势,合成效率与对照组比较无显著性差异(P>0.05);试验组奶牛瘤胃液氨态氮的含量显著低于对照组(P<0.05)。试验组奶牛产奶量高于对照组,乳脂率与对照组相比有所降低,但差异均不显著(P>0.05);随着玉米粉碎粒度的降低,奶牛乳中乳蛋白率有增高趋势,与对照组相比提高了7%;试验组奶牛乳中尿素氮显著低于对照组(P<0.05)。说明在本试验条件下,细粉碎玉米替代日粮中部分破碎玉米,可以提高奶牛瘤胃的发酵功能,使奶牛乳中乳蛋白率有增高趋势。

The aim of this study was to study the effects of granularity size of corn in diet on ruminal fermentation, production performance in early lactating cows. Four healthy Chinese Holstein lactating dairy cows were selected with the same parity, similar lactation period of lactation stage, and were randomly divided into two groups. In the control group, 10% of the broken com was added to the diet, and the crushed com was replaced by fine crushed com as the test group, using a 2x2 crossover design,21 days per phase.The results showed that pH value of the rumen in the experimental group was significantly lower than that of the control group （P〈0.05）. Compared with the control group, the acetic acid and propionic acid of the gastric juice of the cows in the experimental group were increased, the proportion of EPDM was lower, the butyric acid was increased, and the difference was 17.77%, but the difference was not significant （P〉0.05）. There was an increasing trend in the rumen microbial protein in the experimental group compared with the control group, and there was no significant difference in the synthetic efficiency compared with the control group （P〉0.05）, and the content of ammonia nitrogen in the rumen of the experimental group was significantly lower than that of the control group （P〈0.05）. The milk yield of the test group was higher than that of the control group, the milk fat rate was lower than the control group, but the difference was not significant （P〉0.05）. With the decrease of the grain size of the corn, the milk protein rate of milk cow increased by 7%, compared with the control group, the urine nitrogen in the milk of the test group was significantly lower than that of the control group （P〈0.05）.