饲用甜高粱青贮替代玉米青贮对泌乳中后期奶牛产奶性能的影响

Effects of Substitution of Forage Sorghum Silage for Corn Silage on Milk Performance of Dairy Cows in Middle and Late Lactation

试验旨在研究饲用甜高粱青贮替代玉米青贮对泌乳中后期荷斯坦奶牛产奶性能的影响。选取体重、年龄及泌乳期相近的40头健康荷斯坦泌乳中后期奶牛,随机分为2组,分别为对照组和试验组,每组20头,隔栏单独饲养。对照组饲喂含有玉米青贮的青贮混合饲料、试验组饲喂含有饲用甜高粱青贮的青贮混合饲料,进行70d的饲养试验,其中预饲期10d,正饲期60d。结果显示,在整个试验期两组奶牛日均产奶量逐渐降低,试验组平均为16.48±3.92kg/d,对照组平均为16.37±4.66kg/d,试验组高于对照组,差异不显著(P>0.05);随着试验天数的增加,试验组与对照组相比乳脂率、乳蛋白率、乳糖率、总固形物、非脂固形物升高,冰点和乳尿素氮降低,试验组与对照组乳成分差异不显著(P>0.05),其中0~60d试验组乳蛋白率和乳尿素氮含量有高于对照组的趋势,试验组乳蛋白率和乳尿素氮含量分别为3.60%、16.88mg/100mL。本试验在泌乳中后期奶牛中使用饲用甜高粱青贮替代玉米青贮后产奶量及乳成分结果接近。因此,在本试验条件下,使用饲用甜高粱青贮代替玉米青贮饲喂泌乳中后期荷斯坦奶牛是可行的。

The experiment was conducted to study the effects of substituting forage sorghum silage for corn silage on milk performance of dairy cows in middle and late lactation.Forty healthy Holstein cows in middle and late lactation with same weight,age and milk yield were randomly divided into 2 groups（control group and experimental group）and 20 cows in each group,feeding separately.Cows in control group were fed with the mixed feed containing corn silage,those in the experimental group were fed with the mixed feed containing forage sorghum silage.The experiment lasted for 70 days comprised a 10 dadaptation and 60 dtrial period.The results showed that the average daily milk yield of both groups were decreased gradually,the average daily milk yield of the experimental group and the control group were 16.48±3.92,16.37±4.66kg/day,respectively,which was higher in the experimental group than the control group,but with no significant difference（P〈0.05）.As the experiment went on,the milk fat percentage,milk protein percentage,lactose,total solids,and non-fat solids were increased,while the freezing point and urea nitrogen of milk in the experimental group were decreased compared with the control group.There was no significant difference in milk composition between the experimental group and the control group（P〈0.05）.The milk protein content and milk urea nitrogen content in the 0~60 dexperimental group had a tendency to be higher than those in the control group.The milk protein rate and urea nitrogen content of the experimental group were 3.60% and 16.88mg/100 ml,respectively.The milk yield and milk composition of cows in middle and late lactation that were fed with forage sorghum silage instead of corn silage were close.Therefore,it is feasible to substitute forage sorghum silage for corn silage in the diet of dairy cows.