荷斯坦牛冻精改良西藏黄牛的泌乳性能分析

目的]西藏拉萨市引进荷斯坦牛冻精与本地黄牛级进杂交已40余年，对荷斯坦牛改良西藏黄牛（荷×藏）级进杂交后代泌乳性能进行测定，为后期横交固定育种工作提供基础数据和科学依据。方法]统计并比较2017—2021年荷×藏高代次不同胎次之间的总泌乳量、高峰产奶量、高峰日、产奶天数和日泌乳量；2021年7月进行奶牛生产性能测定（DHI）。结果]荷×藏高代次随着胎次增加总泌乳量、高峰产奶量、泌乳天数和日泌乳量随之降低，高峰泌乳日在正常范围内；3个胎次之间，总泌乳量主要集中在2000 ~ 4000 kg，高峰产奶量主要集中在15 kg ~ 25 kg，高峰日、产奶天数和日泌乳量的范围分别是49.58 d ~ 66.30 d、212.06 d ~ 217.36 d和14.96 kg ~ 17.99 kg。DHI测定数据显示荷×藏高代次群体乳脂率、乳蛋白率和尿素氮分别是3.86 %、3.34 %和12.47 mg/dL。结论]高原低氧环境限制限制了荷×藏高代次牛的泌乳性能，但相比西藏黄牛有较大提高，结果可作为提高改良牛生产性能、产奶量、奶品质及遗传特性提供基础数据。

Analysis of lactation performance of Tibetan yellow cattle improved by Holstein frozen semen

Objective] it has been more than 40 years since the introduction of frozen semen from Holstein cattle in Lhasa City, Tibet, and the lactation performance of the offspring of the improved Tibetan yellow cattle has been measured, so as to provide basic data and scientific basis for the later cross fixed breeding. Methods] the total milk production, peak milk production, peak days, days of milk production and daily milk production were counted and compared between 2017 and 2021; In July, 2021, dairy cow production performance test (DHI) was conducted. results] the total lactation, peak milk yield, lactation days and daily lactation decreased with the increase of parity, and the peak lactation days were within the normal range; Among the three parity, the total milk production was mainly concentrated in 2000 ~ 4000 kg, the peak milk production was mainly concentrated in 15 ~ 25 kg, and the range of peak days, milk production days and daily milk production were 49.58 ~ 66.30 days, 212.06 ~ 217.36 days and 14.96 ~ 17.99 kg respectively. The DHI data showed that the milk fat rate, milk protein rate and urea nitrogen of the high generation population were 3.86%, 3.34% and 12.47 mg/dl respectively. Conclusion] the high altitude hypoxia environment limits the lactation performance of high generation cattle, but it is significantly higher than that of Tibetan yellow cattle. The results can provide basic data for improving the production performance, milk yield, milk quality and genetic characteristics of improved cattle.