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随着人民生活水平的提高,人们对鲜奶和奶制品的需求量不断增长。在发展奶牛业的过程中,一方面要提高繁殖率,增加泌乳牛头数;另一方面要不断提高头日产奶量、泌乳期产奶量和终身产奶量。中国黑白花奶牛产奶量高,但不耐热,在热带、亚热带和南温带地区夏季,因热应激影响,热平衡失调,
As people’s living standards improve, people’s demand for milk and dairy products continues to grow. In the process of developing the dairy industry, on the one hand, it is necessary to increase the breeding rate and increase the number of lactating bullheads; on the other hand, it is necessary to continuously improve the first day milk yield, lactation milk yield and lifelong milk yield. Chinese Holstein dairy cows have high milk yield, but are not heat-tolerant. In the tropical regions of the tropics, subtropics and the southern temperate regions, due to heat stress, heat balance disorders,