张一贤老师是宁夏乃至西北兽医界的权威,他从55岁到今年75岁,二十年间把全部精力用在奶牛育种及科学提高奶产量研究上,他与同行们合作育养的奶牛,泌乳期牛奶单产从5000公斤上升到8500公斤……张一贤是宁夏大学农学院退休的教授,他的一些人生故事及他独特的人生价值观, Zhang Yixian is the authority of Ningxia and even the veterinary community in the northwest. From 55 years old to 75 years old this year, he devoted all his energies to dairy breeding and scientific research on milk production in the past 20 years. The cow he co-cultivated with his colleagues and the period of lactation Milk yield rose from 5,000 kg to 8500 kg ... Zhang Yixian is a professor at the Agricultural College of Ningxia University, some of his life stories and his unique values ​​of life,