Investigation Of Production And Reproduction Of Dairy Cows In Large Dairy Farms In Yinchuan, Ningxia

In order to know the milk performance and reproduction performance of dairy cows in Yinchuan region, the investigation of milk performances and reproduction performances of dairy cows in Yinchuan region were conducted, and the concentrations of serum copper, zinc, manganese of dairy cows were measured.The results showed that:during 2011～2014, the average daily milk yields and 305 day milk yields were raised year by year (P<0.05); the milk fat rates and the milk protein rate had changed obviously (P<0.05); the contents of milk urea nitrogen were apropriate; somatic cell count(SCC)reduced signifcentlly year by year (P<0.01); the milk yields in summer had higher than other seasons (P<0.01); the milk fat percentages and the milk protein percentages in winter were highest, while those in winter were lowest (P<0.01); the milk urea nitrogen contents were higher than other seasons; SCC in winter were highest, and SCC in February were obviously higher than other months (P<0.05); the daily milk yields and 305 day milk yields were raised(P<0.05) with the increase of parity, and were decreased after 4 parity; the milk fat percentages and the milk protein percentages were reduced gradually from lto3 parity and rised slowly after 4 parity; SCC were enhanced with the increase of parity, and SCC were significantly raised from 1 parity to 3 parity (P<0.01).During 2011～2014, the oestrus fecundation rates of dairy cows were 42.73%～46.68%, the oestrus fecundation rate in 2012 was highest and higher than that in 2011 (P<0.05); the first estrus conception rates were 39.53%～48.04%, the first estrus conception rate in 2013 was highest and higher than that in 2012(P<0.05); the calving intervals were 426.38～433.39 day, there was no sifnificant difference among years (P>0.05); the rates of placental retention were 18.14%～23.26%, and that in 2012 was significantly lower than other years (P<0.05); the abortion rates were 9.87%～13.41%, and that in 2014 was lower than other years (P<0.05).Daily milk yield and milk protein percentage, milk urea nitrogen content, SCC showed significant negative correlation (P<0.01); SCC and milk fat percentage was significantly negatively correlation (P<0.01), was positively correlated with milk urea nitrogen (P<0.05); milk fat percentage and milk urea nitrogenwas negative correlation (P<0.05), and significantly positive correlation with the milk protein percentage(P<0.01).The serum concentrations of copper, zinc of dairy cows which were not easy pregnant were higher than those of diary cows which were easy pregnant, the serum concentrations of manganese of diary cows had no difference.The results of study showed that the milk performance of dairy cows in Yinchuan region were high, but management of reproduction need to improve in order to enhance the conception rate, short calving interval and prevent occurrence of reproductive diseases; the serum concentrations of copper, zinc, manganese of easy and not easy pregnant cows had no difference, suggested that which may not be the factors affecting the reproductive performance of dairy cows in Yinchuan area.