Comprehensive Analysis Of Production Performance Of Dairy Cattle In Shaanxi Dairy Farms By Using DHI

Cow performance measurement is an effective means of monitoring the milk production level and health status of dairy cows.The purpose of this study was to analyze the effect of the performance measurement of dairy farms in Shaanxi Province,and to study the correlation of related indicators(somatic cell count,parity,milk yield,milk composition).A total of 19,729 cows were surveyed in 62 cattle farms in Shaanxi Province from January to December 2018,and 113,842 DHI records and milk analysis for each cow were investigated.Get the following results:1.The changes in daily milk production in different scales of dairy farms of various scales show a certain regular fluctuation.Milk production decreased at the end of the spring to summer.At the end of summer or during the fall,milk production begins to rise.The average annual milk production of the 2100-2899 dairy farms reached 26.70 kg,Higher than other dairy farms;The 90-299 head farm is the lowest.The somatic cell count increased first and then decreased.The milk protein rate gradually increased from 2.90% to 3.60% from January to April,and then gradually decreased after 3.60%.It began to rise again after August.The milk fat percentage of dairy farms of all sizes increased first and then decreased and then gradually increased.2.The higher the somatic cell count in dairy cows,the lower the milk yield,Especially when the somatic cell count exceeds 500,000/mL,the milk yield is especially reduced.The higher the parity,the higher the number of somatic cells.3.With the increase of milk somatic cell count,the milk fat percentage has a downward trend,but the difference is not significant.When the somatic cell count does not exceed 500,000/ml,the milk fat percentage increases with the increase of somatic cell count.However,when the somatic cell count exceeds 500,000/mL,the milk fat percentage decreases as the number of somatic cells increases;Somatic cell counts were inversely correlated with lactose content.4.The order of milk yield of different parity is from high to low: 2 births > 3 births > 1 birth;the milk fat percentage and milk protein rate of 1 fetal cow are significantly lower than 2 fetal cattle and 3 fetal cattle.The parity has a significant effect on the lactose content of milk.As the parity increases,the lactose content decreases.5.The milk protein rate was significantly lower than that of other lactation days at 60 days before lactation.With the delay of lactation days,the milk protein rate gradually increased.The milk fat percentage was higher than that of other lactation days in the first 60 days of lactation,and the milk fat percentage was significantly lower than that of other lactation days group at 251-305 d and >305 d.During the whole lactation period,the milk fat percentage has a tendency to decline first and then rise and then fall again.The milk urea nitrogen was lower than other lactation days in the first 30 days,and the milk urea nitrogen decreased with the change of lactation days.There was no significant change in lactose content throughout the lactation period,The somatic cell count decreased first and then increased with the change of lactation days.