The Effect and Correlation of Different Lactation Stages and Parity on Lactation Performance of Dairy Cows in Guangdong Province
In this paper,the effects of different lactation stages and parity on the lactation performance of dairy cows,as well as their change rules and correlation were studied by analyzing the Dairy Herd Improvement(DHI)data of a large-scale dairy farm in Guangdong Province in 2022.The results showed that,with the increase of lactation days,the milk yield,urea nitrogen and fat-protein ratio of dairy cows increased first and then decreased,the milk protein rate and milk fat rate decreased first and then increased,while the somatic cell count increased gradually.With the increase of parity,the milk yield,milk fat rate and fat-to-protein ratio of dairy cows showed a trend of increasing first and then decreasing.Milk urea nitrogen increased first,then decreased and then increased,milk protein increased first,then decreased,then increased and then decreased,while somatic cell count increased gradually.Therefore,based on the lactation stage and parity,dairy cows should be reasonably grouped and feed formulated,so as to improve the milk quality and the economic benefits of dairy farms.
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