Milk Urea Nitrogen is one of the routine test indicators in the determination of Dairy Herd Improvement.Its concentration is usually used to monitor the nutritional status of dairy cows and reflect the energy nitrogen balance,reproductive performance and nitrogen emission in the environment.MUN concentration varies by individual and dietary composition,and is influenced by a number of factors.Accurate estimation of MUN genetic parameters can not only improve the economic benefits of cattle farms,but also accelerate the genetic progress of dairy cow,providing a theoretical basis for breeding high-quality dairy cow.In this paper,the factors in influencing MUN at home and abroad,the heritability,and the genetic correlation with milk composition indexes such as milk fat percentage,milk protein percentage,lactose percentage,milk yield,somatic cell score and other yield and health traits were reviewed,in order to provide references for the further study and application of MUN.
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