Effect Of MUN,Ratio Of Fat And Protein Percentage On Milking Performances And Diseases Of Cows In Early Lactation

Milk urea nitrogen(MUN)an important detection index in dairy herd improvement plan(DHI),which can not only reflect the dietary protein level,nitrogen balance,nitrogen excretion prediction,but also evaluate reproductive performance and production performance of cows,At the same time,has a certain relationship with nutritional and metabolic diseases of dairy cows.Milk fat-to-protein ratio(FPR)is the ratio of fat and protein in milk.The milk yield,milk fat content and milk protein content are the main indicator of the lactation performances,which are the main indicator of the lactation performance the key to the large-scale dairy farm to obtain high efficiency.To explore the effects of the MUN and FPR on milking performances and diseases of cows in early lactation,the data of 4 4750 DHI test day records for 3729Chinese Holstein from the large dairy farm of Jiangsu in Dec.,2014to Nov.,2015 was selected in this study.was selected in this study.The effects of different years,months,parity,calving season,lactation month on MUN content and FRP were analyzed by multivariate analysis of variance(ANOVA).Meanwhile,This study was conducted on 1552 dairy cows in a large dairy farm of Jiangsu in Dec.,2014to Feb.,2015.The milk sample was collected from all cows in 30 days’postpartum and the MUN,FPR and daily milk performances in the milk were measured.The cattle with 150 days postpartum abortion,abomasum displacement,mastitis,metritis incidence of hoof and leg disease were collected.Then,the relationships of MUN content and FPR in milk with postpartum lactation performance and disease were analyzed by ANOVA,and Logistic regression.These results could improve the production performance and reduce the incidence of postpartum diseases of Chinese Holstein cows,and provide scientific basis for improving the economic benefits of dairy farming.The main results are as follows:The MUN content was affected extremely significantly by different seasons,calving seasons,lactating months and parities(P<0.01).MUN content in the fifth determination month was significantly higher than other seasons.The MUN content of dairy cow calving in winter was significantly higher than the cows calving in other seasons,while the MUN content of cows calving in spring were the lowest.With the increase of parity,the MUN content showed an increasing tendency.The MUN content was significantly higher in the ninth lactation month and an the minimum MUN content was observed in the first lactation month.The MUN showed a positive correlation with daily milk yield、fat percentage,Lactose and total solid in milk(P<0.01),and negative correlation with SCC、Milk protein percentage,and SCS content(P<0.01).The FPR content was affected extremely significantly by different seasons,calving seasons,lactating months and parities(P<0.01).The FPR in the first determination month is the highest,and it drops sharply from 2th to 9th of lactation month.The FPR in the first lactation is the highest and the minimum FPR was observed in the twelth lactation month.The FPR in the first parity is significantly lower than the other parities.The FPR showed a positive correlation with daily milk yield、fat percentage,lactose and total solid in milk(P<0.01),and negative correlation with protein percentage and lactose content(P<0.01).Animals with a low FPR(<1.00)in early lactation have a lower daily milk yield,fat percentage and total solid in milk,and also have a higher SCC and protein percentage.Animals with a high MUN(>15.00 mg/dL)have a higher fat percentage,protein percentage,SCC and total solid,and have a lower lactose content(P<0.05).MUN has a significant effect on abomasum displacement in 150 days’ postpartum.In the same time,a highly significant effect on the incidence of feet diseases and abomasum displacement was observed(P<0.05).The early lactation MUN and FPR were the prognostic values on daily milking performance and the incidence of diseases.