| Dairy ketosis is a metabolic disease caused by metabolic disorders of dairy cows resulting in negative energy balance.It occurs mostly in high-yield dairy cows in the late perinatal period.Its main biochemical characteristics are hypoglycemia,high blood ketone and high free fatty acids.At the same time,ketosis has caused great harm to the lactation performance,reproductive performance and postpartum recovery ability of dairy cows,so that the modern large-scale dairy farming industry has suffered huge economic losses.Since the induction of ketosis in dairy cows is closely related to many factors,this topic adopts the method of epidemiological investigation to study the inducement factors and rules of ketosis in pasture and makes corresponding prevention measures in combination with feeding tests,so as to provide technical guidance for the prevention of ketosis in large-scale pasture.By collecting feeding and management data of 12 large-scale ranches in 7 different regions(Northeast China,East China,Central China,Northwest China,North China,North China and Southwest China)in 2021,this study analyzed the incidence of different types of ketosis in ranches and their effects on the incidence of ketosis by season,region,postpartum time,body condition score,parity and yield per unit.The results showed that:(1)the incidence rate of middle clinical ketosis was still large in the modern large-scale pasture,accounting for 36.46%and 5.12%;(2)The incidence of ketosis in summer was the highest,reaching 53.08%,followed by winter,spring and autumn,and the incidence of ketosis in spring and autumn was roughly the same.(3)The incidence of ketosis in southwest China was significantly higher than that in other 6 regions,reaching 44.86%,followed by North China,North China,Northwest China,Central China,East China and Northeast China.(4)The second week after delivery was the high incidence period of cow ketosis,the incidence reached 6.44%,and then the incidence decreased.(5)From the perspective of individual cows,body condition score of3.25,parities of the third parities,and yield of 12000 Kg/ head were critical values.When the above values exceeded the critical values,the incidence of ketosis of cows increased significantly,and the incidence of ketosis subsequently increased.The effects of different health care agents on the prevention of ketosis of dairy cows,the effects on feed intake and single dose of postpartum dairy cows and the economic benefits of different health care agents were compared by feeding test.The results showed as follows:(1)Compared with other groups,the incidence of ketosis in the experimental group treated with rumen choline was lower(2.63%);(2)Both rumen choline and B vitamins had significant effects on the recovery of postpartum dry matter intake(P < 0.01).(3)Compared with the control group,both B vitamins and choline over rumen had certain effects on unit yield,and the effect of B vitamins was better than that of choline over rumen(P < 0.01).(4)As for the economic benefits,the cost of B vitamins is slightly higher than that of rumen choline;the economic benefits generated by B vitamins are much higher than that of rumen choline.In conclusion,the following guidelines are given for the prevention measures of ketosis in large-scale pastures:(1)Based on the location of pastures,the areas with high ambient temperature and humidity throughout the year,the rumen choline should be used as the main health care agent.(2)According to the herd structure,the diets of dairy cows with parity greater than 3,yield greater than 12000 Kg and body condition score greater than 3.75 were mainly supplemented with rumen choline,which not only ensured the healthy and stable yield of dairy cows,but also prevented the occurrence of subclinical ketoosis.The diet of cows with parity less than 3,yield less than 12000 Kg and body condition score less than 3.75 is mainly supplemented with B vitamins,which can not only ensure the health of cows,but also effectively improve the yield of cows.(3)According to the incidence: monitoring and early warning of ketosis in pasture should be carried out every month.When the incidence of ketosis was more than 3%,choline was used as the main health care agent.When the incidence of ketosis was less than 3%,B vitamins were used as the main health care agent.(4)Rumen choline was used to prevent ketosis during the whole perinatal period.i.e.,21 days before and 21 days after delivery,and B vitamins were used from the 22 nd day after delivery,so to achieve the purpose of increasing yield and improving economic benefits. |
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