Effects Of Intensive On-farm Body Condition Management On Metabolism, Performance And Health Of Lactating Dairy Cows

Body condition is a reflection of nutrient reserve level of dairy cows.Improper body condition management has adverse effects on production performance and health of dairy cows and will bring great economic losses to dairy industry.Although there are existing body condition management goals for dairy cow lactation cycle at home and abroad,there are inconsistent standards,insufficient attention in intensive cattle farms,and different control effects.Therefore,this study evaluated the effects of body condition management of dairy cows in intensive dairy farms through two experiments,“Investigation on body condition,performance and health of dairy cows in lactation cycle in four intensive dairy farms” and “Effects of body condition loss of dairy cows during perinatal period on metabolism,performance,health and economic benefits”.It lays a foundation for the effective standard technology or standard for the optimization management of the body condition of dairy cows in intensive cattle farms.1.Investigation on body condition,production performance and health of dairy cows in four intensive dairy farms during lactation cycle.This experiment was conducted in four large intensive dairy farms in Heilongjiang Province.A total of 2276 cows were randomly selected from 7 time points,including prepartum 21 days,the day of calving,21 days,50 days,150 days,200 days and 250 days after calving.BCS,milk yield,production performance,disease and economic benefits of experimental cows were recorded in detail.At the same time,according to BCS,cows were divided into 7 groups: BCS ≤ 2.5,BCS = 2.75,BCS = 3,BCS = 3.25,BCS =3.5,BCS = 3.75 and BCS ≥ 4.Each group had 40 heads at each time point.One way ANOVA,descriptive statistics and chi square test were used to analyze all data from the different farms or groups.The results showed below:(1)Four intensive dairy farms in Heilongjiang Province have different body condition management levels,which does not meet the standards of body condition management at home and abroad.The order of BCS management level of lactating cows in dairy farms was farm D,B,C and A from high to low.(2)There were significant differences in daily milk production,disease incidence and times,or death rate and reproductive performances among four intensive dairy farms in Heilongjiang Province(P < 0.05).Among them,The order of lactation performance from excellent to inferior was farm D,farm C,farm B and farm A.The order of disease and reproduction management from excellent to inferior was farm B,farm D,farm A,farm C.(3)The order of net profit of lactating cows in four farms from excellent to inferior was farm D,farm B,farm C and farm A.The best BCS of 21 days before delivery and delivery day was 3.5;the best BCS of 21 days after delivery was 3.25;the best BCS of 50 days to 250 days after delivery was 3.5.2.Effects of perinatal body condition loss on metabolism,performance,health and economic benefits of dairy cows.In a large intensive dairy farm in Heilongjiang Province,156 cows were randomly selected for prospective observation.According to the degree of perinatal body condition loss,cows were divided into three groups: no body condition loss group(group M,BCS loss 0);low body condition loss group(group L,BCS loss 0.25);high body condition loss group(Group H,BCS loss ≥ 0.5).Blood samples were collected on prepartum 21 days,the day of calving,7 days,14 days,21 days,28 days and 50 days after calving.The milk yield,production performance,disease and economic benefits of dairy cows were recorded in detail.GLM model analysis,one-way ANOVA,descriptive statistics,chi square test,Pearman correlation analysis,binary logistic regression model analysis and receiver operating characteristic curve(ROC)prediction were used to analyze all data from the different groups.The results showed below:(1)BCS 21 days before delivery had a good early warning effect on BCS loss in late perinatal period.The early warning values of BCS at 21 days before delivery were 3.375,3.625 and 3.875 respectively when the BCS loss was more than 0,0.25 and 0.5 in late perinatal period.(2)High BCS in early perinatal period and high BCS loss in late perinatal period lead to negative energy balance(BHBA,NEFA,LP increased,Glu,INS decreased),abnormal liver function(AST,ALB,TC increased),oxidative stress(T-AOC decreased,MDA increased),decreased daily milk production and reproductive performance,and increased disease incidence.(3)The degree of BCS loss in late perinatal period has a certain diagnostic value for ketosis and abomasal displacement,but has a low diagnostic value for endometritis.The early warning values of perinatal BCS loss of ketosis,abomasal displacement and endometritis were 0.375,0.625 and 0.375,respectively.(4)The daily net profit of dairy cows in group L was the highest,followed by group M and group H was the lowest.The economic benefit is better when the body condition loss is controlled at 0.25 in the late perinatal period.Once the body condition loss exceeds 0.50,postpartum metabolism,production performance,health and economic benefits of dairy cows will be adversely affected.Conclusion: According to the comprehensive evaluation of production performance,health and economic benefit of four intensive cattle farms in Heilongjiang Province,the management level of cattle farm D is the best,followed by cattle farm B,followed by cattle farm C and A.The control objectives of body condition management for lactating cows were determined.It was identified that perinatal BCS and its loss were important risk factors for the decline of performance,health and economic benefits in dairy cows.The early warning effect of 21 day prenatal BCS on the degree of perinatal BCS loss in dairy cows was established,and the diagnostic value of BCS loss on ketosis,abomasum displacement and metritis was established.