Study On The Relationship Between The Early Peripartum Days And Gestational Days,Calves Birth Weight And Postpartum Metabolic Diseases In Dairy Cows

The peripartum days of dairy cows can be divided into two periods:the early peripartum days and the late peripartum days.Based on the theory of"mother child integration",the nutrition strategy and feeding management in the early peripartum days are crucial.The length of the early peripartum days directly affects the postpartum health,lactation performance and reproductive performance of cows,and also directly affects the birth weight and health of calves.In production practice,the period of cows stayed in the enclosure in the early peripartum days was named the early peripartum days,commonly known as"peripartum days".In actual production,the early peripartum days were determined according to the actually gestational days of cows so as to adjust the herd.The Length of early peripartum days has a significant impact on the gestational days,the birth weight of calves,and the occurrence of postpartum metabolic diseases of dairy cows.This experiment collected the production data of large-scale pastures in Ningxia,Hebei and Gansu regions with similar nutritional level and feeding management level.The data of dairy cattle and calves with gestational days greater than or equal to 260 days and less than 297 days,peripartum days of 1-45 days,and calves birth weight greater than 25 kg were selected for statistical analysis.This experiment aimed to explore the relationship between peripartum days and gestational days,calves birth weight and postpartum metabolic disease,and finds the appropriate range of the peripartum days.At the same time,through the research on the relationship between in the early peripartum period days and the gestational days to provide a preliminary theoretical basis for the days of herd adjustment in the early perinatal period,better guide production,and improve the economic benefits of the pasture.The research results are as follows:Study I:Correlation analysis between the early peripartum day,gestational days,birth weight of calves and postpartum metabolic disease of dairy cowsThis study analyzed the data of peripartum day,gestational days,birth weight and postpartum metabolic disease of dairy calves in Ningxia,Hebei and Gansu.The results showed that with the increase of the days in the early peripartum day and the of gestational days,the birth weight of calves also increased.The birth weight of calves produced by primiparity and multiparity cows in the three regions was mainly 35-45 kg.The birth weight of male calves in all regions were higher than that of female calves(P<0.05).And the birth weight of calves born to multiparous cows were higher than that of calves born to primiparity cows,and the difference was significant(P<0.05).The birth weight of calves,the early peripartum day and gestational days in Hebei were the largest,and the difference was significant(P<0.05).The study found that in Ningxia,Gansu and Hebei,the incidence of persistent placenta decreased with the increase of peripartum days of cows,and the incidence of persistent placenta was the highest when the peripartum days were less than 15 days.However,the incidence of postpartum paralysis increased with the increase of perinatal days.Although the correlation between the two metabolic diseases and the peripartum days is opposite,the turning point occurs at 21 days.Study 2:Correlation analysis between the early peripartum day and gestational daysOn the basis of study one,this study further analyzed the relationship between the early peripartum day and gestational days in Ningxia,Hebei and Gansu.The difference between the early actual peripartum days of cows and the early theoretical peripartum days is set as x,and the gestational days of cows are set as y.The regression equation between x and y is established.It is found that the regression equation R~2 is greater than 0.7,indicating that the two have a strong correlation.The coefficient of the equation showed that the gestational days increases with increase of the early peripartum days.According to Pearson correlation analysis,the gestational days and the early peripartum days of cows were significantly positively correlated(R~2>0.65,P<0.01),gestational days and the early peripartum days of cows were also significantly positively correlated with calves birth weight(P<0.01),separately.Conclusion:According to the correlation analysis between the early peripartum days,gestational days,calf birth weight and postpartum metabolic diseases,the reasonable early peripartum days is 15-21 days.According to the positive correlation between the difference of the actual early peripartum days and theoretical early peripartum days and the gestational days,with the early peripartum days increased,the gestational days increased.Therefore,in order to keep the early peripartum days most cattle between 15-21 days,it is recommended to adjust the herd at least twice a week.