Study On The Dynamic Changes Of Serum Hormone Indexes In Perinatal Dairy Cows

40prenatal45d cows have been chosen to characterize the endocrine metabolism in perinatal dairy cows, to make more reasonable nutrition regulation, and to improve the anti-stress ability of cows. Their blood collected from the tail vein every5d were used to detect the concentration of serum Prolactin (PRL), Follicle stimulating hormone (FSH), Luteinizing hormone (LH), Progesterone (P4), Growth hormone (GH), Insulin (INS), Thyroid hormone(T3and T4), Calcitonin (CT), Bone glad protein (BGP) by automatic chemical immune luminescence. Simultaneously, the concentration of serum Calcium (Ca) and Phosphorus (P) were detected by automatic biochemical analyzer. All these data were used to do a systematically analyse of the dynamic changes of the hormone and the correlation between them.The results showed that:(1) the content of serous P4maintained at a high level before prenatal15d, thereafter fell sharply and remained at a low level. The contents of serous PRL increased sharply on the day of childbirth, FSH stayed at a low level before prenatal5d, then increased gradually and maintained at a higher level during the postpartum stage. The content of serous LH showed a clear trend of slow decline after birth. All these data showed a significant difference between different times (P<0.05).(2) The content of serous GH rose slowly before prenatal15d, then fell sharply and stayed at a low level. The contents of serous T4and INS declined gradually until the day of birth (0d) and postpartum5d, respectively, then increased gradually. The content of serous T3increased on the day of birth (0d), and maintained at a high level in a period of the postpartum stage. All these data showed a significant difference between different times (P<0.05).(3) The contents of serous Ca and P declined gradually in prenatal until the day of birth (0d), and remained a stable level in postpartum. The content of serous BGP increased gradually before prenatal20d, and then decreased slowly. The content of serous CT fell sharply until the postpartum10d, then maintained in low level. All these data showed a significant difference between different times (P＜0.05).(4) The milk production rose slowly after childbirth, reached peak in postpartum35d, then maintained within a certain range.(5) The correlation analysis of all indicators above showed a highly significant positive correlation between serous INS and T4, P4, CT, BGP, Ca and P content (P＜0.01), but a highly significant negative correlation with PRL (P<0.01). There was a significantly positive correlation between the content of P and Ca (P＜0.05). In addition, the data showed a significant negative correlation between milk production and serous INS, T4, P, GH content (P＜0.01), but a significant negative correlation between milk production and serum Ca (P＜0.05). Simultaneously, there was no significant correlation among the rest of the indicators (P>0.05). There was a physiological negative balance of energy during the perinatal period of cow. In addition, the level of hormone, metabolism of calcium and phosphorus, milk production showed an interaction relationship between each other. The results showed illustrate the change of reproductive hormones in perinatal cows, confirmed that the variation of the hormones and calcium-phosphorus metabolism which was related to energy metabolism. Furthermore, there were complex correlations between the indicators measured.