CHANGS IN THE LEVEL OF MILK PROGESTERONE IN COWS WITH PERSISTENT CORPUS LUTEAL AND LUTEAL CYST DURING OXYTOCIN-THERAPY
Duan Enkui Liu Zhixi Wang Jianchen (Laboratory of Reproductive Endocrine in Domestic Animals,Northwestern Agricultural University,Yangling)
The level of milk progesterone ( P4 ) in cows with persistent corpus luteam ( PCL ) and luteal cyst ( LC) during oxytocin-therapy was determined by radioimmunoassay ( RIA ).The mechanism of oxytocin induced luteolysis in the cow also discussed. Thirty seven lactating holstein cows with PCL or LC were divided into 2 groups.Cows in group 1 (31 cases ) were given intramuscularly 400 I.U.oxytocin,which were divided into 2 or 4 equal doses and given at 2 h intervals.Cows in group 2(6 cases ) were given intramuscularly 4 mg 15 methyl-PGF2α. The levels of milk P4 for group 1 and group 2 at 24 h before injection were 8.30±1.18 and 8.75±1.17ng/ml respectively,and levels were shifted to 1.83±0.55 and 1.35±0.71 ng/ml respectively after injection.The values after injection were significatly lower than those before injection(P0.01).