In this study, the effectiveness of a reduced dose of cloprostenol injected by inlravutvo-submucosal route was evaluated for estrus induction and luteolysis in cows. The study was carried out on 43 Brown Swiss cows, age ranging 3 to 5 years old. Firstly, allcows were injected 500 mcg of cloprostenol by intramuscular route. On the 11 th. day, cows in the first group (n: 38). Were reinjected 125 mcg of cloprostenol by intravulvo submucosal route and the remaining cows ir, the second group (n:5) were administered an injection of 500 meg cloprostenol intramusculary. Blood samples to determine the plasma progesterone levels were collected on the day of second injection and four days thereafter from 9 and 5 cows in the first and second groups, respectively.

According to the obtained results; estrus rates in first and second groups were 26.3 and 100 %, respectively. On the basis of the 7 cows inseminated in the first group, pregnancy rate was 57.1 %. Progesterone levels of the cows in the first group decreased after the second injection. Although a slight decrease in progesterone levels was monitored in the cows with no luteal regression, it was never below 1 ng/ml. The progesterone levels of the cows in the first group with luteolysis showed a sharp decline compared to the control group.

As a result, application of 125 meg of cloprostenol injection into vulvar sub mucosa induced estrus and luteolysis in cows. It was concluded that the higher doses of cloprostenol administrations by intravufvo-submucosal injections may provide better results in cows.