Authors: Cahit KALKAN, Halis ÖCAL
Abstract: The aim of this study was to determine the influence of external oestrogen hormones on initiating luteolysis. A total of 8 cows were included in the study. After the detection of first oestrus cycle, blood samples were collected 3 times a week thought the cycle. During the second oestrus cycle, animals were divided 2 groups. The first group animals received 25 mg diethylstilbestrol (DES) intra muscularly between 10th and 13th days of the cycle. The second group animals were given estradiol valerate (EV) at 5 mg/animal intra muscularly. Blood samples were collected as done during the first cycle. Progesterone levels in the blood samples were detected in a Radio Immuno Assays (RIA). Average oestrus cycles in the animals given DES were 20.25±0.75 and 19.50±0.50 day before and after the DES administrations, respectively. These values were 21.25±1.44 day and 16.50±0.96 day in EV administered animals, respectively. In conclusion, a single dose DES or EV administration during the mid period of the oestrus cycle seems to effect the initiation of luteolysis in cows.
Keywords: Estradiol valerate, Diethylstilbestrol, Luteolysis, Cow