THE EFFECTS OF LUPROSTIOL ON THE ESTROUS- CYCLE AND PREGNANCY RATE OFHEIFERS AND COWS

The effects of luprostiol injections in early (days 5 to 9 of the cycl e) and late (days 10 to 15 of the cycle in heifers and days 10 to 14 i n cows) dioestrus on the injection-oestrus interval and pregnancy rate s were examined after fixed time inseminations at 72 and 96 hours afte r administration to 36 animals. The injection-oestrus interval for the early and late stages were 49 and 53.75 hours in heifers (P>0.05) and 48.86 and 71.75 hours in cows (P<0.001). Pregnancy rates in heifers a nd cows injected with luprostiol at the late stage of diestrus were 75 %. However, in heifers and cows following injections with luprostiol at early diestrus, pregnancy rates were 30 and 40 %, respectively.As a conclusion, injection-estrus intervals in animals received luprostiol injections at early diestrus were shorter than those of animals recei ved luprostiol at late diestrus. It has been considered that fixed tim e inseminations at the 72 and 96 th hours after luprostiol injections aren't favourable for the animals receiving luprostiol at early diestr us and the inseminations should be held earlier than 72 th hours or fo llowing the estrus detection.