The use of D- and L,D- cloprostenol to reduce diastral period of estrus cycle in mares

Abstract

In order to determine the minimum effective drug doses, the levels of decrease in progesterone concentration followed the injections of D and L, D - cloprostenol (the dosage 25 - 250 μg) were compared. The effect of treatment on the reduction of estrus duration and the time before ovulation were studied. It has been shown that the level of progesterone 24 hours after the first injection (at any dose except 50 μg of L, Dcloprostenol) decreased by 76-81%. Complete luteolysis was achieved (0.24-0.45 ng/ml) at any kind of treatment in 72 hours after injection. A significant difference in the average duration of estrus (when using large doses) and the period from injection to ovulation (when using small and large doses) was found between groups of mares that were injected with a follicle diameter of 22-28 or 29-37 mm in both the first and in the second half of diestrus. The study showed that the use of D-cloprostenol once in reduced doses (25 - 50 μg) or D, L-cloprostenol twice 50 μl in the presence of follicles more than 29 mm in diameter will decrease the risk of reducing the duration of estrus.