EVALUATION OF THE EFFECTS OF ROUTE OF ADMINISTRATION OF CLOPROSTENOL ON SYNCHRONIZATION OF ESTRUS IN DIESTRUS DAIRY-CATTLE

Cloprostenol was administered IV or IM to diestrous dairy cows to stud y luteolysis and synchrony of estrus and ovulation. In Study 1, 28 Hol stein cows were assigned to receive injections of cloprostenol, IV or IM, on day 8 or 10 of the estrous cycle. Differences in cloprostenol-i nduced luteolysis or interval to estrus, were not detected. Ultrasonog raphy revealed that 2 cows treated IV on day 8, 1 cow treated IM on da y 8, and 2 cows treated IV on day 10 did not ovulate despite evidence of an apparently normal estrus. In Study 2, 20 Holstein cows were assi gned to receive cloprostenol injections, IV or IM, on day 10 of the es trous cycle. Interval to estrus was not affected by route of administr ation. Analysis of these data indicated that cloprostenol given Iv did not alter luteolysis or improve synchrony of estrus and ovulation whe n compared with cloprostenol given IM.