The objective of this research was to compare the effects of different doses of application of sodic cloprostenol (doses equivalent to 50% the conventional), in the intramuscular (IM) and intra-vulvosubmucosal (IVSM) vias on the synchronization rates, interval of application to estrus and decrease of seric progesterone concentrations. One hundred and ninety-nine females, 103 with of previus report estrous and 96 without report of previus estores evaluated by rectal palpation to verify the presence of corpus luteum, were randomly divided into three treatments: 1 - 68 animals (38 with report of previous estrus) received 1 mL of cloprostenol through IVSM; 2 - 66 animals (33 with report of previous estrus) received 1 mL through IM; 3 - 65 animals (32 with report of previous estrus) received 2 mL through IM. It was considered the animals that showed estrus up to 96 hours after cloprostenol application. The seric progesterone concentrations (P4) were analyzed by RIA at 0 and 48 hours after the application of luteolitic drug. No effects of treatments on synchronization rates (72.1, 53.0, and 64.6%, respectively), interval from application to estrus (69.3 ± 15.2, 67.9 ± 16.7, and 68.3 ± 16.9 hours, respectively) and P4 percentage concentration decrease (79; 68 and 83%, respectively) were observed. However, when data of animals from treatments of days 11 to 16 were grouped and compared to those of treatments of days 7 to 10, the synchronization rates differed (76.1% vs 55.5%). Sodic cloprostenol doses that was reduced by 50%, in IM or IVSM vias, showed effect similar to the conventional dose. Animals during days 11 to 16 respond better to a synchronization with cloprostenol than those during days 7 to 10 of diestrus.
cloprostenol; synchronization; progesterone; estrus; pregnancy; bovine
