The present study aimed to evaluate the efficiency of Ovsynch treatment associated with prefixed-time artificial insemination on Bos taurus and Bos indicus cows. Herds of Holstein, Caracu, Nelore and Mantiqueira breeds were used. A herd of Gir cows with poor reproductive performance was also included. Each breed was divided in tree groups. Group 1 received Ovsynch treatment and was inseminated at prefixed time. Group 2 was induced to estrus with cloprostenol and inseminated thereafter. Group 3 was inseminated at natural heat. Conception and pregnancy rates were determined by ultra-sound. No significant interactions were detected among breeds, age, parity, postpartum period and lactating cows with or without their calves. Conception rates did not differ (P>0.05) among groups while pregnancy rate was higher (P<0.05) for group 1 and 2 comparing to group 3. In the Gir herd Ovsynch treatment did not enhance conception nor pregnancy rates. Independently of breed, conception rate is similar after Ovsynch, cloprostenol and control treatments, and pregnancy rate can be improved with Ovsynch and cloprostenol treatments. In cows with unspecific reproductive ovarian disorders, Ovsynch treatment do not enhance conception or pregnancy rates.
cattle; reproductive performance; ovulation; synchronization; fertility
) ou no cio natural (Controle)(1). 