RESUMO
The study was conducted to evaluate estrus response, time to the onset of estrus, and conception rate at fixed time AI and AI at detected estrus in local and crossbred heifers and cows subjected to double administration of PGF2α. One hundred twenty local (heifers, n = 27; cows, n = 33) and crossbreds (heifers, n = 21; cows, n = 39) were used for the study. About 63 and 85.7 % of the local and crossbred heifers, respectively, exhibited estrus. Similarly, all crossbred cows and 90.9 % of local cows showed estrus. Most heifers came to estrus between 48 and 72 h while cows exhibited behavioral signs of estrus between 72 and 96 h. AI at detected estrus resulted in higher conception rate than fixed time AI. Pregnancy per artificial insemination was higher in AI at detected estrus than fixed time AI. Accurate estrus detection followed by insemination are crucial factors in maximizing pregnancy, and this study has demonstrated that conception rate in smallholder heifers and cows should be inseminated following estrus detection to maximize the conception rate of the animals.
