EFEITO DA ADMINISTRAÇÃO DO HORMÔNIO CORIÔNICO GONADOTRÓFICO (hCG) NA DURAÇÃO DO CICLO ESTRAL E NA TAXA DE PRENHEZ EM BOVINOS DE CORTE

No experimento foram utilizados 62 animais da raca Charolesa e Caracu, inseminados artificialmente (IA). No 7o dia apos a IA, as vacas foram divididas aleatoriamente em 2 grupos: tratado (n=32), que recebeu 2.500 UI de hCG (IM) e controle (n=30), que recebeu 1 ml de solucao fisiologica esteril, (IM). O diagnostico de prenhez foi realizado por toque retal no 45o dia apos a IA. Resultados: A duracao do ciclo estral diferiu (P 0,05) entre o grupo tratado e controle (40,62% e 23,33%, respectivamente). Conclusoes: A duracao do ciclo estral dos animais tratados foi prolongada em relacao aos controles (P 0,05) as taxas de prenhez em bovinos de corte. Effect of human chorionic gonadotropin (hCG) on estrous cycle length and pregnancy rates in cattle Abstract In the present experiment a total of 62 cows of Charoles and Caracu breeds, artificially inseminated (AI). At day 7th after AI the cows were aleatory distributed in two groups: treated group (n=32) that receive 2.500 UI of human chorionic gonadotropin (hCG) by the intramuscular route and control group (n=30) to wich 1.0 ml of sterile physiological solution was administered also by the intramuscular route. It has been found that the estrous cycle lenght was different (P 0,05) between treated and the control groups (40,6 and 23,3%, respectively). In this way, the estrous cycle lenght of the treated cows was extended in regard to the control cows. The hCG administration did not increase pregnant rates.