[Reproductive performance of Bos taurus x Bos indicus heifers following artificial insemination after spontaneous estrus in the dry tropics of Costa Rica] | Comportamiento reproductivo de novillas Bos taurus x Bos indicus inseminadas artificialmente a estro natural en el tropico seco de Costa Rica

English. In order to evaluate the reproductive performance of beef heifers artificially inseminated in the dry tropic conditions in Costa Rica, 409 Bos taurus x Bos indicus heifers ranging from 2.1 to 4.6 years of age were used. Heifers were divided into two groups. Estrus detection in each group was carried out by the visual method twice a day. Additionally, in each group of the heifers, two bulls with penial deviation were equipped with chin-ball-marker. Sixty six point five percent of the heifers were detected in heat during the first 21 days and 81.6% during the overall period of 47 days. The average interval between the two consecutive inseminations were 20.2+-1.5 days (ranging from 16 to 24). Eighty six point five percent of the inseminated heifers were pregnant after artificial insemination AI and 88% after AI plus natural breeding. The pregnancy rate was 70.6% as a result of the AI and 76% as a result of the AI plus natural breeding. The number of services per conception of pregnant heifers was 1.53. This study suggests that improving management, nutrition and selection of replacement heifers can lead to satisfactory percentage of fertility in Bos indicus cattle by the strategic use of artificial insemination

Spanish; Castilian. Con el fin de evaluar el comportamiento reproductivo de novillas de carne inseminadas artificialmente en condiciones del tropico seco de Costa Rica, se utilizaron 409 novillas Bos taurus x Bos indicus de 2.1 a 4.6 anos de edad. Las novillas se manejaron en dos grupos que se denominaron programas 1 y 2. La deteccion de estros en cada grupo fue realizada mediante dos observaciones diarias. Se conto ademas, en cada grupo, con la ayuda de 2 toros con pene desviado equipados con marcador de barbilla. El 66.5% de las novillas fueron detectadas en celo durante los primeros 21 dias y 81.6% durante el periodo de 47 dias que duro el programa. El intervalo promedio entre dos servicios consecutivos fue de 20.2+-1.5 dias (entre 16 y 24 dias). El 86.5% de las novillas inseminadas quedaron gestantes de inseminacion artificial y 88% despues de la inseminacion artificial mas la monta natural, el porcentaje de prenez de inseminacion artificial fue de 70.6, en tanto que el acumulado en la monta natural fue de 76. El numero de servicios por concepcion de las novillas gestantes fue de 1.53, lo anterior sugiere que se pueden lograr porcentajes de fertilidad satisfactorios en el ganado Bos indicus con el uso estrategico de la inseminacion artificial