Evaluación del efecto de hCG y GnRH sobre la tasa de concepción en vacas Holstein de primer servicio en tres hatos lecheros localizados en el Cantón Mejía

摘要

An experiment was conduced to evaluate whether the administration of human chorionic gonadotropin (hCG) or gonadotropin releasing hormone (GnRH) at the time of artificial insemination (A.I.) increase the conception rate on first service Holstein cows in three farms located at Macahchi valley in Ecuador. 66 healthy cows were selected with no more than 4 parturitions and with 45 - 60 days post partum. Corpus lutheum was detected by rectal palpation prior to the administration of one or more PGF2α doses until estrus was detected. At the time of A.I., cows were divided in three groups: hCG (n=22) administrated 2500 U.I., GnRH (n=22) administrated 0,25 mg, and control (n=22) administrated 2,5ml of saline solution. All the administrations were performed intramuscularly.