Estrous synchronization in the gaur (Bos gaurus): Behavior and fertility to artificial insemination after prostaglandin treatment

Abstract

The gaur (Bos guarus) is an endangered species that is a wild ancestor of domestic cattle. This study was conducted to evaluate 1) the efficacy of prostaglandin F2α (PG) to synchronize estrus in gaur, 2) behavior of male and female gaur around estrus, and 3) fertility after artificial insemination (AI) at the PG-induced estrus. Six female gaur were utilized, along with a vasectomized gaur bull used to aid in detecting estrus. All females were given two i.m. injections of PG (25 mg/injection) 11 days apart, and monitored for estrus for 120 hr (48 hr via chinball marks, followed by 72 hr continuous observation) after the second PG injection. Three of the six females were in estrus during the 120-hr evaluation period. One female was in estrus prior to 48 hr after the second PG injection, and two females were observed in estrus during the 72-hr continuous observation period. When a female was observed in estrus (standing to be mounted by the vasectomized bull), she was bred by AI at 12 and 24 hr after the onset of estrus. The four females not observed in estrus, including the one marked during the first 48 hr, were bred by AI at 80 and 92 hr after the second PG injection. Of the two gaur females observed in estrus, one female was first mated by the vasectomized bull at 77 hr and the second female was mated at 98 hr after PG. Both females exhibited very short durations of receptivity (less than 4 hr). The second female observed in estrus became pregnant after AI and gave birth to a healthy gaur calf after a 299-day gestation. It appears that female gaur can be synchronized with PG techniques developed for domestic cattle. These data should provide useful information for programs studying and maintaining this endangered species and may have relevance for the cattle industry, since the gaur could provide a source of diverse ancestral genetic material.