This study aimed to evaluate the sexual behavior of 88 bulls of the Angus and Zebu (Gyr, Guzerat and Nellore) breeds managed for collection and processing of semen at an artificial insemination center. On average, bulls were at 5 years of age, 906 kg of live weight and 41 cm for scrotal circumference. Reaction time in all breeds was positively influenced by the "moving" stimuli teaser. Reaction time in Angus bulls was smaller than in bulls of the zebu breeds and longer in older than in younger bulls. The daily mount order did not influence the reaction time. All sexual behavior traits in the Angus bulls were close to complete mount with artificial vagina. The behavior for "smelling and licking the genitalia", "beating using the head or the horn", "drip of seminal liquid", "erection and penis protrusion" and "aborted mount" were more usual in zebu than in Angus bulls. Among zebu breeds "prepuce contraction" and "aborted mount" were more frequent in Nellore than in Guzerat bulls and "complete mount without end force" was more observed in Nellore and Guzerat than in Gyr bulls.
bulls; ethology; Gyr; Guzerat; Nellore
