Características andrológicas e do sêmen de touros do composto Red Norte (Nelore x Tabapuã x Red Angus x Sinepol)

Abstract

Reproductive traits of cross-breed Red Norte (Nelore x Tabapuã x Red Angus x Sinepol) young bulls averaging of 13.9±0.8 month-old were evaluated, in order to determine the puberty onset and semen quality in these animals. Scrotal circumference (SC), body weight (BW), and semen parameters of 70 bulls were measured. Animals were allotted in three groups (G) according to their SC: GI=27-33cm (n=24), GII=33-35cm (n=24), and GIII=35-43cm (n=22). BW and age of each group were, respectively: GI=411.2±37.4kg and 13.8±1.0 month-old, GII=426.9±31.5kg and 14.0±0.7 month-old, and GIII=438.4±38.3kg and 14.0±0.6 month-old. Seminal physical characteristics for same order of groups were: volume 4.2±3.1mL, 5.3±2.6mL, and 4.5±2.1mL; motility 31.3±24.1%, 44.2±23.9%, and 43.9±21.5%; and vigor 2.8±1.6, 3.5±1.3, and 3.5±1.3. The spermiogram presented concentration values of 130.5±266.2x106/mL, 289.5±390.2x106/mL, and 333.9±523.7x106/mL; total defects of 81.4±15.9%, 73.8±15.4%, and 67.9±19.0%; major defects of 87.3±26.2%, 66.8±24.9% and 56.7±17.1%; and minor defects of 16.6±14.9%, 33.2±24.9%, and 43.3±17.1%, for same order of groups. Seven out of 70 bulls were considered satisfactory potential breeders. Results showed that semen pathology progressively decreased when SC increased.