State of Sexual Maturity of Nelore Bulls

Abstract

This research aimed to determine the state of sexual maturity of young Nelore bulls and its relation to scrotal circumference and seminal characteristics. 1985 animals (aged between 19 and 23 months), fed with tropical pastures (<em>Brachiaria brizantha, Brachiaria decumbes</em>, and <em>Panicum maximum</em>), were evaluated through andrological examination. Physical characteristics of the ejaculate, sperm morphology and scrotal circumference (SC) were examined. After the andrological examination, animals were classified as suitable for reproduction (andrological class 1) suitable for reproduction in natural mating system (class 2) temporarily unsuitable for reproduction (class 3) and discarded (class 5). To compare the measurements found in different andrological classes, two tests were used: the Tukey test with 5% probability of error, and simple Pearson correlations to verify the relationships between the studied characteristics. 84.5% of the bulls were found to be sexually mature. 39.75% of the animals suitable for reproduction presented a SC greater than 34 cm, and only 0.71% of the study population showed a scrotal circumference less than 28 cm. Favorable high correlations between SC and the physical characteristics of semen were evidenced. The article concludes that scrotal circumference is an excellent characteristics for evaluating and selecting young Nelore bulls.