Efeito da imunocastração sobre o perímetro escrotal e a produção espermática em touros da raça nelore

Bopriva® exerts anti-gonadotropin-releasing hormone (GnRH) activity and is used for immunocastration of cattle. The objective of this study was to evaluate the effect of Bopriva® on scrotal circumference and sperm production and quality of Nellore bulls. Five Nellore bulls (Bos taurus indicus), aged 12 months, received two doses of Bopriva® at an interval of 30 days, with each dose of 1 mL/animal containing 400 μg of the product. At 2-weeks intervals, scrotal circumference was measured and semen was collected by electroejaculation (seven samplings) and submitted to physical and morphological analysis. Scrotal circumference significantly decreased after the 4th sampling (P=0.0056) and sperm motility ranged from 20% to 66% (mean of 39%), sperm vigor from 1.0 to 2.8 (mean of 1.74), and sperm concentration from 87.8 to 296.2 million spermatozoa per mL (mean of 242.9 million). The percentage of total sperm defects ranged from 36% to 75.6% (mean of 49.51%), with a high incidence of cytoplasmic droplets, bent tails and detached heads. Bopriva® reduces scrotal circumference and interferes with semen quality in Nellore animals, reducing sperm motility and increasing the percentage of sperm abnormalities in the ejaculate.