Testicular characteristics of bulls immunosterilized with anti-luteinizing hormone-releasing hormone vaccine

The objective of this study was to evaluate the immunosterilization action of the anti-luteinizing hormone-releasing hormone (LHRH) vaccine, composed with ovalbumin-LHRH-7 and thioredoxin-LHRH-7, in Nelore-cross bulls. Twenty-six 2-year old bulls were randomly assigned in two groups of 13 animals each. The animals of group I received a primary and two booster injections of the vaccine on days 0, 141, and 287 of the experiment. In group II, the control group, the bulls did not receive any type of treatment. Scrotal circumference was measured in the beginning of the experiment and at slaughter, after 741 days. A testicular sample was collected at slaughter and processed for histological evaluation. The scrotal circumference in the immunized group was smaller, 22+/-5.98 cm, compared to the one of the control group (35.6+/-2.4 cm) , at slaughter. Histological analyses of the testis showed testicular degeneration and absence of sperms in 85% of the animals in the treated group, and a reduced number of sperms in the other 15%, in comparison to the control group. The vaccine anti-LHRH with protein fusion is effective in immune castration of bulls and should be considered as an alternative tool for extensive live stock production in Brazil.