The Effects of Immunological Castration on the Testicular Function of Boars Given Two Different Anti-GnRH Vaccinen

Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Christopher A. Pearl

Second Advisor

Dr. Christine Byrd-Jacobs

Third Advisor

Dr. Jeffrey Watts


Immunocastratic, HPG axis, anti-GnRH, Improvac, Bopriva

Access Setting

Masters Thesis-Abstract Only

Restricted to Campus until



This study investigates the reproductive effects of two anti-GnRH vaccines (Improvac®, Bopriva®) in boars . Animals are vaccinated with either Improvac or Bopriva and then observed for ten weeks after the second injection. Blood samples show that GnRH antibody titers rapidly begin to rise after the second vaccination and reach peak values approximately 2 weeks later. At the same time testosterone concentrations decrease to undetectable levels and remain low for six weeks. Testosterone then begins to increase in animals treated with Improvac though levels remain decreased in Bopriva treated animals throughout the ten weeks. Ten weeks after the second injection daily sperm production is significantly reduced in both treatment groups, however, the reduction is greater in Bopriva treated boars. Examination of testes for both treatments shows incomplete spermatogenesis with impaired spermatid production and reduced seminiferous tubule diameter. These findings are universal in Bopriva treated animals but Improvac treated animals exhibit results intermediate between Bopriva treated animals and control boars. Together these results indicate that Bopriva provides a longer duration of immunity than Improvac and is effective in suppressing testicular function and testosterone secretion for at least 10 weeks after the booster injection.


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