A single dose of a commercial anti-gonadotropin releasing factor vaccine has no effect on testicular development, libido, or sperm characteristics in young boars

Abstract

Objectives: To evaluate the effects of one dose of an anti-gonadotropin releasing factor (GnRF) vaccine on testicular development, sexual behavior, and sperm characteristics in young boars. Materials and methods: A total of 48 pigs were equally allocated to two treatments, Controls and Immunized, with a single dose of an anti-GnRF vaccine at 16 weeks of age. Sexual behavior was evaluated 5 to 8 weeks later. Of these 48 pigs, 22 (12 Controls, 10 Immunized) underwent weekly semen collections for 14 consecutive weeks, starting 17 weeks after immunization. One week after completion of the weekly collections, six boars per treatment underwent daily collections for 7 days. Blood for testosterone analysis was collected from seven animals per group at 0, 2, 4, 8, 12, 16, 20, 24, and 28 weeks post immunization. Results: There were no statistical differences between treatments in gonad size, the sexual behavior test, qualitative and quantitative semen characteristics, sperm morphology, time to mount, ejaculation time, or serum testosterone concentrations. There was no histological evidence of an alteration in onset and development of puberty in the immunized pigs. Implications: Under the conditions of this study, one dose of an anti-GnRF vaccine given to 16-week-old boars has no effect on testicular development, sexual behavior, or sperm characteristics. As final replacement-boar testing is typically conducted after 24 weeks of age, a priming dose of vaccine could be given prior to boars undergoing final testing without negative impact on testicular development and future breeding potential.