In Journal of Swine Health and Production, Dr David Hennessy of David Hennessy Consulting in Australia and others in Brazil, the US and Australia have reported their study to evaluate the effects of one dose of an anti-gonadotropin releasing factor (GnRF; (Improvac; Zoetis, Florham Park, New Jersey) vaccine on testicular development, sexual behaviour and sperm characteristics in young boars.

The researchers allocated a total of 48 pigs equally to two treatments, controls and immunised, with a single dose of an anti-GnRF vaccine at 16 weeks of age.

Sexual behaviour was evaluated five to eight weeks later.

Of these 48 pigs, 22 (12 controls, 10 immunised) underwent weekly semen collections for 14 consecutive weeks, starting 17 weeks after immunisation. One week after completion of the weekly collections, six boars per treatment underwent daily collections for seven 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.

The researchers found no statistical differences between treatments in gonad size, the sexual behaviour 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 immunised pigs.

Under the conditions of this study, Hennessy and co-authors concluded that one dose of an anti-GnRF vaccine given to 16-week-old boars had no effect on testicular development, sexual behaviour or sperm characteristics.

They added that, 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.

Reference

Scheid I.R., F.T.T. Oliveira Jr, A.C. Borges, T.F. Braga, R.A. Soncini, S. Mathur, J.R. Allison and D.P. Hennessy. 2014. A single dose of a commercial anti-gonadotropin releasing factor vaccine has no effect on testicular development, libido, or sperm characteristics in young boars. J Swine Health Prod. 22(3):185–192.

September 2014