An attempt to suppress the rut-associated loss of live weight in
stags by immunocastration
G.K. BARRELL, A.M. NICOL AND M.J. KEELEY
Animal and Food Sciences Division, P O Box 84, Lincoln
University, Canterbury
E-Mail:
NZSAP 2002 Abstract No. 38
Proceedings of the New Zealand Society of Animal Production 62:
149-151
Two trials were conducted to study the effectiveness of
vaccination of stags against gonadotrophin-releasing hormone (GnRH) for
minimising the deleterious effects of the rut on their live weight and
body condition. In March 2000, mature red deer stags (n = 10) received a
s.c. injection of 1.0 ml of vaccine (Improvac®) or saline solution
(controls) and a second injection three weeks later. Liveweight loss in
the 10 weeks following the initial injection was not affected by the
treatment (mean loss 28.6 ± 4.0 kg and 28.1 ± 4.2 kg for
vaccinated and control groups, respectively). Plasma testosterone
concentration was lower (P<0.05) in the vaccinated stags but there
was no effect on scrotal diameter. In the following year, stags (n = 10)
were injected with 2.0 ml of the vaccine or saline on 18 January and 8
February. Mean liveweight loss in 21 weeks was similar for vaccinated
and control groups (41.2 ± 8.2 kg and 38.8 ± 7.2 kg,
respectively) and there was no treatment effect on the reduction in body
condition score. Although vaccinated stags had a lower (P<0.05) mean
plasma testosterone concentration than control stags, this effect can be
entirely attributed to stags (3 out of 4) that had been vaccinated in
the previous year’s trial. It is concluded that vaccination of stags
against GnRH does not overcome the loss in live weight which is
associated with the rut in these animals.
Keywords: NZSAPAB;
deer; stags; GnRH; immunocastration
Last Updated 30/07/2002
