The effect of immunological castration on behaviour and growth of
young bulls
J.G. Jago, R.R. Lasenby, T.E. Trigg, P.D. Claxton, L.R. Matthews, J.J.
Bass
University of Waikato, Biology Department, Hamilton, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 190-192
This study aimed to raise GnRH antibodies in young bulls
(immunocastration) and determine the subsequent effect on behaviour,
sexual development, carcass characteristics and meat quality. Thirty Friesian
bull calves were assigned to one of three groups balanced by liveweight
(control bulls, immunocastrates and steers). At nine months of age (Day 0)
immunocastrates were vaccinated against GnRH (Vaxstrate) and boosted one
month later (Day 31). Following immunisation there was a rise in GnRH
antibody titre and a decrease in testosterone. Control animals gained
significantly more weight than immunocastrates and steers in the first 157
days. Overall there was no difference in weight gain between controls and
immunocastrates. Mean scrotal diameter of immunocastrates decreased from
Day 31 to Day 110 and then rose to reach a diameter similar to those of the
control bulls by Day 322. Leg wear scores were lower for treated animals
compared to controls until Day 230 of the trial, although these differences
were not significant. Immunocastrates had a significantly higher mean
ultimate pH than both control bulls and steers. Bulls were significantly
leaner than immunocastrates, and both groups were leaner than steers.
Keywords: NZSAPAB;
immunological castration; bull behaviour; meat quality; growth
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Last Updated 25-01-1997
