Measures of stress and growth suppression in surgically castrated bulls
J.F. Carragher, T.W. Knight, A.F. Death, J.R. Ingram and L.R.
Matthews
Animal Behaviour and Welfare Research Centre, AgResearch,
Ruakura Agricultural Centre, Private Bag 3123, Hamilton.
Proceedings of the New Zealand Society of Animal Production. 1997,
57: 100-104
The effects of surgical castration of pre- and post-pubertal
bulls on measures of stress and growth were investigated in two separate
experiments. In Experiment 1, 17-month-old Friesian bulls (n = 6 per
treatment) were either left untreated (Controls), handled and
administered local anaesthetic (Handled), or handled, administered local
anaesthetic and surgically castrated (Castrates). In Experiment 2,
5-month-old Friesian bulls (n = 10 per treatment) were either left
untreated (Controls) or surgically castrated without local anaesthetic
(Castrates). Castrates in Experiment 1 had higher (P<0.05) plasma
cortisol concentrations 7 and 14 days after treatment compared with
Handled bulls and lower (P<0.01) gains in body weight for 14 days
compared with Controls. There were no effects of treatment on plasma
non-esterified fatty acid, Beta-hydroxybutyrate and urea concentrations.
Castrates in Experiment 2 had higher (P<0.05) plasma concentrations of
cortisol and the inflammatory protein haptoglobin for 7 days after
treatment compared with Controls. The feed intake and weight gain of
Castrates were also lower (P<0.05) than that of Controls during the week
following treatment. It is concluded that the castration of cattle
causes stress, resulting in a check in growth which is possibly mediated
via a reduction in feed intake.
Keywords: NZSAPAB;
growth suppression; castration; cortisol; testosterone; stress.
Last Updated 12-09-1998
