Production and management considerations of running wethers, hemi-castrates and induced cryptorchids for wool production
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Published:1997
Issue:3
Volume:37
Page:303
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ISSN:0816-1089
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Container-title:Australian Journal of Experimental Agriculture
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language:en
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Short-container-title:Aust. J. Exp. Agric.
Author:
Foster F. M.,Jackson R. B.,Hopkins D. L.,Corkrey R.
Abstract
Summary. Male, fine wool Merino sheep which had been
subjected to different methods of castration as lambs were assessed from 22 to
46 months of age for their suitability for wool production, their tolerance to
posthitis and their carcass characteristics.
Hemi-castrates produced significantly (P<0.001) more
clean wool than induced cryptorchids of a similar fibre diameter. Induced
cryptorchids and hemi-castrates were significantly
(P<0.05) heavier than wethers. Partial hemi-castrates
and induced cryptorchids had significantly (P<0.001)
heavier and leaner carcasses (lower GR measurement) than wethers and
testosterone-treated wethers. Induced cryptorchidism and hemi-castration
proved to be effective means of reducing the prevalence of posthitis such that
as the degree of castration decreased the proportion of animals with higher
posthitis scores decreased (P<0.001).
Testosterone levels in induced cryptorchids (1.01 ng/mL) and
hemi-castrates with partial reduction of the parenchyma (0.83 ng/mL) were
similar, whereas hemi-castrates with complete reduction of the parenchyma in
the 1 remaining testicle had a significantly
(P<0.001) lower level (0.32 ng/mL) and
significantly (P<0.001) lighter testes.
Development of horns and obvious scrotums by induced cryptorchids and
hemi-castrates with partial reduction of the parenchyma in the 1 remaining
testicle attracted penalty rates at shearing and slaughter. Some induced
cryptorchids and hemi-castrates exhibited masculine behaviour, but they were
unlikely to be fertile because although spermatozoa were present they were
abnormal and/or non-motile.
Hemi-castrates with full reduction of the parenchyma in the 1 remaining
testicle offer significant advantages over the other groups for wool
production. Severe posthitis was not observed, they were infertile, they did
not attract penalty rates for shearing or slaughter and their clean fleece
weight, wool quality, carcass weight and grade were comparable with or
superior to wethers. To reduce dependence on synthetic hormones to control
posthitis, traditional complete castration techniques could be replaced with
this type of partial castration in wool-producing flocks.
Publisher
CSIRO Publishing
Subject
General Agricultural and Biological Sciences
Cited by
1 articles.
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