PRODUCTION AND MANAGEMENT CONSIDERATIONS OF RUNNING WETHERS, HEMI-CASTRATES AND INDUCED CRYPTORCHIDS FOR WOOL PRODUCTION

Male, fine wool Merino sheep which had been subjected to different met hods of castration as lambs were assessed from 22 to 46 months of age for their suitability for wool production, their tolerance to posthiti s and their carcass characteristics. Hemi-castrates produced significa ntly (P<0,001) more clean wool than induced cryptorchids of a similar fibre diameter. Induced cryptorchids and hemi-castrates were significa ntly (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 hemicastration proved to be effective mean s of reducing the prevalence of posthitis such that as the degree of c astration decreased the proportion of animals with higher posthitis sc ores decreased (P<0.001). Testosterone levels in induced cryptorchids (1.01 ng/mL) and hemi-castrates with partial reduction of the parenchy ma (0.83 ng/mL) were similar, whereas hemi-castrates with complete red uction of the parenchyma in the 1 remaining testicle had a significant ly (P<0.001) lower level (0.32 ng/mL) and significantly (P<0.001) ligh ter testes. Development of horns and obvious scrotums by induced crypt orchids and hemi-castrates with partial reduction of the parenchyma in the 1 remaining testicle attracted penalty rates at shearing and slau ghter. Some induced cryptorchids and hemi-castrates exhibited masculin e behaviour, but they were unlikely to be fertile because although spe rmatozoa were present they were abnormal and/or non-motile. Hemi-castr ates with full reduction of the parenchyma in the 1 remaining testicle offer significant advantages over the other groups for wool productio n. Severe posthitis was not observed, they were infertile, they did no t attract penalty rates for shearing or slaughter and their clean flee ce 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 b e replaced with this type of partial castration in wool-producing floc ks.