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dc.contributor.authorMahgoub, O.en
dc.contributor.authorBarrell, Graham K.en
dc.contributor.authorSykes, Andrew R.en
dc.date.accessioned2008-03-28T00:30:21Z
dc.date.issued2001-11en
dc.identifier.citationMahgoub, O., Barrell, G. K., & Sykes, A. R. (2001). Effect of gender, gonadectomy and oestradiol-17β on growth in lambs under grazing conditions. Journal of Agricultural Science, 137(3), 351-364.en
dc.identifier.issn0021-8596en
dc.identifier.urihttps://hdl.handle.net/10182/402
dc.description.abstractTo identify separate effects of gender, castration and exogenous oestrogen on growth, castrated lambs of both sexes and entire male lambs (n = 8) were implanted subcutaneously with three sizes of oestradiol-17β implants, or not implanted, and grazed on ryegrass and white clover pasture for 180 days. A group of non-implanted entire female lambs (n = 8) was run together with the others. Non-implanted entire male lambs grew faster, had heavier heads, less internal, non-carcass fat and more protein and less fat and water in the carcass than non-implanted entire females. In addition, they had higher 12th vertebral spine, thicker tibia, and heavier and larger humerus than entire female lambs. Castration of male lambs reduced live-weight gain, weight of head and content of protein in the carcass whereas it increased carcass fat content. In addition, it caused lengthening of cannon bones and reduced height of 12th vertebral spine and length of tibia. In females, gonadectomy increased height of 12th vertebral spine and diameter to length ratio of the radius. Oestradiol treatment increased live-weight gain, reduced total internal and carcass fat, and increased water and protein content of the carcass in gonadectomized animals of either sex, and increased weight of carcass and head in spayed ewe lambs. Oestradiol treatment inhibited longitudinal growth of cannon bones and stimulated that of vertebral column and ribs, but had little effect on the dimensions of limb bones apart from increasing their diameter. Oestradiol treatment had no effect on muscle length but increased muscle girth and weight, except for m. splenius in ram lambs where muscle weight was reduced. Effects of oestradiol on skeletal measurements in most cases were linearly related to dose of oestradiol. It was concluded that the variable effects of sex steroids on the skeleton were related to the differential pattern of skeletal maturation. In early maturing bones acceleration of the growth process by an exogenous sex steroid caused elongation to cease prematurely, whereas in late-maturing bones the acceleration effect on elongation did not result in premature cessation. This observation may explain the often contradictory reports in the literature on the effects of sex steroids on linear growth of bone.en
dc.format.extent351-364en
dc.language.isoenen
dc.publisherCambridge University Pressen
dc.relationThe original publication is available from - Cambridge University Pressen
dc.rightsCopyright © 2001 Cambridge University Pressen
dc.subjectlambsen
dc.subjectgrowthen
dc.subjectsex steroidsen
dc.subjectgenderen
dc.subjectAgronomy & Agricultureen
dc.titleEffect of gender, gonadectomy and oestradiol-17β on growth in lambs under grazing conditionsen
dc.typeJournal Article
dc.subject.marsdenFields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300400 Animal Production::300406 Animal growth and developmenten
lu.contributor.unitLincoln Universityen
lu.contributor.unitFaculty of Agriculture and Life Sciencesen
lu.contributor.unitDepartment of Agricultural Sciencesen
dc.subject.anzsrc07 Agricultural and Veterinary Sciencesen
dc.relation.isPartOfJournal of Agricultural Scienceen
pubs.issue3en
pubs.organisational-group/LU
pubs.organisational-group/LU/Agriculture and Life Sciences
pubs.organisational-group/LU/Agriculture and Life Sciences/AGSC
pubs.organisational-group/LU/Research Management Office
pubs.organisational-group/LU/Research Management Office/QE18
pubs.publication-statusPublisheden
pubs.volume137en
dc.publisher.placeTorontoen
lu.identifier.orcid0000-0001-7644-6816


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