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The relationships of growth, body shape, and body composition to the initiation of oestrous activity in different sheep breeds
Stephenson SK, Dalton DC, Kirton AH
Proceedings of the New Zealand Society of Animal Production, Volume 40, pp 258-267, Jan 1980
Proceedings of the New Zealand Society of Animal Production, Volume 40, pp 258-267, Jan 1980
Article class: Conference Presentation
Subject Terms: Bodyweight/liveweight/condition score, Breed/breeding, Fat/lipids, Genetics, Growth/development, Meat, Oestrus/oestrous, Puberty, Reproduction, Reproduction - female, Skeletal/bone/cartilage
Animal Type: Livestock, Production animal, Ruminant, Sheep
Publisher: New Zealand Society of Animal ProductionAbstract
Studies of between- and within-breed variation in oestrous activity and its relationships with body weight, shape and body composition were made on groups from the Whatawhata sheep breed comparison trial (Romney, Drysdale, Merino/Romney, Coopworth, Perendale, Cheviot, Dorset/Romney). Higher body weight, shorter cannon bones and slower growth in height at the withers were associated with a greater incidence of hogget oestrus. Breed comparisons of body composition showed an association between the autumn rate of increase in the proportion of body fat and the percentage of mated ewe hoggets. These relationships may be explained by the effects of pubertal sex hormone changes on bone growth at the epiphyses and a correlated increase in appetite. The results have implications for improving meat breeds, particularly when the desired types of livestock are lean and early maturing.The whole of the literary matter of the Proceedings of the New Zealand Society of Animal Production is copyright New Zealand Society of Animal Production, Downloading this article signifies agreement with the terms and conditions of electronic access.