The relationships of growth, body shape, and body composition to
the initiation of oestrous activity in different sheep breeds
S.K. Stephenson and D.C. Dalton, A.H. Kirton
University of New England, Armidale, Australia and Ruakura
Animal Research Station, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1980, 40: 258-267
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.
Keywords: NZSAPAB;
Last Updated 12-09-1998
