Onset Of Puberty In Pasture-raised Thoroughbreds Born In Southern Hemisphere Spring And Autumn
CG Brown-Douglas, EC Firth, TJ Parkinson, PF Fennessy. Onset of puberty in pasture-raised Thoroughbreds born in southern hemisphere spring and autumn. Equine Veterinary Journal 36, 499-504, 2004.
Abstract
OBJECTIVES:
To examine the age, bodyweight and date of onset of puberty in Thoroughbreds born in spring and autumn.
CONCLUSIONS AND POTENTIAL RELEVANCE:
Seasonal changes in photoperiod affect the timing of onset of puberty, provided a minimum threshold bodyweight has been reached. Spring–born horses reached this threshold weight during the winter months and remained reproductively inactive until after the stimulus of increasing day-length occurred. The autumn–born horses reached the threshold weight to support puberty at the same time as stimulatory photoperiod and, therefore, reached puberty significantly younger and lighter than the spring–born horses.