Abstract

Twenty one Romney ewes were housed indoors for 12 months from February to determine the effect of season, pregnancy and lactation on wool growth. Ten ewes were naturally mated in April to lamb in September. The ewes were fed to maintain constant maternal body weight and a midside patch harvested monthly to determine clean fleece growth rates. An effect of pregnancy on individual fibre length growth rate, determined by autoradiography, occurred as early as 21-35 days after joining. During the second month of gestation, fleece production and mean fibre diameter fell below that of non-pregnant ewes and continued to diverge until parturition. Wool production rose in the non-pregnant group from August, but did not increase in lambing ewes until after parturition. These data suggest that pregnancy is associated with an early hormonally-mediated depression in follicle output superimposed on the decline associated with winter photoperiod.

AJ, Pearson, PE Kendall, MG Ashby, and JE Wildermoth

Proceedings of the New Zealand Society of Animal Production, Volume 59, , 30-33, 1999