Abstract

Selection for out-of-season breeding ability could be enhanced if an early indication of the trait was available. The onset of hogget oestrus has been proposed as such a trait and has been examined for 362 ewe progeny coming from early and late-lambing selection lines over 3 years. In each year the early lambing (BV-) hoggets had an earlier (P<0.05) mean date of onset of oestrus than the hoggets from the late-lambing (BV+) line. In 1992 and 1993 this effect was confounded by the season of birth such that nearly all the BV- animals were autumn born (AB) and the BV+ animals born in the spring (SB). In 1993 animals from both lines were produced in both seasons. Their mean day of first oestrus in 1994 (expressed as day of year

AH, Kirton, GJK Mercer, JN Clarke, JL Dobbie, DM Duganzich, and JA Wilson

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 108-110, 1995