Abstract

Mature Merino ewe data (1988 to 1995) from 1407 ultrafine (UF) fibre diameter selected and 249 random controls (CF) totalling 3213 and 765 records respectively were analysed. Mean fibre diameter (FD) was significantly (P<0.001) lower in UF compared with CF (17.7 mm vs. 20.0 SED 0.04). Mean FD decreased in UF adult ewes by 0.16 um (±0.02) per year relative to CF. There were no differences for autumn live weight but UF was significantly lower for spring live weight (P<0.05) and fleece weight (P<0.01) and higher for fleece yield (P<0.01) than CF. There were significant (P<0.001) age effects for all of these traits. For those ewes born during the project (1990-1994), the number of lambs born per ewe was slightly higher for CF than UF (1.17 vs. 1.14 SED 0.04) but not significant. CF wool had greater tensile strength, bulk and yellow but lower crimp frequency (all P<0.01) than UF wool. Selection for ultrafine wool in Merino sheep has shown FD was significantly reduced without negative effect on liveweight and reproduction.

T, Wuliji, KG Dodds, RN Andrews, and PR Turner

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 284-287, 1998