EFFECT OF SELECTION FOR WOOL GROWTH ON SEASONAL PATTERNS OF YIELD, FIBER DIAMETER, AND COLOR IN ROMNEY LINES

Seasonal wool growth and associated wool characteristics were measured in a Romney line selected for high fleece weight and an unselected co ntrol line in 1990 and 1991. Both had a significant (P<0.01) decline i n wool growth rate in winter compared with summer. The wool growth rat e advantage (P<0.001) of the selected line over the control averaged 1 9 and 33% for ewes, and 24 and 36% for hoggets, in summer and winter, respectively. Staple strength, yield, and fibre diameter differences w ere closely associated with wool growth. Colour analysis showed no dif ference between lines in either brightness (Y) or yellowness (Y - Z). However, both the Y and Z values were lower in spring and summer, whil e Y - Z was highest in summer. The results suggest that selection for high fleece weight also improves major wool characteristics and reduce s the relative winter wool growth decline in Romneys.