Abstract

Groups of 10 ewes of four breeds (Romney, Dorset cross Romney, Texel cross Romney, (Dorset x Romney) cross (Texel x Romney) born in two years (1994, 1995) were used to investigate the changes of wool characteristics with increasing age. Each ewe was wool sampled at hogget shearing in October and at each subsequent annual shearing in July until 1999. Romney fleeces had higher clean fleece weight, lower core bulk, longer staple length, less fibre curvature and lower crimp frequency. All genotypes exhibited similar ageing patterns for each measured wool characteristic except fibre diameter variability. Days to form a crimp increased, staple length and core bulk did not change and fibre curvature and crimp frequency decreased with increasing age. Clean fleece weight and fibre diameter increased to a plateau between 2 and 4 years of age before declining. The repeatability of all individual characteristics decreased with increasing age. There were no consistent differences in the relationship between core bulk and a combination of fibre curvature and fibre diameter across genotypes within age groups. Crossing Dorset and Texel rams over Romney ewes to generate a specialty high wool bulk composite genotype did not influence the age trends and interrelationships between individual wool characteristics inherent in the base Romney flock.

RMW, Sumner, and MP Upsdell

Proceedings of the New Zealand Society of Animal Production, Volume 61, Christchurch, 100-103, 2001