Age effects and interrelationships between wool characteristics
of genotypes used to develop GrowBulk sheep
R.M.W. SUMNER AND M.P. UPSDELL
AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton,
New Zealand
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Proceedings of the New Zealand Society of Animal Production 2001. 61:
100-103
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.
Keywords: NZSAPAB;
wool bulk; age; fibre characteristics; Romney; Dorset; Texel
Last Updated 7/08/01
