Factors asociated with yellowing within Romney fleeces
R.M.W. SUMNER
AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton,
New Zealand.
NZSAP 2002 Abstract No. 17
Proceedings of the New Zealand Society of Animal Production 62:
61-64
Four two-year-old Romney ewes born in the Waikato and four
two-year-old Romney ewes born in Canterbury that had been grazed
together in the Waikato for 12 months, were used to investigate aspects
of yellowing in wool samples grown on the mid-back, mid-side and
mid-belly. Two sheep in each sub-group had a history of having a
relatively high and two sheep a relatively low, propensity for their
fleece to turn yellow during the previous year. Dimensional fibre
characteristics, with the exception of staple length, were not
significantly different between body sites, between the propensity
groups or between birth farm groups. Wool was shorter on the belly than
on the other two sites. Incubating greasy sub-samples of each fleece at
40°C and 100% relative humidity for 6 d induced a curvilinear
increase in yellowness with the CIE Y - Z value approaching an
asymptote. A significant amount of the variation in yellowing was
explained by the concentration of K, Ca and possibly Na, elements
secreted in the suint. These data suggest that the propensity of a
fleece to turn yellow is not related to fleece architecture or the
elemental composition of the fibres, but may have a physiological basis
possibly related to sweating behaviour.
Keywords: NZSAPAB;
wool; Romney; yellowing; body site; elemental composition
Last Updated 30/07/2002
