Abstract

Propensity of wool to yellow is defined as its yellowness after incubation for 14 days at 40 C and 100% relative humidity. It was determined for mid-side wool samples from Romney, Coopworth and Perendale ewes shorn in summer and/or winter. All samples had a high propensity to yellow (mean Y-Z after challenge 13.0 SD 3.2). The breed ranking from lowest to highest was Perendale, Romney and Coopworth (12.4, 13.1, 13.6, respectively; SED 0.2). Wool shorn in winter was less susceptible to yellowing than wool shorn in summer (11.7 vs 14.4; SED 0.26) and short wool was less susceptible than long wool (12.0 vs 14.1; SED 0.26). There was a highly significant interaction between wool length and time of shearing. Propensity to yellow of wool sampled at hogget shearing was not a significant predictor of propensity to yellow of the adult fleece wool. The measurement was repeatable between some, but not all, successive shearings of adult ewes. This suggests that the method used may be useful in selecting adults to reduce yellowness by breeding.

TC, Reid, RMW Sumner, JR Sedcole, and KJ Botica

Proceedings of the New Zealand Society of Animal Production, Volume 56, , 324-327, 1996