Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Quantitative genetic studies on wool yellowing in Corriedale sheep. 1. Wool yellowing susceptibility and wool production traits-genetic parameter estimates.

Abstract

During 1989-92, data were collected from 1492 progeny of 53 sires from a Corriedale sire progeny test flock from Canterbury, New Zealand. Genetic parameters were estimated using restricted maximum likelihood procedures using an average information algorithm. Estimated heritability for wool yellowing susceptibility was 0.27±0.06. Genetic correlations between wool yellowing susceptibility and greasy fleece weight, clean fleece weight, yield percentage, mean fibre diameter and subjective greasy wool colour assessment were 0.20±0.14, 0.11±0.14, -0.15±0.13, 0.24±0.14 and 0.95±0.06 respectively. Phenotypic correlations were low. Colour score had a heritability of 0.30±0.06 and medium-high genetic correlations with all traits, except clean fleece weight. Heritability estimates of greasy fleece weight, clean fleece weight, yield and fibre diameter were 0.55±0.07, 0.52±0.07, 0.51±0.07 and 0.52±0.07 respectively. Responses in yellowing susceptibility are predicted to be higher when selection is on wool colour (-0.21 score/year) than when selection is on yellowing susceptibility itself (-0.19 score/year). A selection index, including clean fleece weight (CFW), mean fibre diameter (MFD) and yellowing susceptibility (YPC) as aggregate breeding and breeding objective traits (I = 3.26CFW - 0.14MFD + 0.03YPC) predicted an increase in yellowing susceptibility.