Genetic variation in sulfur, calcium, magnesium, manganese and trace metal content of Merino wool and correlations with brightness, yellowness and photostability

Genetic parameters (heritability, phenotypic and genetic correlations) were estimated for sulfur (S), calcium (Ca), magnesium (Mg), manganese (Mn) and trace metal content (i.e. Cu, copper; Fe, iron; Zn, zinc) of yearling (11 months, n = 387) and adult (23 months, n = 274) fleeces from the 2007 and 2008 cohorts of Merino progeny (including both ewes and wethers) born into the Sheep CRC Information Nucleus. There was significant genetic variation in S and all metals. Ninety percent of the variation in S and Zn content of yearling wool was genetic, while heritability estimates for the remaining metals were all higher than 0.28 except for Cu (h2 = 0.17 ± 0.11) and Mn (h2 = 0.03 ± 0.12) in yearling fleeces and Cu (h2 = 0.14 ± 0.18) in adult fleeces. Ca and Mg were very highly correlated both phenotypically (0.95 ± 0.01 as yearlings and adults) and genetically (0.95 ± 0.07 as yearlings). There were also strong genetic correlations between yearling and adult Ca and adult Mn (0.85 ± 0.22 and 0.88 ± 0.10), Mg and Mn (0.92 ± 0.10) and between yearling S and adult Zn (0.67 ± 0.22) and adult S and adult Zn (0.60 ± 0.22) suggesting similar genetic mechanisms controlling the biochemical pathways of incorporation of each pair of elements into the fibre. There were significant phenotypic correlations between certain elements and the brightness, yellowness and photostability of wool. Taken together across the yearling and adult measurements, the phenotypic and genetic correlations suggest that wool with higher concentrations of Ca and Mg would tend to be less bright, yellower and less photostable than wool with lower concentrations of these metals. Wool with higher concentrations of Mn would tend to have a similar impact to Ca and Mg on brightness, clean colour and photostability. Fe was also associated with less bright wool, however wool with a high Fe content would tend to be whiter but with a propensity to yellow following UVB exposure.