Mineral and amino acid composition of wool from New Zealand Merino sheep differing in susceptibility to yellowing

Abstract

The susceptibility of wool to yellowing was determined on samples from fleeces of 36 Merino wethers by a laboratory procedure involving incubation at 40¦C for 5 days. The sheep, although originating from several different flocks, had been grazing together for 6 years. These susceptibilities were compared with the concentrations of suint and wax in the fleece, with fibre diameter, and with mineral concentrations in suint or yolk from the greasy wool. While the susceptibility of the fleeces was correlated with suint content (r = 0.852), the highest correlations were with the potassium concentrations in either suint before (r = 0.947) or yolk after (r = 0.938) incubation. There were significant differences in the concentration of potassium in the wool after washing, between the four most resistant and the four most susceptible fleeces, and in the effect of incubation on these potassium concentrations. No differences were detected in concentrations of other minerals in the clean wool nor in the relative proportions of amino acids.