Chemical changes in the wool wax of adult Merino sheep during prolonged wetting and prior to development of fleece rot

Abstract

Exposure of Merino sheep to artificial rainfall (25 mm/day for 2 and 5 days or 26.7 mm/day for up to 14 days) brought about a significant loss of wool wax from the fleece. The wax remaining in the fleece after wetting was altered in its chemical composition. The proportion of the wax that dissolved in methanol had increased and an increase in the free sterol content (cholesterol, lanosterol, dihydrolanosterol and a component with the chromatographic mobility of desmosterol and lathosterol) was observed. The origin of the increased free sterol content was probably hydrolysis by bacterial enzymes but there was no parallel increase in the free fatty acid level; possible reasons for this are discussed. It is suggested that the loss of wax and decreased hydrophobic properties of the wax remaining after wetting are factors assisting the penetration of the fleece by rain and the subsequent development of fleece rot.