|Publication Type:||Journal Article|
|Year of Publication:||1999|
|Authors:||A. Darwish, Hennessy, D. R., Maxwell, C. A.|
|Journal:||Australian Veterinary Journal|
|Pagination:||667 - 670|
|Keywords:||body, Damalinia ovis, fractionation, louse, Phthiraptera, resistance, schrank, sheep, trichodectidae, wool|
Objective To measure the production and amount of oxidation of wool grease secreted immediately after shearing. To identify components of wool grease that might act as a carrier to facilitate lateral diffusion of topically applied insecticides. Design Fine-wool Merino sheep were shorn and residual greasy wool was collected from the sheep's flank. The quantity of grease produced, and the amount of oxidation was measured during 18 days after shearing. Wool grease was fractionated into five component groups based on their polarity and the degree of oxidation in these fractions determined. Results There was a 24% increase in grease production within 2 days after shearing but secretions returned to pre-shearing amounts after 4 days. During this period wool grease oxidised rapidly. Of the grease fractions examined, sterol and wax esters remained essentially unoxidised whereas free sterols such as cholesterol and lanosterol, fatty acids and polar lipids, aldehydes and alcohols were extensively oxidised within 7 days after shearing. Conclusion The transient increase in grease production after shearing may facilitate diffusion of topically applied synthetic pyrethroid insecticides. Oxidation of grease components may then contain the insecticide and limit further diffusion. Incorporating the insecticide in non-oxidising fractions of wool grease may make insecticide dispersion more efficient.