Previous Awassi grazing on a paddock or grazing in the same or adjoining paddock,does not cause fibre contamination of fleeces of Merino sheep

Abstract

The fleeces of Merino wethers grazed either in common or adjacent paddocks with Awassi rams were analysed for the presence of contaminant fibres (pigmented, urine-stained and kemp). In addition, the effect of previous grazing history of the paddock (i.e. whether or not that paddock had been previously grazed by Awassi sheep) on the level of fibre contamination was also investigated. Under extensive grazing conditions, very few Awassi contaminant fibres were transferred into the Merino fleeces. In fact, there was no significant difference between the control group, grazed outside the quarantine facility, and any of the treatment groups grazing within the quarantine area. The previous grazing history of the paddock had no effect on the number of contaminant fibres transferred, suggesting that even if contaminant fibres fall onto the paddock, they do not contaminate the fleeces of Merino sheep that subsequently graze that paddock. Upto 100% of the contaminant fibres transferred into the Merino fleeces were lost within 4 weeks after the removal of the Awassi rams from the paddocks. Therefore, withholding shearing of Merino sheep for 4weeks after any contact with Awassi sheep would be sufficient for the level of contaminant fibres in the greasy fleece to fall to below commercially acceptable limits for dark fibres in worsted processing.