Mating Awassi rams to Merino ewes causes an initial level of fibre contamination which decreases to an insignificant level eight weeks post-mating

The fleeces of Merino ewes mated by Awassi rams were analysed for the prese nce of contaminant fibres (pigmented, urine-stained and kemp). In a control led shed mating, high numbers of contaminant fibres were found in the fleec es of the ewes, with the number of fibres transferred being proportional to the number of times the ram mounted the ewe. The number of fibres transfer red during the shed mating were substantially higher than those found after paddock mating. In the latter instance, environmental conditions and conta ct with other sheep would have contributed to the loss of fibres from the r ecipients' fleeces. Each ram breed used in the paddock mating experiment, M erino, Awassi and Suffolk, transferred fibres into the fleeces of the mated ewes. The Suffolk transferred relatively more fibres than both the Awassi or the Merino rams, in addition the fibres from the Suffolk were significan tly darker than those from the other breeds thus compounding the severity o f the contamination. Both mating experiments demonstrated that the number o f contaminant fibres remaining in the ewe's fleece 8 weeks after mating was not different to that existing in the fleece of the ewes before mating. Th erefore, in commercial flocks, the risk of contamination can be minimised b y shearing breeding ewes 8 weeks after rams have been removed from the bree ding flocks.