The potential use of skin-based selection criteria in Merino breeding programs: a review of research, with reference to the soft rolling skin concept

A review was conducted of recent published research investigating (1) the f ollicle attributes of various Merino skin types, including the soft rolling skin type, and (2) the potential use of skin-based traits as within-flock selection criteria. A number of comparative studies of different Merino skin types, when viewed together, did not demonstrate any consistent associations between skin typ e and each of follicle density, S/P ratio and traits associated with wool q uantity and quality. All skin-based characteristics, including traditionall y-assessed skin quality and soft rolling skin assessment, have been shown t o be under low to moderate genetic control. A number of favourable genetic correlations are reported between skin-based characteristics (including tra ditionally-assessed skin quality) and traits relating to wool production an d quality. However, no estimates of genetic correlations involving soft rol ling skin assessment are available to date. The potential value of using sk in-based selection criteria for within-flock selection is shown to be incon clusive. Of particular importance is the potential for the same "approach" to deliver different outcomes when applied to different breeding objectives and Merino strains. It is concluded that there is insufficient experimental evidence to support any broad sweeping statements made either in favour of or in opposition to the potential value of skin-based assessment.