Wool follicle and skin characters - Their potential to improve wool production and quality in Merino sheep

Abstract

This paper investigates the relationships between objectively assessed skin and follicle characters, and objectively measured fleece characters, in the South Australian Strongwool Merino strain. The relationships between objectively-assessed skin characters and classer assessed skin and staple characters were also investigated. The results of these and other studies indicate that genetically high producing sheep with low fibre diameter, tend to be those with high follicle density, high secondary/ primary follicle ratio, evenly-seated follicles arranged in distinct, large follicle groups. The follicles of these sheep tend to have a low degree of curvature and produce fibres with low crimp frequency, low paracortex content, low sulphur content, but with well-defined crimp. Somewhat surprisingly, we found that sheep with light (thin?) skins tended to produce more wool of lower diameter than heavy (thick?) skinned animals. This is in direct contrast to previous findings of moderate positive genetic correlations between skin thickness and both fleece weight and fibre diameter. Skin quality, subjectively assessed by a classer, had a moderate to high heritability (0.36 and 0.24 at 10 and 16 months of age, respectively) and was closely genetically associated with clean fleece weight (rg = 0.65 and 0.57 at 10 and 16 months of age, respectively). As such, skin quality could be a useful indirect indicator of fleece weight. It also means that selection for clean fleece weight should result in an improvement in skin quality. The latter is contrary to the belief of some in the industry, that selection for fleece weight will result in a deterioration in skin quality. It is recognised that a number of skin characters (objectively and subjectively assessed) are associated with economically important wool traits. However, it is doubtful that an increased (or sole) emphasis on them will bring about rates of genetic gain greater than what can be achieved by direct measurement of, and selection for, the economic traits in question. It is recognised that a number of skin characters (objectively and subjectively assessed) are associated with economically important wool traits. However, it is doubtful that an increased (or sole) emphasis on them will bring about rates of genetic gain greater than what can be achieved by direct measurement of, and selection for, the economic traits in question.