Post-natal follicle development and fleece changes in two selection lines of Scottish Blackface sheep

Abstract

SUMMARYFleece and skin samples were taken at intervals from birth to 86 days from Scottish Blackface lambs born into one line selected for hairiness, another for fineness and an unselected control line. The birthcoats in the Hairy line were longer than those in the Fine line, and had a predominance of Plateauo and Pi fibre type arrays, whereas P2 and P3 arrays predominated in the Fine line. The Hairy group had significantly more halo hairs and hairy-tip curly-tip fibres, but significantly fewer histerotrichs.Most secondary follicles had fibres by 56 days, and development appeared to be faster in the Control than in the other two groups. The Hairy and Control groups had consistently high percentages of primary medullation, whereas the Fine group had a peak at 14 days. The Fine group had consistently low secondary medullation, whereas it increased in the Hairy and Control lambs, apart from a set-back at 28 days.Up to 56 days the Fine group had no fibre shedding in the skin, and the Hairy group had most, although the incidence in any sample was less than 2%. There was more follicle inactivity at 86 days, and the Fine group then had most.