Skin histology and birthcoat fibre-follicle relationships in Merino and ⅝ Merino lambs

Abstract

SUMMARYSkin biopsy samples from imported Merino and ⅝ Merino/⅜ Barki were examined from birth to the age of 1 year. Birthcoat fibre type arrays and fibre-follicle relationships were also studied.Merino lambs had a greater S/P ratio than ⅝ Merino at all ages; values at 1 year of age were 9·98 and 6·87 respectively.The ⅝ Merino lambs showed a wider range of follicle diameters than Merinos from birth to 1 year of age.The ratio of primary to secondary follicle diameters showed higher values in ⅝ Merino than in Merinos. Merino gave lower values of follicle wall thickness than ⅝ Merino.In Merino birthcoat samples, only one array was plain, representing 4%, whereas the rest were saddle. In ⅝ Merino the majority of fibre type arrays were plain, representing 75 %, whereas the rest were saddle and plateau.In Merino, because of the absence of halo hairs and super sickles, only two samples had few super sickle B; primary central follicles were occupied by sickle fibres, medium with large sickle ends as well as curly tips, and primary lateral follicles had mostly medium and fine curly tips, only four samples had sickle fibres, and secondary follicles produced medium and fine curly tips and histerotrichs.In ⅝ Merino primary central follicles produced halo hairs, super sickle A, A', B and occasionally sickle fibres, primary lateral follicles grew super sickle A, A', B, sickle fibres and curly tip fibres, and secondary follicles had medium and fine curly tips and histerotrichs.