Merino birthcoat fibre types and their follicular origin

Abstract

The great majority of the fibre-type arrays from the backs of eighty Merino lambs were Plain (including Coarse Plain); Plateau and other arrays also occurred. In most samples no medulla could be seen in the pre-natal parts of halo-hairs examined in benzene, but the presence of medullary substance was demonstrated. All HH were shed and apparently replaced by fine fibres. The shape of the tip curls of early CT fibres in some samples altered with age, apparently by 'setting' in a line of yolk. HH grades ranged from I to VII and there were probable strain differences in grade and medullation. A total of 599 primary and 2595 secondary follicles and their fibres were identified by dissection. Primary follicles contained HH, SS, Sk, or early CT fibres, secondary follicles only CT or Hi. Sickle fibres commonly occupied most of the PL follicles except where the array was Plateau.