25—CROSS-BREEDING STUDIES WITH SELECTED FLEECE LINES OF SCOTTISH BLACKFACE SHEEP

Abstract

This paper presents the results of an investigation of the fleeces of sheep that were the offspring of crosses (HF) between a hairy line (HH) of the Scottish Blackface breed that had been selected for 20 years for hairiness and a fine line (FF) that had been selected for fine fleeces. Other crosses investigated were between each of the selected lines and an unselected Control (CC) line (HC and FC), and with the Wensleydale breed (WH and WF). The lines had been selectively bred on an index of wool-fibre medullation determined from an eight-week-lamb coat sample, and there was some evidence of heterosis in the index of HC lambs, the values being closer to the value in hairy lambs than the mid-parent value. Fibre-type array (FTA) determined at the same age showed that HC and HF animals were more hairy than Controls, while FC lambs had finer arrays. The Wensleydale-cross lambs had considerably reduced hair coverage and lower hair densities than the Blackface, and FTAs showed a shift from the 100% Plateau arra...