Development, structure and seasonal change in the fleeces of unimproved Scottish Blackface sheep from the Hebrides

Abstract

SUMMARYDetails are given of the fleece and other characteristics of three rams and three ewes of a strain that has lived feral on the island of Boreray in the St Kilda group since 1930.The animals are horned and short-tailed, the rams are about 60 cm high at the withers and weigh about 45 kg at maturity, while the ewes weigh between 25 and 30 kg and are 55 cm high. The ewes reached their maximum weight after 1 year, but the rams increased in weight during the 3 years under observation.The fleeces were shorter and finer than those of the modern Blackface, tending to have kemps rather than hairy heterotype fibres. The fleece weight was 1·25 kg, staple length ranged from 75 to 150 mm and mean fibre diameters ranged from 23 to 32 μm.Variable fleece casting occurred although no more than about 80% of both the primary and secondary follicles became inactive during the winter. Unlike other primitive breeds studied there was a relatively narrow peak of follicle inactivity in midwinter, although in the ewes this tended to occur later in the winter, as observed in improved breeds.There was a subsidiary small peak of follicle inactivity in August corresponding to the primitive shedding of the summer coat. Maximum fibre medullation occurred in June, and there was a second smaller peak in September.As in other primitive breeds a relatively high proportion of follicles lacked fibres at birth, but this retardation of development was no longer evident by 14 days when the usual peak in medullation occurred. More fibre shedding was observed at 56 days than in the modern Blackface. The fibre type arrays were of Plateau P1 type.