Performance of different Scottish Blackface stocks and their crosses

Abstract

SUMMARYThe performance of different stocks of Scottish Blackface sheep and their crosses was compared on a harsh Scottish hill experimental farm. The strains were the Stanhope farm stock (a control flock, closed for 30 years), stock from local Breeders, and first crosses and back-crosses of Stanhope stock with stocks represented by rams purchased at Lanark market. Some 3892 ewe records were available with 1837 lamb performance records. Estimated effects for the three types of stock and of heterosis in the Stanhope and Lanark cross were derived statistically. The local Breeders' stock had the heaviest lambs at weaning and the Stanhope stock the lightest. The local Breeders' stock also had the heaviest ewes and higher litter size but had lower fertility and lower lamb survival. Output expressed relative to ewe weight was highest for the cross-bred stock. Heterosis was positive for all traits studied except survival but was statistically significant only for ewe weight and lamb birth weight. If the Stanhope stock was representative of Scottish Blackface sheep of 30 years ago, breeding by Scottish Blackface breeders has led to an estimated improvement of 9% in the output per ewe exposed, and 5% in efficiency of production.