Differences in sheep management and breeding programmes lead to variations in carcass fatness. It is necessary to investigate the relationships between breed, growth and composition on different feeds in order that leaner carcasses may be produced. The purpose of this experiment was to investigate these relationships in two breeds of sheep, and their cross, when fed either a food considered non-limiting to growth or a food that was restrictive by virtue of its bulk.

Suffolk (S), Scottish Blackface (B) and reciprocal cross (X) lambs were born over a 4 week period beginning late February. The lambs were weaned at a weight (0.20 estimated mature size) or no later than 8 weeks of age and following an adjustment period, individually penned.