Lamb consumption has fallen steadily over the past 40 years, partly due to the consumer's belief that it is an over-fat meat. In general, there are two approaches to solving this problem of excess fat. Firstly, to identify and breed from sheep that are genetically leaner. Secondly, to modify the feeding strategy to produce a leaner product. If an interaction between the genotype - either breeds or lines within breeds - and diet exists, establishing methods for linking selection and feeding programmes becomes a priority. In the first year of a programme investigating genotype by dietary interactions in sheep, the effect of non-limiting and limiting foods on growth rate, feed efficiency and body composition in ewe lambs from a line of Suffolk sheep was evaluated indoors.