The degree of penetration of advances in nutritional research to the benefit of the pig producer is of considerable concern to both scientists and advisers. In formulating the nutritional policy for his pig enterprise, the farmer relies heavily on the advice which he receives from either national or commercial advisory services, and on his own first-hand experience. There may be other influences affecting his decisions, such as the reputation of a particular product or company, but apart from these it is rare to find farmers who have made a really serious objective attempt to evaluate their whole feeding programme. Recent developments in the economic climate have produced a situation in which profit margins for compounders and producers have reached critical levels; this, combined with world shortages of ‘safe’ protein concentrates such as fish meal, has provided a stimulus for the reassessment of established practices and loyalties. The purpose of this paper is to examine some of the ways which are open to the farmer or his adviser for evaluating in an objective way the possible consequences of changing from one diet or feeding practice to another.