Growing pigs offered a choice of feeds differing in nutrient density (ideal protein and energy) may select a diet to meet individual requirements for optimum lean tissue growth rate. This has the potential for reducing the inefficiencies of nutrient under or over-supply associated with conventional single-diet feeding. The aim was to evaluate the scope for using the choice-feeding system in commercial growing and finishing pig production.

Seventy-two pigs were selected in 3 equal blocks at around 25 kg and housed in single-sex (gilts and boars) groups of six. They were offered least-cost formulated growing and finishing complete diets (Table 1) as a choice (C) from 25 to 95 kg or as in conventional single-diet (S) feeding in which a growing diet was fed from 25 to 50 kg and a finishing diet from 50 to 95 kg. Pigs were fed ad libitum and had unrestricted access to water. Pigs and residual feed were weighed weekly. Pigs were selected for slaughter in the week they approached 95 kg and measurements on chilled carcasses were made according to the method of Diestre and Kempster (1985).