Mixture experiments: a severe test of the ability of a broiler chicken to make the right choice.

1. A mixture experiment was used to measure the biological performance (weight gain and food conversion efficiency) of broilers from 7 to 21 d of age when Fed 1 of 13 combinations of 3 protein sources. The objective was to determine the combination of ingredients that would maximise biological performance. 2. The experiment consisted of 2 diet series: in the 1st series, the 3 protein sources used were fishmeal, sunflower oilcake meal and soyabean oilcake meal, and in the 2nd, the soyabean oilcake meal was supplemented with DL-methionine. The combinations of 2 and 3-component mixtures that maximised performance in the 2 series were then compared with the selections made by chickens offered a choice of 2 or 3 components separately. 3. In all cases, the choices made by the broilers coincided with those mixtures that maximised performance. 4. It is clear from this experiment that broiler chickens will attempt to maximise performance by choosing the best possible combination of protein sources when given the opportunity to do so.