Note on the effects of protein concentration on responses to dietary lysine by chicks.

1. This paper gives further analyses of data from previously reported trials in which chicks were fed diets with protein concentrations ranging from 140 to 280 g/kg diet, with the lysine content varied at each protein concentration. 2. Alternative methods of estimating the lysine requirement, at each concentration of protein, are investigated. 3. Although these methods produce rather different estimates of requirement, they do not change the conclusion that the lysine needed for maximum growth or maximum efficiency of food utilisation is a linear function of dietary protein concentration throughout the range from 140 to 280 g crude protein/kg. 4. It is concluded that lysine requirements for growing chicks should be specified as a proportion of the protein and not as a proportion of the diet.