Studies of the Energy Requirements of Chickens

COMPARATIVE studies of the efficiency of utilization of rations for egg production are made difficult by the well known fact that gross efficiency, measured as feed requirement per dozen eggs produced, is markedly affected by rate of production. Because of this relationship relatively small differences in egg production rate, which may be of limited or no significance in themselves, have the effect of masking or magnifying the respective differences between rations in efficiency of feed utilization. Bird and Whitson (1946) were the first to attempt to circumvent this difficulty by comparing the observed rate of feed consumption to that predicted by the Byerly (1941) partition equation on the basis of the observed rate of production, average body weight and weight gains. From the observed and predicted rates of feed consumption, an index of relative efficiency was calculated for each ration under study. Lillie and coworkers (1952), using a similar procedure, …