Abstract
1. Calorimetric measurements were made on 5‐week‐old male chickens sampled from the third generation of three lines selected for either increased live‐weight gain (W), food consumption (F), or food conversion efficiency (E). A control line (C) was also measured. 2. Food intake and food conversion ratio were greater (PP(P < 0.05) in the F than the other lines. 6. Availability of ME (net energy) was the same (85%) for all lines but calculated daily maintenance energy requirements (kJ ME/kgW) were W, 860; F, 937; E, 796 and C, 810. 7. By 9 weeks the F line contained more fat and less water than lines E and C.