1. The efficiency of food conversion by pullets and yearlings fed on high- and low-energy diets has been determined.2. Egg production was slightly higher by birds fed the low-energy diet for both pullets and yearling hens; pullets laid more eggs than yearling hens.3. For each age, the gross food intake was greater for birds fed the low-energy diet; the consumptions of digestible protein, non-protein digestible energy and metabolizable energy were the same for both diets and both ages of bird.4. The food cost per dozen eggs was slightly greater in the yearling year when the cost of rearing the pullets was ignored, and about the same when it was included.5. The efficiency of utilization of digestible energy and protein showed only a slight decrease from the pullet to the yearling year.6. The variation in the composition and digestibility of eighteen consecutive mixes of the highenergy diet and twenty-five of the low-energy diet was: crude protein 2%, non-protein digestible energy 5% and metabolizable energy 0·4 kg. cal./g. The digestibility of the crude protein and oil was 87%, for both diets; carbohydrates were 81% digestible in the high-energy diet and 59% in the low-energy diet.
