1. In a balance study with young chicks estimates of nitrogen retention were made by a balance method and by a body analysis method.
2. N retention appeared to be about 15% greater by the balance method when no allowance was made for N in alimentary tract contents. Allowance for tract contents reduced the difference to about 13%.
3. Only about one-third of the discrepancy could be accounted for interms of the possible sources of N loss investigated.
4. About a quarter of the difference was due to loss of N on drying the droppings before analysis and another tenth to loss of N on freeze-drying minced chick tissues.
5. No appreciable loss of ammonia could be detected from chickens and excreta under conditions prevailing in the balance trial. The efficiency of digestion of feathers, uric acid and droppings from birds appeared to be complete by the Kjeldahl method employed.
6. A difference of about 8% could therefore not be explained.