### Summary of the main results

**1. Obligatory Nitrogen Losses**

The results are summarized
in table 1 and figure 1. The mean and S.D. for the combined data of days five to
nine were 34.0 5.3, 19.5 6.9, and 53.7 8.1 mg N/ kg/day for urinary,
faecal, and both urinary and faecal nitrogen, respectively.

If the study had been done in only six days and the mean values of days five
and six used, the corresponding results would have been 33.2 5.9, 19.9 6.8,
and 53.0 7.7 mg N/kg/day for urinary, faecal, and both urinary and faecal
nitrogen, respectively.

**2. Factorial Calculations **

Assuming that integumental
nitrogen losses were of the order of 5 mg N/kg/day on a protein-free diet, total
obligatory nitrogen losses would be 59 mg/kg/day, or 40 per cent less than the
current FAD/WHO estimates. Adding 15 mg N/kg/day for growth of children of the
same height-age and multiplying by 1.3, as suggested by FAD/WHO (WHO Tech. Rep.
Ser. No. 522, 1973), results in an estimated mean requirement of 96.2 mg
N/kg/day, equivalent to 0.60 9 of milk or egg protein/kg/day. This value
coincides with the mean requirement of 0.61 g/kg/day calculated by us using
multiple-level nitrogen balance techniques (see summary of study by Torabrera Santiago, and Viteri, this
volume).