CEREAL FEEDING AND ITS IMPACT ON THE NITROGEN ECONOMY OF THE INFANT

To quantify the effect of rice cereal on nitrogen balance and fecal ni trogen excretion, and the contribution of endogenous nitrogen sources to fecal nitrogen output; nine infants aged 3-5 mo received [N-15]glyc ine in all feedings. Samples of urine and feces were obtained daily an d analyzed for nitrogen and N-15. On days 1-7 the infants received onl y formula, and a complete urine and fecal collection was made on days 6-7. From days 8 to 12 the formula was supplemented with rice cereal ( 133.3 g/L, or 4 g/30 mL formula) and a second complete urine and fecal collection was made on days 11-12. Cereal did not alter fecal nitroge n output or the calculated contribution (45%) of endogenous nitrogen t o fecal nitrogen. Cereal did increase nitrogen retention and lower the urinary excretion of the N-15 dose (24% of dose). The calculated true digestibility of the rice cereal protein was > 95%. Our results indic ate that infants aged 4 mo, in contrast with younger infants, are able to digest and absorb cereal. The addition of cereal to the diet does not lead to increased fecal protein losses.