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close this bookProtein-Energy Requirements of Developing Countries: Evaluation of New Data (UNU, 1981, 268 pages)
close this folderObligatory and integumental nitrogen losses - children
Open this folder and view contentsObligatory nitrogen losses and factorial calculations of protein requirements of pre-school children
Open this folder and view contentsIntegumental nitrogen losses of pre-school children with different levels and sources of dietary protein intake
View the documentThe protein requirements of normal infants at the age of about one year: maintenance nitrogen requirements and obligatory nitrogen losses

The protein requirements of normal infants at the age of about one year: maintenance nitrogen requirements and obligatory nitrogen losses

P.C. Huang, C.P. Lin, and J.Y. Hsu
College of Medicine, Taiwan University, Taipei, Taiwan

Abstract from the Journal of Nutrition*

With 34 normal, healthy male infants aged 9 to 1 7 months, a total of 61 nitrogen (N) balance studies were conducted with N intake between 12 and 180 mg/kg/day. By regression analysis, the crude N maintenance requirements, either with whole egg or cow's milk protein, were estimated to be about the same, 106 and 103 mg/kg/day, respectively. The 97.5 per cent confidence limits for the requirements were 128 (egg) and 142 (milk) mg/kg, respectively. Sums of the obligatory urinary and faecal N for the egg and milk protein series were 75 and 71 mg/kg compared with 76 mg/kg of the actually measured figure. Ratio of the maintenance N requirement to the obligatory N loss was 1.4. In another 15 N balance studies, for which N intake from milk formulae ranged between 220 and 320 mg/kg/day, the mean apparent N retention was 25% of the intake. Total integumental N losses (skin + hair + nail) of infants fed 217 to 522 mg N/kg/day amounted to 7.9 ± 2.9 mg/kg daily. Egg protein had somewhat higher digestibility than cow's milk protein, 92 versus 87%, but a lower biological value, 76 versus 82. Net protein utilization (NPU) estimated from the regression line was about the same for both proteins, 71 and 69, respectively.



FIG. 1. Nitrogen Retention by Male infants 9 to 17 Months of Age at Various Levels of Egg Protein Intake.

The regression lines were drawn as follows: The regression equation for line UU' (-- ), for those whose nitrogen intake was less than 63 mg/kg/day, is Y = 0.578X - 71.85 (n = 11, r = 0.86, p < 0.01) where X = nitrogen intake and Y = nitrogen retention in mg/kg/day. The regression equation for line MM' (- - ), for those whose nitrogen intake was more than 70 mg/kg/day, is Y = 0.664X-69.40 (n = 18, r = 0.85, p < 0.01). Line R R' ( ) was plotted against all information; its regression equation is Y = 0.706X 75.11 (n = 29, r = 0.97, p <0.01).



FIG. 2. Nitrogen Retention by Male Infants 9 to 17 Months of Age at Various Levels of Milk Protein Intake