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The concentration of gross energy in 24-h pooled samples of milk is compared with that of single samples obtained during the same period. Samples were collected from mothers exclusively breastfeeding their infants on demand. The objective of the comparison was to evaluate simplified sampling schemes for approximating the concentration of energy of milk produced over 24 h. The lowest concentration of energy of single samples occurred in milk collected between 12 midnight and 6 a.m. The concentration of energy of milk was related negatively to the volume expressed and the time interval preceding each expression. The interval preceding each expression was correlated positively to the volume expressed. These results indicate that the pattern of milk expression is important in the design of sampling schemes. Therefore, sampling schemes may not be transferable between populations with distinct feeding patterns. The highest correlation between single samples and the 24-h value was obtained from samples collected between 12 midnight and 6 a.m. (r= 0.84, p < 0.001). The widths of the 95 confidence and prediction intervals for the equation relating values from single samples to the 24-h pools were ± 2.7 and ± 10.5, respectively, of the mean 24-h pool sample value when three single samples (collected between 12 midnight and 6 a.m., 6 a.m. and 12 noon, and 6 p.m. and 12 midnight) were included in the predictive equation.

The macronutrient, trace mineral, and immunological contents of milk of five moderately controlled, insulin-dependent diabetic women were studied at 3 months postpartum. Concentrations of total nitrogen, lactose, fat, and energy were not distinguishable from those in milk of nondiabetic women. Glucose concentrations in milk from diabetic women were significantly higher (p 0.001) and more variable. The macro- and trace minerals (Ca. P. Mg. K. Zn. Cu. and He) were within normal ranges with the exception of Na which was higher in milk from the diabetic women (p 0.05). The concentrations of lactoferrin and secretory IgA were not statistically different from reference norms. Milk composition of five insulin-dependent diabetic women was not distinguishable from that of the reference population, with the exceptions of Na and glucose concentrations, which were slightly elevated.

Colonic fermentation of unabsorbed lactose was evaluated by measuring breath hydrogen BH2after a regular feeding in 17 white, normal, exclusively breastfed infants 45 weeks of age. Interval breath samples were collected with a specially modified face mask and analyzed by gas chromatography for H2and CO2concentrations. Five infants 29 produced 20 ppm or more of H2, four of whom underwent repeated testing. Three infants stopped producing over 20 ppm of H2as they grew older. On a repeat evaluation, one of these three infants had levels over 20 ppm when other foods were introduced into his diet. The other continued to have elevated BH2when weaned. Stools of infants with elevated BH2levels had no detectable glucose, and pH was over 5.5. Weightforage of infants with elevated BH2was at or above the 75th percentile. BH2levels, normalized for the amount of breast milk ingested, fell significantly with age. These results show that complete small bowel absorption of lactose from breast milk does not occur in all white, normal, term, appropriateforgestationalage infants in the first months of life. The absence of glucose in the stool and the normal stool pH suggest that the unabsorbed lactose that produced H2can be degraded in the colon.

Summary: This study was designed to estimate energy intake in exclusively formula-fed infants. Formula intake of twenty-four 1− and 4-month-old infants was studied for 5 consecutive days; six boys and six girls were in each age group. Intake was estimated by laboratory-determined weights of formula consumed, spilled, and regurgitated. Two additional methods were used to estimate intake in the first nine infants during the 1st day of observation: test-weighing the infant at each feeding and mother's weighing of formula consumed, regurgitated, and spilled at each feeding. No consistent differences were detected among methods, but test-weighing appeared to have the greatest feed-to-feed variability. Intake was estimated to be 747 ± 100 g or 125.5 ± 17 kcal/kg, and 958 ± 131 g or 94.0 ± 13 kcal/kg for 1− and 4-month-old infants, respectively. The day-to-day variability (expressed as the coefficient of variation) was 13 and 15 (CV, g/kg) for 1− and 4-month-old infants, respectively. Between-infant variability of intake was ∼8 (CV, g/kg) for both age groups. Energy intakes of 1-month-old formula-fed infants were similar to published values of breast-fed infants of similar age, but the energy intakes of 4-month-old formula-fed infants were significantly higher than values published for 4-month-old breast-fed infants.

Heart rates of 46 breast-fed and formula-fed infants were monitored continuously for −18 h at 1 or 4 months of age. Heart rate differed significantly by age (1 month > 4 months; p < 0.001) and feeding mode (breastfed < formula-fed; p < 0.001). Approximately 58 of the variability in heart rate could be attributed to feeding mode, sex, and age. Heart rate was correlated significantly with energy intake (r = 0.60; p < 0.001), but not sleeping metabolic rate or total daily energy expenditure. Energy intake accounted for none of the variability in heart rate beyond that explained by feeding mode, sex, and age.