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Energy intake recommendations for infants are based on data from industrialized countries. FAO/WHO/UNU expressed the need for studies on total energy expenditure (TEE) and basal metabolic rate from developing countries covering current and changing lifestyles. For this observational study, 65 infants of differing socioeconomic status (SES) (n = 32 middle SES, n = 33 low SES) were selected in Pelotas, southern Brazil, aiming to: 1) compare TEE, minimum observable energy expenditure (MOEE), activity energy expenditure (AEE) between breast-fed infants 8.7 mo of age from middle and low SES; and 2) investigate the effect of potential mediating factors on TEE and AEE. TEE and total body water were measured with doubly labeled water, MOEE with respiration calorimetry, breast milk intake using the dose-to-the-mother deuterium-oxide turnover method, food intake using 1-d food weighing, and prevalence of overweight using BMI Z-scores. TEE adjusted for ethnicity was 257 (95% CI 232-281) kJ/(kg * d) in middle SES infants vs. 318 (95% CI 294-342) kJ/(kg, d) in low SES infants (P 0.001). MOEE did not differ between groups and the difference in TEE was therefore attributed to AEE (P = 0.008). The effect of SES on AEE was mediated by the number of persons per bedroom (crowding). Prevalence of overweight tended to be higher in middle SES infants (P = 0.054) than in low SES infants. The difference in TEE and AEE between SES groups emphasizes the importance of an accurate description of the SES of any population in which TEE is studied and questions the extent to which TEE data from middle-class infants in transitional countries should be considered normative.

Although it is widely accepted that energy expenditure in infants is a function of feeding pattern, the mechanism behind this is not well understood. The objectives of this observational study were as follows: 1) to compare minimal observable energy expenditure (MOEE) between 2 subgroups of breast-fed infants, a BM group in which breast milk was the only source of milk and a BCM group given cow's milk in addition to breast milk; and 2) to identify potential mediators of a feeding pattern effect. For this purpose, infants were classified by feeding group on the basis of a mother's recall. Respiration calorimetry was used to measure MOEE in 62 infants (n = 35 BM, n = 27 BCM) aged 8.7 mo in Pelotas, southern Brazil. Breast-milk intake was measured using deuterium oxide, complementary food intake by 1-d food weighing, total energy expenditure and total body water using doubly labeled water; anthropometric indices were calculated. MOEE was 1672 [+ or -] 175 kJ/d in BM compared with 1858 [+ or -] 210 kJ/d in BCM infants (P < 0.001). Mass-specific MOEE was 201 [+ or -] 24.6 and 216 [+ or -] 31.9 kJ/(kg * d) in BM and BCM infants, respectively (P = 0.041). MOEE (kJ/d) was mediated by protein intake and fat-free mass ([R.sup.2] = 41.4%). We conclude that complementary feeding with cow's milk alters the sleeping metabolic rate in breast-fed infants. These findings deserve attention in relation to 'metabolic programming' and the development of obesity later in life. J. Nutr. 135: 1889-1895, 2005. KEY WORDS: * minimal observable energy expenditure * sleeping metabolic rate * breast milk * cow's milk * infants

Ileal endogenous nitrogen recovery (ENR) in pigs (9 [+ or -] 0.6 kg body weight) was estimated simultaneously using the [sup.15]N-isotope dilution technique ([sup.15]N-IDT) and the peptide alimentation ultrafiltration (UF) method. Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. The amino acid (AA) pattern of the ENR was also determined. The ENR of pigs fed the quebracho diet was higher (P = 0.0001) than that of pigs fed the control diet [6.00 vs. 1.95 g/kg dry matter intake (DMI) for the [sup.15]N-IDT and 5.18 vs. 1.49 g/kg DMI for the UF method, respectively]. With the [sup.15]N-IDT, ENR values were 0.44-0.79 g/kg DMI (24%) higher (control P = 0.0032, quebracho P = 0.0002) than for the UF method. Apparent nitrogen digestibility depended on diet (69.0% quebracho vs. 86.0% control, P = 0.0001). Real nitrogen digestibility (RD-N) determined by the UF method was higher (P = 0.0001) for the control than for the quebracho diet (91.4 vs. 88.2%). Corresponding values for the [sup.15]N-IDT did not differ (P = 0.0569) between diets (92.8 vs. 91.4%). The [sup.15]N-IDT gave higher values for RD-N of both diets (control P = 0.0030, quebracho P = 0.0002) compared with the UF method. Endogenous AA recoveries (g/kg DMI) were increased 300% (P = 0.0001) and the AA-pattern of ENR was changed (P from 0.0001 to 0.7530 for different AA) by the quebracho diet. A constant AA-pattern of ENR cannot be assumed. Despite limitations of both techniques, the [sup.15]N-IDT and the UF method gave similar results with respect to ENR. J. Nutr. 134: 3076-3082, 2004. KEY WORDS: * quebracho extract * [sup.15]N-isotope dilution technique * peptide alimentation ultrafiltration * endogenous amino acids * condensed tannin

The [sup.15]N-isotope dilution technique ([sup.15]N-IDT), with either pulse-dose oral administration or continuous i.v. administration of [[sup.15]N]-L-leucine (carotid artery), both at 5 mg/(kg body weight, d), was used to measure ileal (postvalve T-cecum cannuia) endogenous nitrogen recovery (ENR) in pigs (9 [+ or -] 0.6 kg). Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. Blood was sampled from a catheter in the external jugular vein. Mean plasma [sup.15]N-enrichment at d 8-10 was higher (P = 0.0009) after i.v. than after oral administration [0.0356 vs. 0.0379 atom% excess (APE)]. Plasma [sup.15]N-enrichment for i.v. infused pigs was 0.01117 APE higher (P < 0.0001) and for orally dosed pigs 0.0081 APE lower (P < 0.0001) at 11 h postprandial compared with 1 h postprandial. Apparent ileal N digestibility was higher (P < 0.0001) for the control (85.5%) than for the quebracho diet (69.5%). ENR was calculated from the ratio of [sup.15]N-enrichment of plasma and digesta. The ENR for the quebracho diet was ~300% higher than for the control diet (6.03 vs. 1.94 g/kg dry matter intake, P < 0.001). The real N digestibility (92.2 [+ or -] 0.4%) was equal for both diets (P = 0.1030) and both tracer methods (P = 0.9730). We concluded that oral administration of [[sup.15]N]leucine provides reasonable estimates of ENR in pigs fed semipurified diets with high or low content of tannins; however, one must be careful in extrapolating this conclusion to studies with other protein sources or feeding frequencies. J. Nutr. 134: 3068-3075, 2004. KEY WORDS: * [sup.15]N-isotope dilution technique * oral label administration * first-pass uptake * endogenous N * quebracho tannin