Retentions of nirogen and minerals by babies 1 week old

Nearly 90 years ago, Bunge (1874) suggested that the composition of milk is adapted to the growth of the young of each particular species.Thus, the composition of cow's milk is suited to the needs of the calf, which doubles its birth weight in 6 weeks.It might be expected, therefore, that the human baby fed on cow's milk would gain weight more rapidly than the baby having its own mother's milk.In a recent review of the literature Aitken & Hytten (1960) commented on the difficulties of making a fair comparison between the weight gains of breast-fed and artificially fed babies.The influence of other factors such as the supply of breast milk, the calorific value of the various cow's-milk preparations and the hygienic conditions have to be taken into account.Many preparations made from whole or evaporated cow's milk with added sugar, particularly those used in America 1-30 years ago, provided more calories per IOO ml than breast milk, and there is evidence that babies having these milk mixtures were heavier than babies of the same age receiving breast milk (Nelson, 1930; Gordon & Levine, 1944; Frost &Jackson, 195 I ) .Present-day milk mixtures commonly used in Britain are prepared from dried whole cow's milk with the addition of lactose or other sugar, and when reconstituted according to the manufacturers' instructions, have calorific values almost the same as breast milk.The weight gains of breast-fed babies and those receiving such cow's-milk preparations have recently been shown to be essentially the same during the first 3 months after birth (Levin, Mackay, Neill, Oberholzer & Whitehead, 1959).The proportions of nitrogen and most minerals are greater in reconstituted COW'Smilk mixtures than in breast milk, so if similar volumes of milk are taken, babies receiving cow's-milk preparations will necessarily ingest more of these constituents than breast-fed babies.The retention of N by babies during the 1st year of life has been studied by many workers including Nelson (1930), Rominger & Meyer (I93I), Jeans & Stearns (1933) and Fomon & May (1958), and there seems to be no doubt that an increased intake results in an increased retention of N, and the same is true for the retention of mineral constituents (Rominger & Meyer, 1927;Jeans & Stearns, 1933; Stearns, 1939).Some of these studies were continued until the children were a year old, but none covers the early postnatal period.Fomon & May (1958) studied the N retention of four babies under 2 weeks of age, but no data concerning the mineral retentions of newborn babies receiving only breast milk or a cow's-milk preparation have been found in the literature.In rapidly growing newborn animals such as the piglet and the puppy, more than 6-2https://doi.org/10.