Double metabolic balances on low birthweight infants fed formulae of differing composition.

The comparative nutritional merits of two infant milk formulae, Ready-to-Feed Premium Babyfood (Cow and Gate Ltd.) and Prematalac (Cow and Gate Ltd.) were examined--Prematalac is modified in an attempt to meet the specific requirements of the low birthweight infant. Nine premature infants were enrolled for two metabolic balance periods in a cross-over experimental design. At the onset the infants were randomly allocated one of two milks. Various anthropometric data were collected at the start and end of each 4 day balance. All infants received more energy and protein per kg body weight per day on Prematalac compared with Premium. Incremental weight, though satisfactory for both milks over the balance periods, was greater when Prematalac was fed compared with Premium (mean and (range) 46 (25-93), 19 (9-44) g per day respectively). No differences were detected for gain in length between the two milks. Mean percent digestibility of energy intake was similar for both milks (92%). Infants retained more nitrogen when fed Prematalac compared with Premium (mean (+SD) 477 (59) and 299 (30) mg per kg per day respectively). Neither milk was considered ideal, and we conclude that standard formulae are unable to support the potential for gain in lean body tissue of the premature infant.