Gastrointestinal iron and cobalt absorption and iron status in young rats and guinea pigs.

The gastrointestinal absorption of Fe and Co by rats and guinea pigs of different ages was measured by comparing the whole-body retention of 59Fe and 57Co after oral and intraperitoneal administrations. The age-groups studied included newborn, weanlings and adults. The absorption of both Fe and Co decreased markedly with age in both rats and guinea pigs. In the rat, absorption remained elevated during the suckling period, while in the guinea pig absorption decreased markedly during suckling. In both species, Fe and Co absorption were similar, and remained elevated above adult values for some time after weaning. The generally greater absorption of Fe and Co by rats than by guinea pigs and the longer duration of maximal absorption in the rats may have involved differences in Fe status in the two species and differences in the timing of gut maturation.