1. The effect of maternal iron deficiency on milk composition and consumption by sucking rats was investigated.
2. Dams (n 42) were fed on semi-purified diets with either 8 (Fe-) or 250 (Fe+) mg Fe as ferrous sulphate/kg throughout gestation and lactation. Total milk intake was determined at days 7, 12 and 17 of lactation from the rate of disappearance of 3H2O from the total body water pool of pups. Measurements of milk constituents and Fe status of animals also were made.
3. Feeding the Fe- diet led to the development of anaemia in dams and pups and to growth retardation of sucking pups.
4. Concentrations of total lipid and Fe in milk from Fe- dams were significantly lower than those from Fe + dams. Mean milk intakes (ml/d) of Fe-deficient pups were 21 and 28% less than intakes of Fe-sufficient pups on days 12 and 17 respectively. However, when expressed per kg body-weight, mean milk intakes were similar between groups on days 17 and 12 and increased by 47% in the Fe-deficient group on day 17 of lactation.
5. It is concluded that maternal Fe deficiency affects the quality of milk ingested by neonatal rats. However, Fe-deficient pups are at least partially able to compensate for reduced milk energy and nutrient contents by increasing intake in late lactation.