Malnutrition during the reproductive cycle: effects on galactopoietic hormones and lactational performance in the rat

To examine the effects of malnutrition imposed at various stages of the reproductive cycle on galactopoietic hormones and lactational performance, rats were fed 50% of the intake of ad libitum-fed controls either before and during pregnancy (refed), during lactation only (acutely restricted), or throughout the experimental period (chronically restricted). Milk yield and litter weight at day 14 of lactation were compromised in the groups restricted during lactation. Dietary restriction during lactation had consistent negative effects on milk nutrient and energy contents. Plasma and milk corticosterone values were twice as high in the groups restricted during lactation as in the controls. Corticosterone but not prolactin values were correlated with many measures of lactational performance. These results suggest that the increase in corticosterone values may be one mechanism by which malnutrition exerts its effects on lactational performance.