Pre- and postweaning food restrictions interact to determine reproductive success and milk volume in rats.

This study was designed to determine if nutrient availability during gestation and early life modifies the effects of subsequent dietary intake on reproductive and lactation performance. Rat pups, whose mothers had been allowed free access to food or were food-restricted to 50% of ad libitum consumption were assigned to free access or food restricted groups after weaning, creating 4 groups (pre- and postweaning diet). Pre- and postweaning diets interacted significantly to influence age at conception, number of pups born, and milk yield on d 14 of lactation. Early undernutrition deterred conception in dams later allowed free access to food and resulted in fewer pups born to dams later allowed free access to food, but not those in the food-restricted group. By d 15 of lactation, only dietary treatment after weaning influenced litter weight. Milk yield per gram dam weight was not impaired in the food restricted-ad libitum group but was lowered in dams in the ad libitum-food restricted group. Milk yield per gram litter weight was not impaired in ad libitum-food restricted dams but was reduced in food restricted-ad libitum dams. These results extend to the preweaning period our previous finding that past or current food restriction impairs reproductive success and decreases milk yield in rats.