Nutritional variables and their effect on the development of ultrasonic vocalizations in rat pups

Measures of ultrasonic vocalizations were made on alternate days during the first and second weeks postpartum in rat pups reared by mothers fed either control (23%) or low protein (8%) diets. Compared to those reared by control mothers, pups reared by low protein mothers emitted significantly fewer ultrasonic vocalizations. The hypothesis that malnutrition might shift the age at which peak rate of vocalizations were emitted was not confirmed.