Undernutrition by rearing in large litters delays the development of reflexive, locomotor, and memory processes in mice.

In 3 experiments with a total of 512 Swiss-Webster mice, the effects of early postnatal undernutrition on the ontogeny of several behavioral capacities of varying complexity were investigated. After birth, mouse pups in all experiments were reared in either normally nourished or undernourished conditions by maintaining litter sizes at 6 or 16, respectively. Exps I and II examined the development of adultlike patterns of swimming behaviors and spontaneous locomotor activity, respectively, as a function of litter size. The maturation of both behavior patterns was delayed by about 2 days in the 16-litter mice. In Exp III, normally-nourished and undernourished Ss received 25 trials in a shock–escape T-maze at 9, 11, and 13 days of age, followed by similar retention tests 24 hrs later. Although litter size had little effect on correct turns at each age during training, Ss reared in litters of 6 showed significant retention of prior training by 12 days of age, whereas comparable retention was not noted for the large litter mice until 14 days of age. Results suggest that nutritional deficits, imposed by rearing in large litters during the postnatal period of rapid CNS maturation, retard the development of behavioral capacities involving both unlearned and learned responses. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)