The appetitive behavior of 3to 6-day-old rat pups was studied by testing their ability to direct their ingestive behavior to a restricted food source. We found that, from 3 days of age, pups were able to feed efficiently from such a source. More specifically, pups that were deprived of nutrition but not of maternal care as well as pups that were dehydrated ingested significantly more than nondeprived animals, and did so whether liquid diet was spread over the entire floor surface beneath them or restricted to a fraction of the floor surface. However, pups that had been nutritionally and maternally deprived were not able to direct their feeding. The general locomotor activation of pups in this latter group appeared to interfere with their ability to direct their behavior to the restricted source. These results indicate that from early ages, developing rats possess the appetitive competence to guide their behavior and suggest that previous findings of poorly directed behavior were a confound of the behavioral activation shown by pups tested in a state of maternal deprivation.
Ingestive behavior, like other appetitive behaviors, is composed of a sequence of response elements or components. For altricial rodents, this sequential organization is particularly obvious during early postnatal development, a time when a number of these ingestive components can be conveniently isolated for study. Recent developmental studies of independent ingestion in rats have focused on the final, consummatory components in the sequence and have yielded information on the sequential emergence of intake controls (see reviews, Hall, 1990, 1991).