Changes in appetitive behavior in weanling-age rats: transitions from suckling to feeding behavior

To help identify determinants of rat appetitive behavior during the weanling period, rat pups 17-32 days of age were studied in a Y-maze. One arm of the maze provided pups with the opportunity to suckle a lactating or nonlactating anesthetized female. The other arm always contained a familiar food, either liquid diet or ground laboratory chow. In some experiments the dam was separated from the food compartment by a thin gauze screen. In other tests maternal contact could be maintained in the feeding goal but suckling in that compartment was prevented by nipple involution. Age was the major determinant of choice, with more older animals choosing the food arm. Availability of maternal contact in the feeding compartment increased the percentage of rats that chose to feed by about 20% at all ages studied. Food quality, but not quantity, affected choice at each age, as did lactational status. Prior food, water, and maternal deprivation (2 or 24 hr) did not affect choice behavior at any age but did influence behavior in the goal box. These findings are discussed within the context of the changing demands faced by the rats during the weaning period.