The ontogeny of hyperphagic behavior in the Zucker fatty ( fa/ fa) rat was examined. Wild-type, +/ fa, and fa/ fapups aged postnatal day 5( P5), P9, P12, P15, and P18 were evaluated using a test that measured ingestive behavior independent of the dam. The independent ingestive test consisted of giving pups access to a test solution [half-and-half (cream and milk)] on a tissue on the floor of a ...