Maternal pheromone in Rattus norvegicus.

A replication was undertaken of the finding that rat pups between 14 and 28 days of age will approach an attractant (maternal pheromone) contained in the excrement of lactating female rats. Preweaning pups from three strains of Rattus norvegicus (hooded PVG/C, Wistar, and Sprague-Dawley) were tested under different apparatus conditions, with different stimuli, and with different pretest experience. Despite attempts to maximize the attractant olfactory properties of stimulus material no clear evidence of maternal pheromone could be demonstrated. The use of olfactory cues, and an ability of rat pups to discriminate maternal odor, were shown. But such behavior falls short of that which would merit the use of the term pheromone.