Investigation of the functions of coprophagy in juvenile rats.

A series of experiments were undertaken to examine possible functions of the ingestion of maternal anal excreta by juvenile rats. No strong support was found for hypotheses suggesting (a) that maternal excreta serves as a major transition diet from mother's milk to solid food, (b) that ingestion of maternal excreta influences pup diet selection at weaning, or (c) that ingestion of mater-nal excreta is a necessary condition for inoculation of pups with enteric bacte-ria. Some support was found for the hypothesis that maternal excreta can serve as a short-term emergency food supply for rat pups after weaning. It is proposed that pup ingestion of maternal anal excreta may not be a functional-ly meaningful unit of behavior in preweaning rats. Allocoprophagy may be one facet of a broader pattern of oral exploration in which functional signifi-cance resides. During the 17-day period when newborn rats are totally dependent on their dam's milk for sustenance (Babicky, Parizek, Os-tadalova, & Kolar, 1973), they mouth and possibly ingest samples of most of the solid objects with which they come in contact. Under standard laboratory maintenance conditions the anal excreta of the dam are one of the substances samples of which are frequently contacted, chewed, and appar-ently swallowed by juvenile rats. Although there are reports in the literature of mouth-ing and chewing of maternal excreta by the young of numerous mammalian species (Ewer, 1968, p. 274), including the rat (see, e.g., Bolles & Woods, 1964). Leon (1974) was, to my knowledge, both the first to re-port stomach content analyses indicating that rat pups actually ingest maternal ex-creta and the first to consider systematically