Second-hand eating? Maternal perception of the food environment affects reproductive investment in mice

Little information exists on how perception of the food (or "energetic") environment affects body composition and reproductive investment. The hypothesis was tested that female mice, who are themselves consuming standard chow diets but who are exposed to conspecifics eating a rich "cafeteria diet," will exhibit altered weight gain and reproductive investment.

Female C57BL/6 mice were raised on a cafeteria diet. At maturity, subjects were switched to a standard chow diet, and their cage-mates were assigned to consume either a cafeteria diet (treatment, n = 20) or standard chow (control, n = 20). Subjects were mated and pups raised to weaning. Subjects and pups were analyzed for body composition.

Treatment had no discernable effect on dam body weight or composition but caused pups to have lower body weight (P = 0.036) and less fat mass (P = 0.041). A nearly significant treatment effect on "time to successful reproduction" (avg. 55 versus 44 days), likely due to increased failed first pregnancies, (14/19 versus 8/19, P = 0.099) was found.

These data indicate that perceived food environment (independent of the diet actually consumed) can produce small pups with less body fat and possibly induce difficulties in pregnancy for dams. Replication and mechanistic studies should follow.