The mammary pheromone of the rabbit: From where does it come?

Abstract

Newborn rabbits, Oryctolagus cuniculus, are directed to their mother's nipples by specialized odour cues. Previous investigations have suggested that these cues are released from the doe's abdominal surface from structures located around the nipple. We tested pups with samples of various cutaneous tissues or fluids collected from lactating females to determine the location of the source of the odour cues. After finding that the nipples from lactating does were more attractive than those of virgin females, we conducted three experiments using skin samples collected at increasing distance from the nipples, dermal and mammary tissues taken below the nipples, and milk collected at different levels of the mammary pathway. These different substrates were assessed for their ability to elicit searching/grasping responses in pups. Efficient odour cues were released only from the nipples, whereas the dermal or mammary tissues sampled beneath the nipples were behaviourally inefficient, and milk became behaviourally active only after it had flown through the nipple. These results suggest dual exocrine sources of active factors from the nipple of lactating rabbits: cues released within the nipple that render milk behaviourally active and cues distributed over the nipple epidermis. © 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.