The tammar wallaby: a model to study putative autocrine-induced changes in milk composition

The marsupial newborn is immature and the mother has the capacity to alter milk composition significantly during lactation, presumably to meet the nutritional requirements of the developing young. Furthermore, macropodid marsupials may practice asynchronous concurrent lactation (ACL)7 whereby the mother provides milk which differs in all the major components from adjacent mammary glands for two young of different ages. This phenomenon suggests that local regulation of mammary function, in addition to endocrine stimuli, is likely to be important for controlling milk composition. This paper explores the possibility that changes in sucking patterns of the young represent the first step in a mechanism to signal the mammary gland for putative autocrine-induced changes in milk composition.