The best-known illustration of the complexity of lactation in marsupials is the red kangaroo, Macropus rufus, in which two of the four glands may be lactating, each producing milk of different compositions, a third may be regressing after a period of lactation and a fourth gland may be completely regressed and quiescent (Griffiths et al. 1972). It is this diversity within the same animal which has intrigued many workers and the question most often asked is how can glands experiencing the same hormonal environment produce such radically different milks for young which have such different energetic requirements? Other aspects of lactation in marsupials also differ markedly from the eutherian pattern. Not only does lactation last longer than gestation but there are many changes in the mammary gland and the composition of the milk it produces during lactation which reflect the changing needs of the growing pouch young.
KeywordsMammary Gland Corpus Luteum Plasma Prolactin Milk Composition Early Lactation
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