Changes in Milk Carbohydrates during Lactation in a Didelphid Marsupial, Monodelphis domestica

Abstract

Monodelphis domestica, the gray short-tailed opossum, is a small South American marsupial. The aim of this study was to examine qualitative and quantitative changes in the carbohydrates in the milk of this marsupial during lactation and to determine whether these are similar to those found in the milk of Australian marsupials. Twenty-one milk samples collected between days 1 and 75 of lactation were analyzed. The carbohydrate (hexose) concentration was 3% (w/v) on day 1 postpartum, gradually increased to 13% by day 50, and decreased to less than 1.5% by the end of lactation. Galactose was the major monosaccharide constituent of acid hydrolysates of the milk carbohydrates, with hexosamines, glucose, and sialic acid being only minor constituents. Thin-layer chromatography showed that the carbo-hydrates consisted of a variety of oligosaccharides, some of which could be identical with oligosaccharides of known structure previously isolated from milk of the tammar wallaby, Macropus eugenii. In general, the changes observed in the milk carbohydrates of M. domestica were similar, but not identical, to those reported for other species of marsupials.