MILK-COMPOSITION IN THE NORTH-AMERICAN OPOSSUM (DIDELPHIS-VIRGINIANA)

The composition of milk samples collected from captive opossums (Didel phis virginiana) was determined at various intervals during lactation. The milk solids increased from 9% at week one to a maximum of 34% at 11 weeks post partum. There were changes in the relative proportions o f protein, lipid and carbohydrate at different stages of lactation. Li pid represented the greatest fraction of the solids except for a perio d at mid-lactation when there was a peak in protein concentration. The concentrations of sodium, potassium and magnesium were relatively con stant, 41 +/- 4, 35 +/- 11 and 9.2 +/- 1.6 mmol respectively, although calcium increased from 13 +/- 5 mmol at week one to a peak of 112 +/- 35 mmol at 9 weeks.