COMPOSITION OF MILK OF THE COMMON BRUSHTAIL POSSUM, TRICHOSURUS-VULPECULA (MARSUPIALIA, PHALANGERIDAE) - CONCENTRATIONS OF ELEMENTS

The concentrations of 11 elements (calcium, copper, iron, magnesium, m anganese, phosphorus, potassium, sodium, strontium, sulphur and zinc) were measured in milk samples collected from 193 lactating brushtail p ossums, Trichosurus vulpecula, at all stages of lactation. Most elemen ts showed patterns of change during lactation similar to those of othe r marsupials. The most marked changes occurred at about 80-120 days, w hen the growth rate of the pouch young increased and developmental cha nges took place, such as eye opening and fur growth. Compared with eut herians, copper and iron concentrations were high in possum milk, as i n other marsupials, but zinc levels were exceptionally high. Strontium and manganese levels, not measured before in marsupial milk, were con siderably higher than levels reported in eutherian milk. In contrast t o eutherian mammals, marsupial young must be supplied with large quant ities of minerals in the milk as almost all growth and development occ urs after birth, and possum young are entirely dependent on milk suppl ied by the mother for about the first 100 days.