MILK CONSUMPTION AND GROWTH IN A MARSUPIAL ARBOREAL FOLIVORE, THE COMMON-RINGTAIL-POSSUM, PSEUDOCHEIRUS-PEREGRINUS

This study examines the milk consumption and growth energetics of the smallest arboreal folivore in Australia, Pseudocheirus peregrinus. Mas s increase was sigmoidal, and young ceased sucking milk between 27 and 30 wk (mean = 29.3 +/- 1 wk). This length of lactation was 129% of th at predicted allometrically from data for other marsupials. The mean G ompertz constant (0.01) calculated for seven young suggests that P. pe regrinus has a slow rate of growth compared with other marsupial speci es. Milk intake was measured with isotopic turnover techniques. The es timated total milk energy yield (11.9 MJ kg(-1)) for a ringtail possum suckling two young was similar to that of the only other marsupial he rbivore for which data are available (Macropus eugenii). However, peak milk energy output (154.4 kJ kg(-0.75)d(-1)) was lower than that in o ther herbivores. The body mass accrued from milk consumption by young ringtail possums at various stages of lactation was similar to that of other marsupials, suggesting that the slow rate of growth in this spe cies is a result of a limited rate of supply of milk energy from the m other and not an inefficient conversion of milk energy in the young.