Tolerance of pouch young kangaroos (Macropodidae) for cows' milk and milk replacers containing different amounts of glucose or lactose.

Abstract

Young Red (Macropus rufus) and Eastern Grey (M. giganteus) Kangaroos, aged between 150-190 days and between 200-250 days of age respectively at the start of the experiments, were obtained after their mothers had been shot by commercial shooters. A system of housing was developed so that they could be fed continuously by stomach tube and balance experiments performed. Experiment 1: Three joeys were each given six diets which contained (expressed as a proportion of total energy) either 6.6%, 13.3% or 20.0% of glucose or lactose. Measurements of dry matter excretion in faeces plus urine showed a decrease in dry matter utilisation at the two highest levels of lactose. Diarrhoea occurred in all joeys given the highest levels of lactose. No diarrhoea occurred in the joeys given equivalent amounts of glucose. Volatile fatty acid excretion was positively correlated with lactose intake. Experiment 2: Four joeys were given reconstituted dried whole cows' milk to provide a lactose intake similar to that given in experiment I at the intermediate level. Since cows' milk contains approximately 26% energy as lactose, the intake of milk had to be restricted severely. One joey developed diarrhoea. Experiment 3: Four joeys were given a carbohydrate-free milk replacer to provide control data for experiments I and 2. The chance occurrence of spontaneous bone fractures in two joeys after 5 weeks on the experiment necessitated an investigation of mineral utilisation. It was concluded that mineral requirements are very high in later pouch life and that tolerance for cows' milk and for lactose is limited to an intake of < 6.5 g lactose kg-1 d-1, or < 11-12 g d-1 for kangaroo joeys between 1.4-3.0 kg live weight.