http://www.epa.qld.gov.au/nature_conservation/wildlife/caring_for_wildlife/carers_kit/mammals/marsupials/#gen4 "Milk for marsupials Eutherian milk (e.g. cows’ milk) and milk produced by marsupials are very different. Eutherian milk has a fairly stable composition, whereas the composition of marsupial milk can change dramatically with the different stages of the young’s growth. Some species of kangaroos can produce two types of milk for suckling joeys that are at different stages of growth. Companies such as Wombaroo and Biolac have developed formulas for the various stages of joey development. Contrary to popular belief, marsupials are not lactose intolerant. Their milk contains about 2 percent lactose, which is less than cows’ milk. Joeys can suffer from a lactose-induced osmotic diarrhoea if given cows’ milk in large volumes." A lot of other website seem to state that they are Lactose intolerant/allergic to Cows milk, but only base this on the assumption that because Roo milk has less lactose than cows milk, and Cows milk gives Joeys diarrhoea: they must be Lactose intolerant/allergic. This isn't technically true. Either way, its better to give the animal a suitable and tailored formula that contains what the particular species needs in its diet. Hope this helps!