Cats should never drink cows milk, goats milk or milk that comes from any other animal that is sold for human consumption.
Cats can however drink specially made milk for cats. These cat milk products are lactose-free, because cats are lactose intolerant.
Cat milk brands are intended as a supplement as well as to give to kittens. Very young orphansed kittens however should be given a more specialized cat milk replacement product whcih contains a host of other nutrients inlcuding required vitamins, protein and taurine that a very young kitten needs when they can not nurse from the mother.
The milk in cat milk products are not sourced from cats – it is usually modified cows milk with the lactose removed