: I agree cutle bone is a very good source of calcium for turtles. As for milk....I think who ever told you that was either really misinformed himself/herself, or he was just messing with you.
Milk? I don't really see how you would accomplish that. Why don't you just feed your turtle cuttlebone. Chip of the shell, break it into pieces, and float it in the tank. This will provide them with plenty of calcium if you add it a couple of times a week.