Heated bottle

Rosa • 🐶🐱👨‍👩‍👦‍👦

If I heat up a bottle of breast milk and my baby falls asleep before I can give it to him can I put that bottle back in the refrigerator or should I wake him and feed him?

If the bottle contains 5 ounces of milk and he leaves 2 ounces can I leave that bottle out? Certain amount of hours? Do I toss the leftover milk no matter what?