Breeding cows can consume more than one wheat

Feed a cow wheat, and he shows the hearts. You can keep feeding him wheat and he consumes them. However, after he breeds with another cow, he will not accept wheat.

It seems like once he shows the hearts, he shouldn't accept any more wheat. That would make it easier to mass-breed a large field without wasting wheat.

This may affect other animals too. I have not tested recently except on my cattle farm.