You feed the snake what it will eat. If it wants to go back to mice, then feed it mice. If it wants rat weanlings, then feed it that. If you're worried about saving a half a dollar per meal, you're probably in the wrong hobby/side business. I learned LONG ago, that if a snake wants a cheesburger, you feed him a cheesburger, if he wants prime rib, feed him prime rib. Don't try and figure out why a snake does what it does.

I'm not trying to be mean here, but your snake will have a favorite food of the month. Just be glad you can find out what that is and keep them feeding.

Good luck!
Jim Smith