Creatu lose 10 points of hunger each day. Some of us rely solely on the apple tree to feed our pets because we don't have the tu to buy foods. So when it starts granting foods that only fill 1 point hunger, pets just get hungrier and hungrier.
Some apples are at 25 or so hunger points if I'm remembering correctly. So my suggestion is simply this:
Make apples a flat 10 points. Take the extra points off the higher ranked apples and slap 'em on the garbage ones.