Depends. There are many treats you can buy at the feed store, apple, carrot treats. Apples and carrots (no more than 1/day) are nice treats. I like oatmeal cookies, and their easy to buy at the super market. Many horses like peppermints. There are lots of others.
I spoil Christy, she gets 1 carrot, 1/2 apple, both choped up so she doesn't choke, and 1 oatmeal cookie every evening with dinner.
If I forget any of these, she really lets me know! As in Scream, then looking at me like "Mom, you forgot my yummy! How can I eat without my yummy?" Guilt trip!