I just purchased auto feed today thinking it would save me the time and hassle of clicking individually through all of my soon to expire food items. Unfortunately, that is not so. The feed all button currently requires you to select a type of carcass you want to use. If you have lots of low use carcasses, this still requires a bit of clicking.

My suggestion is to add an option at the top that is 'Any Carcass' that will use anything you have in your inventory. In addition, it would use them in order of expiry date so that all items expiring tomorrow always get used first.