You can also open your "Combat" chat tab while feeding your pet to see how "happy" it is getting.
I use
Simple Buff Bars (it's not Cataclysm ready, but it still does the job for me) and it will allow you to show pet buffs and debuffs.
By-the-way, UF stands for
Unit
Frames (in this case, anyway). They show your health, power (manna and what not) and the default ones use a portrait of your character.