Dog Food (Purina)

Question

Just to be on the safe side, let me give you the other non-chemical ingredients, to see if there is any Hametz. mixed tocopherols, animal digest, potassium chloride, garlic oil. The rest are chemicals. I am very happy that appears not to be hametz, but I am curious, what are oat groats and brewers dried yeast? From the sound of it, I thought that this would be hametz. Thanks.