I have four cats and have been "free" feeding them for a long time. Today I took one in for a check up for blood in his stools and the vet put him on Iams Vet Formula Intestinal Low Residue. I usually feed them Blue Buffalo Spa Select Indoor but the vet said they never heard of it and said I need to change the food. So I guess I need some advice on how to change them to a meal plan (feeding them two times a day) I have to so I can feed the special food to my one cat and the other food to the other three, any advice?