You never mentioned renal issues and our discussion was about
ineterstitial cystitis. I was going from the standpoint of keeping a
consistent urine ph, and also the fact that store brands generally don't
have a fixed formula which means the ingredients, quality of such, etc.
are never consistent.
As far as phosphorus levels go, the two brands are not that far apart
and if your cat is in the early stages of renal failure you don't want
to reduce protein at this point. A better food than either of these in
terms of low phosphorus is Innova Light canned food.

Megan

                                   

Protein shouldn't be restricted until the BUN reaches >60 mg/dl - and then
*only* to control azotemia.  Prematurely restricting protein in CRF cats can
result in a reduced resistance to infection, reduced hemoglobin production
and anemia, and muscle wasting because the cat will begin to metabolize
*body* proteins to meet their protein needs.  Also, CRF cats are constantly
losing protein in their urine, so, you don't want to restrict protein unless
you absolutely must to control azotemia.

The *best* non-prescription diets for CRF or renal insufficiently are
PetGuard and Wysong (if your cats will eat them).  Both have good protein
levels and excellent phosphorus levels (~0.20% DMB).