Purina, along with all the other pet food found in the grocery store, is garbage - literally. It is made with the waste from the human food industry, the not-fit-for-human consumption grains and slaughterhouse waste.
Every pet owner should read this article from the Animal Protection Institute:
What’s Really in Pet Food
If you can't find any good quality food locally, you might want to try Pet Food Direct. Their prices are lower than pet stores and they run sales constantly which will offset the shipping costs.
http://www.petfooddirect.com/store/d...-Header-_-Logo