This might be controversial to some on here, but I live in the city and have a hard time getting out to a feed supply store. I use dry cat food or premium puppy food. It's usually somewhere between 27-33% protein. I also use mashed up hard boiled egg yoke. For those that live in the city, a lot of body builders eat nothing but egg whites and throw out the yolks. Its worth the time to put a flyer up on the bulletin board at the gym looking for their discarded egg yolks. Just have them throw them into a ziplock bag and into their freezer and pick em up once a week from them. Free for you, and no guilt about throwing out good food for them.