What ingredients go into the food you mix? If you don't mind sharing your secret, I've been hoping one day to enter one of my rats into a rat show, and they always look too wild to have a chance though!
I live near a co-op with really great organic grains in bulk bins. I mix 7 grain rolled oats as the base, then add a little rice (white and brown), buckwheat, millet, sunflower seeds (raw unsalted), pumpkin seeds (raw unsalted), almonds (raw or cooked, unsalted), barley, rye,flax seed ... I just try to get a little verity in the grains but it varies depending on what they have available. I also mix in strips of nori and I give them Natural Balance vegetarian dog food [link] in small amounts. They get fresh fruits and veggies every day. no oranges, no onions, limit salt to a minimum. They also get scraps from my meals which are pretty healthy.