Bird food is real fatty. Mice enjoy it, but it makes them obese. A dogfood fed or carrot fed mouse will probably be less healthy than a birdseed fed mouse, since one, too much protein is bad for mice, and two, too much carrots give mice the runs.
I feed my breeding colony 25% kitten chow (them females need their protein if they're constantly giving birth to 12 a litter), 50% seed and grain, like sunflower seeds, millet spray, wild rice, oats, barley, grass seeds, corn, etc, and 25% miscellaneous, small pieces of fruit, veggies, yogurt drops, cereal, milk, bread, mealworms, peanut butter, table scraps. I also give them full spectrum lighting since it gives em Vit D (which gives my snakes nice healthy bones and gosh those teeth). Tons of excersize too, 2 wheels, a couple ropes for climbing, logs, tubes, random stuff. I also play with them alot, the non-pregnant ones. And you wonder why they all have 12 pups per litter...
-Lemur 6