New "d'uh" discovery today while making 30 pounds of cat food (living with a growing kitten, you know): don't toss those egg whites! Sure, don't use them raw in the food, but cook 'em up to kill the biotin-blocking avidin, grind 'em up, and mix them in with the raw cat food.
It's less wasteful and a brutally cool source of phosphorus-free protein! Dr. Pierson suggested this idea long ago but I finally implemented today. Easy.