About digestibility of meat...
My dog is a 50-lb English Bulldog.
He gets about 1.5lbs of prey a day and eats once a day - random times because I don't follow a routine feeding schedule (on purpose). He poops once a day, sometimes once every 2 days. And this is the size of his poop:
That poop tells me he ate beef hearts for his last meal. The pork and fish and rabbit and chicken are lighter color. If he's getting too much bone it turns white so I let off the bone. If it turns black he had too much organs. The poop dries up and crumbles if you leave it (I tested it so I let it stay for 3 days before I couldn't stand it anymore). It's perfect for if you use one of those doggy dooley things. I use a home-made version of it. It doesn't stink as much as kibble poop either.
Yeah yeah... I derailed the thread from food to poop. LOL.