The Living Force
I don't know about the nose to tail approach, but I think organ meats are in fact necessary. That is, there is something that you get from them that you can't get from muscle meats alone. Definitely for Vitamins A and D in the case of liver. I eat a pound of liverwurst a week, which is something like 3 or 4 meals.Anecdotally, I've always been a fan of liver anyway, and my local butcher is very obliging and supplied me with Ox heart and kidneys, so I've been enjoying including these organs in my diet for the variety and sheer deliciousness.. but are they necessary?