One of my first serious jobs was working in a butcher store, which I did fulltime for a year, and then parttime for another, when I started my studies. I started sweeping the floor and throwing the crap in the garbage but in the end I was serving customers and piecing sides of beef into roasts and whatnot. What it left on me, apart from an intimate knowledge of how to cut a quadrupede, was that when you kill an animal, you better eat everything you can, and use the rest for something worthy, because there's a whole lot more to a beef than the good cuts. I can't count the number of fancy clients I served who would buy nothing but filet mignon, and in the end it really bothered me that when you tried offering them a different cut that was less known (we were doing French cut, so there's a finer division of meat than in American) but just as tasty, they would give us the weird look. We were constantly left with extras from the less fancy parts (neck, shanks, etc) but never from the prime cuts. For my part, I've learned to cook tail, feet, and neck properly, and they are as much favorites as finer cuts.
It still bothers me that so much waste must happen so that Joe fancy gets his fillet. Animals are discrete resources, not continuous ones. You can't produce only sirloin without byproducts, at least until we bio-engineer our steaks--when that happens I'd rather be a full vegan. For now I'd rather see bones and marrow go into gelatin than into more waste in the dump. It's a minimal act of respect towards the animal one's been eating.