The chap who told me this (relative) has since died, as I didnt ask him why to cook it, just took his word because he was fantastic with dogs, I can't answer that sorry

he always swore by natural feeding, they did the meatman run every month, cutting up the tripe etc (uck lol) and feeding with a good quality mixer. All I know is that he said when he had a dog that had lost weight, feeding lamb breast that had been cooked but with the skin not crispy was a good way to improve coat and to put some weight on. I saw him take poor, malnurished dogs and improve them in a short period of time, the tlc from him and his wife did a lot too I think, and they also reared a couple of puppies the natural way, and he insisted that the addition of lamb cooked this way helped them to grow as wonderful as they did. He hated my choice of bagged dry food :) But when I had a dog that had been seriously ill, I followed what he suggested, and despite her having lost so much weight, she really did improve by following what he said. So, I just put my post as a suggestion, and I really wish i'd asked him why :D