Animal Tankage has been documented to contain 9%N and 6%P, as for micronutrients and other items of value I am not sure. But I do know that if you manufacture the bone and blood (steamed bonemeal, and dried blood meal) the items are much more profitable to organic fertilizer manufacturers. I know of at least one in the Mid-Atlantic region that would likely take all the blood/bone meal you could give them. How much are you dealing with? Also check out this link below, it gives NPK composition for various natural fertilizers: