Publisher Summary This chapter discusses that lean, which is removed from the bones by machines, is termed “mechanically deboned meat.” The potential yield of mechanically deboned meat can best be estimated by first understanding what proportion of the carcass is bone and what proportion of the bone is lean and marrow, which mechanical deboners can recover. When mechanically deboned meat, fish, and poultry began to be commercially produced, regulatory agencies in most countries looked at the product in the same way they did at hand-boned meat. Objections to mechanically deboned meat by some farmers and ranchers and some in the labor force have been largely economic in nature. Calcium is the chemical means by which bone content of mechanically deboned meat is determined; calcium content is closely associated with ash content. The term “heavy metal” is often used to describe toxic elements. In the chemical sense the term refers to the detection of metal impurities by precipitation reactions. Kolbye and Nelson (1977), in their study of the health and safety aspects of mechanically deboned meat, did not include nucleic acid or purine content. From a theoretical standpoint a positive or a negative view can be taken regarding the microbiology of mechanically deboned meat. The chapter discusses that the vitamin content of mechanically deboned meat may differ from that of hand-boned meat because of the presence of the red marrow.