New Zealand is the largest meat-exporting country in the world. It ships about 500,000 tons of meat to more than 30 countries, most of it to Britain (sheep and lamb) and to the United States (beef). Meat by-products are important, since only half the weight of an animal is dressed and sold as meat; the estimated proportionate values of the dead animal efficiently used are: meat, 80 per cent; hide, 12 per-cent; by-products, 7 per cent. By-products account for almost 20 per cent of a total meat-export value of £100 million a year. The hide or skin, hair or wool, hoofs, bones, intestines, glands, and fat produce the following by-products: hides, skins, and pelts; wool and hair; runners and casings; tallow; meatmeal, dried blood, meat and bone meal, etc.; and miscellaneous (including rennet, glue, gelatine, surgical gut, neatsfoot oil, glands for extracts, etc.).
The fellmongery department handles skins and hides to produce pelts, pickled hides, wool, and hair. Exports in 1960 included 25,988,000 sheep and lamb pelts; 1,236,000 woolly skins; 807,000 cattle hides; and 1,029,000 calf skins. Sheep skins are treated with depilatory paint to loosen the wool which is rubbed off by hand, so leaving the pelt. The wool is washed, sorted, and sold; the pelt is sold for making fine leather for gloves, bags, and the like. (A New Zealand freezing works may handle 10,000 sheep and lambs daily at peak season.) Cattle hides are cleaned, salted, pickled for a month, and sent to local or overseas tanneries.
The gut house or gut department deals with all viscera, except edible livers. After its removal from carcasses on the floors above, the viscera is sent down chutes to the gut house in which the intestines (runners), fat, etc., are separated. Casings: Sheep and lamb runners are processed by special machinery to avoid damage. The mucous membrane and the outer layers must be removed from the intestines to form the finished (sausage, etc.) casings. An average lamb casing is about 80 ft long–the 18 million lambs slaughtered each season produce roughly 300,000 miles of casing. In 1960, 9,410,000 lb of casings were exported to the United States for sausage skins.
The rendering department renders the fat and unwanted animal tissue into tallow and residual meal, either by “wet rendering” in a digester (something like a domestic pressure cooker), or in a “dry melter”, in which an outer jacket, heated by steam, cooks the contents of an inner vessel in their own moisture at a pressure of 40 lb a square inch.
Tallow: Edible tallow (dripping, etc.) comes from selected clean fats. Much of this can be now rendered down at low temperatures by prior grinding of the fatty tissues to release most of the fat. In 1960, 72,214 tons of tallow were produced, including 49,661 inedible, 21,537 edible; lard, 230 inedible, 786 edible. This is almost double the pre-war production.
Meat meal, meat and bone meal, bone meal, blood and bone fertilisers: These are obtained from the dried and ground residue left after the tallow has been extracted. The difference in the end product depends largely on the difference in the ratio of protein to bone in the original material. Blood meal (dried blood) and liver meal are also produced, the latter often including ground, dried lungs also. In 1959, 47,500 tons of meal were produced, including 33,114 tons of blood and bone, 3,941 of bone dust, 3,229 of blood meal, and 5,416 of others. Export of meat meal is controlled to provide enough for local poultry feeding. 9,600 tons of liver meal were exported. (Meat extract can also be classed as a by-product of the canning department. In 1960, 339,000 lb of extract were produced.)
Miscellaneous by-products: The glands and other organs saved for pharmaceutical purposes, though less in bulk, are important as a source of hormones; their importance to human welfare far outweighs the monetary returns from them.
Calf vells or stomachs (from bobby calves) are dried and used for the manufacture of rennet. In 1959, 373 cwt of dried vells, worth £96,677, were exported.
Pituitary bodies from the base of the brain are sometimes collected and saved for the manufacture of pituitrin, pitocin, and ACTH. These are very small and hard to handle, as they must be frozen quickly. The pancreas gland, near the stomach, is often saved as the source of an important proteolytic ferment called trypsin. Insulin is made from a special part of the gland. Parathyroids, spleens and adrenal bodies, gall or bile are saved for either pharmaceutical or industrial use.
by Ian Greville Watt, M.SC., B.V.SC., Director, Meat Division, Department of Agriculture, Wellington.
(Latest figures for this article are not readily available, March 1965)