THE BOG INIM'STKY. 129 
culture in thai seel ion yet to be solved satisfactorily. [t is not diffi- 
cult to appreciate whal maybe gained if some of this by-product, 
which has such high feeding and fertilizing value, and which is 
exported in such enormous quantities, can be converted into pork 
products, which are now largely imported from other Stales. 
PACKING-HOUSE PRODUCTS. 
The frugality of the modern meat packer has become almost pro- 
verbial. Less than twenty years ago the disposal of the offal of slaugh- 
tering was a problem, but at present there is very little waste, and the 
packer has actually come to regard the by-products as the principal 
source of profit in his business. The preparation of these by-products 
for use as animal feed is one of the later developments of this branch 
of the industry. Fertilizers have long been prominent in the sales, 
the material that enters into their composition being meat scraps, 
blood, bone, hair, intestinal contents, etc. The use of tankage, a by- 
product that has had its sale entirely as a fertilizer, is growing among 
pig feeders, and has been studied by Plumb and Yan Norman at the 
Indiana Station, and by Kennedy and Marshall at the Iowa Station. 
Beef meal is also a packing-house product, whose feeding value was 
studied along with that of tankage in the Iowa experiment. 
Character of packing-house by-products. — Plumb and Yan Xorman a 
state that tankage may contain scraps of meat, intestines, and their 
contents, hair, etc. It is classed as concentrated and crushed tankage. 
Concentrated tankage is not used for animal food. Crushed tankage 
is said to be of several grades, being graded according to the ammonia 
and phosphoric-acid content, although it is probable that the tankage 
graded as No. 1 is free from the contents of intestines- 
Kennedy and Marshall 6 used two brands of tankage made by Chicago 
packers. One of these is described as follows : 
Digester tankage is made from, meat scraps, fat trimmings, and scrap bones. 
These are taken up as fast as taken from the animals and put into a large steel 
tank and cooked under a live steam pressure of 40 pounds to the square inch, 
which cooks out the tallow. After the steam is turned off it is allowed to settle, 
when the grease rises to the top and is drawn off. After the grease is drawn off 
the tankage is kept agitated, and by evaporation the water is extracted until the 
tankage contains about 8 per cent moisture. It is then taken out of the tank, 
allowed to cool, is ground, and stored ready for shipment. This tankage is sup- 
posed to contain about 60 per cent protein and 10 per cent fat. 
The manufacture of the other tankage is thus described : 
This product, like the one just described, is made from meat scraps, scrap bones, 
eta Quoting the words of the manufacturer, it is as follows: u Tankage is the 
product which drops to the bottom in our rendering tanks when we are rendering 
out grease, tallow, etc., at our various packing houses. It has been thoroughly 
cooked iinder 40 pounds pressure for several hours, which thoroughly destroys 
any disease germs which might possibly be in the raw meat. This product is 
«Bul. No. 90, Indiana Expt. Sta. & Bui. No. 65, Iowa Expt. Sta. 
8396— No. 47—04 9 
