412 Western Lwve-stock Management 
be used for longer than six weeks. It can usually be 
obtained at a price little above that of linseed-oil 
meal. 
Tankage, one of our best supplements, is a by-product 
of the meat industry. Scraps of meat and other offal 
from the slaughter houses are cooked in a closed steam 
tank to remove all the grease. After the grease is skimmed 
off the residue is dried and ground and the better grades 
used for pig feed and the poorer grades for fertilizer. 
Tankage is commonly the cheapest source of supplemental 
protein, and is likely to remain so, since it is not used by 
any other stock and must, therefore, be sold to the hog- 
raiser. Tankage is the highest in protein content of all 
the feeds named,. carrying twice as much as linseed and 
soybean meal, and a fourth more than cotton-seed meal. 
It may be fed for an indefinite period without injurious 
results. It carries nearly seven times as much protein as 
barley or corn, and costs but twice as much. 
In localities adjacent to creameries and cheese factories, 
skim-milk, buttermilk, and whey are often available in 
larger quantities than are needed for younger pigs, and 
these by-products of the dairy industry all have value 
for fattening pigs. Used in quantities of two to ten pounds 
a head, the Oregon Experiment Station has found skim- 
milk to have a value of about 22 cents a 100 pounds as 
compared with tankage at $45.00 a ton. As compared 
with barley feeding alone, it doubtless has a much 
higher value than this. Some experiment stations give 
it a value double this, when compared with corn feed- 
ing alone, but it is obviously more fair to compare it 
with the cheapest satisfactory source from which sup- 
plemental protein can be secured, since grain alone is 
always unsatisfactory. 
