Tuberculosis in Line Stock. 
11 
way. It has been observed frequently that cattle which stand on 
either side of or face tuberculous animals in barns are the first to 
contract the disease. 
The continuous water trough in barns is also accountable to a 
very large extent for spreading the disease. Cattle may become 
infected by picking over manure infected with the germs of tubercu¬ 
losis. Hay, straw, or any other feed contaminated with the germs 
may give the disease to animals that consume such material. 
Water holes and creeks into which infected milk or the washings 
from infected milk cans have been dumped may also be a source 
of the infection. The teat siphon or milking tube, in a number of 
instances, has been the medium by which the disease has been con¬ 
veyed from one animal to another. Calves contract tuberculosis 
by nursing, even for a short time, cows whose udders are affected. 
Calves also become infected frequently by drinking milk from diseased 
cattle isolated from the main herd. To be safe for feed, milk from 
such cows should first be heated to a temperature of 145° F. and 
held there for at least 30 minutes, but as this method requires con¬ 
siderable attention to assure proper heating, boiling for a few minutes 
is considered a better plan. 
HOW SWINE MAY BECOME INFECTED. 
The tuberculous cow is not only a menace to other cattle hut is 
also the commonest source of infection to swine. In some parts 
of the country, especially where there are whole-milk creameries 
and skimming stations, feeding mixed skim milk to swine is a common 
practice. In that way the skim milk from one farm may be fed to 
hogs on another. Thus it is possible that milk from a few tubercu¬ 
lous cows may set up the infection among swine on many farms. 
Milk is a good medium for the development of the tubercle bacilli, 
and swine seem to be extremely susceptible to tuberculosis. Nu¬ 
merous instances are on record, also, in which the whole milk is 
separated on the farm, the cream shipped, and the skim milk fed 
to swine. Consequently one tuberculous animal that is passing 
the germs in the milk secretions may give the disease to any or all 
of the animals to which any of the milk is fed. Investigations made 
by the Bureau of Animal Industry show that in practically every 
instance where tuberculosis exists among cattle, and swine are kept 
on the same farm, some of the latter are tuberculous. Eradication 
of tuberculosis from cattle, it is believed, will greatly reduce its 
prevalence among swine. 
Another common practice of feeding, especially in the Corn Belt 
States is to allow hogs to run with cattle in the feed lots or pastures. 
If the cattle are tuberculous and the feces contain the germs of tuber- 
