244 IOWA DEPARTMENT OF AGRICULTURE 
any environment. All cattle should be kept in well lighted barns. 
Light destroys all germs and it will destroy tubercular germs. You 
should also have plenty of ventilation. There is a system of ventila- 
tion used by poultry men which is very good. They use canvass 
on doors and windows. I think it could be used in cattle and horse 
barns. At the college we take a piece of ordinary nine or ten cent 
cloth and tack it over the window. There will be no draft, but still 
plenty of ventilation. If you go into a barn like that there is not 
that stuffy condition and many dairy men are using that kind of 
ventilation. Every cow should have from six hundred to a thou- 
sand feet of air space. If you have a high ceiling you will have 
plenty of air space without a draft. The coavs should not stand 
with their heads together. If a cow has open tuberculosis or coughs 
it out she will infect other cows that stand on either side. As far 
as ventilation is concerned it does modify the course of the disease 
in herds where there is tuberculosis, but it will not absolutely pre- 
vent other animals from getting it and the sane thing for you to do 
is to test your cattle. As to the manner of applying the test. It 
has been advocated that the farmer can apply this as well as the 
veterinarian. Probably he can. You could go into a court room 
and plead your o\Yn case or you might be your own doctor or do 
your own preaching, but we usually employ some one who is skilled 
along those lines because they can do it so much better than Ave 
can, so I think an experienced man should be employed to do this 
work. You cannot free your herd by one test. Some herds where 
you find one or two cows that have tuberculosis in a form where 
they do not discharge germs you can do that, but you never know 
when you have a case of tuberculosis and for that reason you should 
test your herd and remove all those animals and then retest them. 
They should be tested twice a year. It is better in the fall than in 
the spring. Every animal having tubercular germs does not have 
tuberculosis. That has been demonstrated, that an animal may 
take in tubercular germs and drop those germs without being 
affected. Iowa stock men will have to get hold of some plan for 
testing their herds, for I don 't think you can use the Bang system. 
It is this, that you test your cattle, put your tubercular cattle by 
themselves, have your safe herd and quarantine herd. It takes 
to much time and the farmer can't have the attendants necessary. 
You must either test your cattle and condemn them or test them 
and keep them away. Take the calves out, test them, and put them 
by themselves for three months and at the end of the three months 
