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Wisconsin Dairymen's Association.
TUBERCULIN AND ITS USES.
PROF. E. G. HAsTINGS, COLLEGE OF AGRICULTURE, MADISON, WIs.
The tuberculin test has been in practical use for twenty years. Dur-
ing this interval thousands of herds have been examined for tuber-
culosis, and the practical value of the test has been shown in freeing
many of these herds from this disease. By the aid of the test, countries
have been able not only to stop the spread of tuberculosis, but even
to diminish the amount of this most important disease among their
herds. The other methods which have been and are still used to some
extent for the diagnosis of tuberculosis in cattle are of minor signifi-
cance when compared with the tuberculin test. It would not be too
much to say that without it we should be practically helpless against
the spread of tuberculosis in cattle.
It would seem that during the twenty years the test has been in
practical use all of the important points concerning its application
should have been learned. It is very certain, however, that we have
yet much to learn about it. Important information has been gained
concerning it in the last few years, and it is to this that I should like
to cal your attention to-day.
The breeder and dairyman has often been led to believe that- the
tuberculin test Is an infallible means by which he can detect the
presence of the disease in his herd; that by its use he can remove
every tubercular animal from the herd and no healthy animal. Ex-
perience has shown otherwise. A freqaent experience has been some-
what as follows: A herd of cattle was tested, and a considerable
number of the animals were found to be diseased. These were re-
moved, the stable was thoroughly disinfected, and a retest made
within three to six months, at which time but one or two animals
might react to the test. Another test was made a year thereafter
and possibly a considerable number of reacting animals was then
found. At another test a year later, tuberculosis might still be found
to be present in the herd. In many cases the farmer became dis-
souraged because of such results. He felt that it was impossible to
free his herd from this disease, and he abandoned the idea of ever
being able to obtain a healthy herd from the diseased foundation. In
the past the blame for such results has been laid on inefficient testing
or on faulty barn disinfection.  Another experience which has been
frequently brought to the attention of the sanitary authorities has
been that a herd was tested, the reacting animals all removed, and
soon thereafter, for some reason or other, one of the supposed all
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