312 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
48. A second tuberculin test shall follow each primary test 
after an interval of six months, and shall be applied in accord- 
ance with the rules and regulations mentioned. Thereafter, 
tuberculin tests shall be reapplied annually, but it is recom-. 
mended that the retests be applied semi-annually. 
49, Identification of Cows.—Each dairy cow in each of the 
certified herds shall be labeled or tagged with a number or mark 
which will permanently identify her. 
50. Herd-book Record.—Each cow in the herd shall be 
registered in a herd book, which register shall be accurately 
kept so that her entrance and departure from the herd and her 
tuberculin testing can be identified. 
51. A copy of this herd-book record shall be kept in the 
hands of the veterinarian of the medical milk commission under 
which the dairy farm is operating, and the veterinarian shall 
be made responsible for the accuracy of this record. 
52. Dates of Tuberculin Tests —The dates of the annual 
tuberculin tests shall be definitely arranged by the medical milk 
commission, and all of the results of such tests shall be recorded 
by the veterinarian and regularly reported to the secretary of 
the medical milk commission issuing the certificate. 
53. The results of all tuberculin tests shall be kept on file by 
each medical milk commission, and a copy of all such tests shall 
be made available to the American Association of Medical Milk 
Commissions for statistical purposes. 
54, The proper designated officers of the American Associa- 
tion of Medical Milk Commissions should receive copies of 
reports of all of the annual, semiannual, and other official tuber- 
culin tests which are made, and keep copies of the same on file 
and compile them annually for the use of the association. 
55. Disposition of Cows Sick with Diseases Other Than 
Tuberculosis —Cows having rheumatism, leucorrhea, inflamma- 
tion of the uterus, severe diarrhcea, or disease of the udder, or 
cows that from any other cause may be a menace to the herd, 
shall be removed from the herd, placed in a building separate 
from that which may be used for the isolation of cows with 
tuberculosis, unless such building has been properly disinfected 
since it was last used for this purpose. The milk from such cows 
