288 .AGRICULTURAL BACTERIOLOGY 



tions, which should be kept in separate quarters and pas- 

 tures. The calves from tubercular animals should be re- 

 moved at birth, placed with the healthy portion of the herd, 

 and fed on the milk of healthy animals, or on that of the 

 tubercular animals after proper sterilization. In almost all 

 cases, calves so treated can be raised to maturity in a 

 healthy condition. As the herd is built up in this way, the 

 old reacting animals can be discarded; by this means the 

 valuable characteristics of the particular family can be 

 transmitted through the progeny. This method of "weed- 

 ing out" the disease, instead of "stamping" it out by whole- 

 sale slaughter, is known as the Bang system, and has been 

 widely used in Denmark, where the percentage of affected 

 animals is so high that immediate slaughter would be almost 

 prohibitive. 



If 50 per cent, or more of the animals react to the test, 

 it is advisable to consider the entire herd as infected, and 

 not attempt to eradicate by separation and slaughter, but 

 to build up the healthy herd by the progeny alone. This 

 plan is recommended because it has been found by experi- 

 ence that when so large a part of the herd reacts to the test, 

 most of the remaining animals will react later. 



Many of the States require the removal of known tuber- 

 cular animals from dairy herds. In most cases the State 

 bears a part of the loss by compensating the owner in part 

 for diseased or reacting animals. The reacting cattle are 

 usually slaughtered at some abattoir in which federal in- 

 spectors are stationed. The meat of reacting animals may 

 or may not be passed as fit for food, depending upon the 

 extent of the lesions of the disease. It was formerly the 

 custom to destroy all carcasses of reacting animals, but this 

 economic loss is no longer sanctioned. In the incipient 

 stages of the disease the affected parts are usually confined 

 to definite organs, and if those are removed, no danger 



