52 CITY MILK SUPPLY 



appearance arouses suspicion of the disease are discovered, reexamination 

 of the animals is made. Those exhibiting clinical symptoms are isolated 

 or slaughtered. Calves are removed promptly after birth and kept 

 separate some months when they are placed with other cattle. During 

 the period of separation the calves are fed on the milk of sound animals 

 or on the pasteurized milk of infected ones. The method is undoubtedly 

 helpful but is objected to in the United States because it amounts to 

 treating the whole herd as though it were tuberculous and because of 

 the expense attached to the frequent veterinary examinations which are 

 the vital part of the scheme of treatment. Many regard the method as 

 palliative rather than curative. 



The Bang Method of Control. The Bang system is more thorough 

 than those that have been described. The entire herd is treated with 

 tuberculin, the reactors are separated from the sound cattle and the prem- 

 ises disinfected. Doubtful cases are kept under observation and if not 

 separated from the healthy animals in the first place are so whenever there 

 is reason to believe them diseased. 



The tubercular animals are preferably kept in a separate building on a 

 part of the farm away from the sound stock but where necessity compels, 

 they may be kept in a part of the barn containing the others, if they are 

 walled off so completely that there is no possible communication between 

 the two. The sick and the well animals are pastured separately. Owing 

 to the ease with which manure and other infectious material may be trans- 

 ferred from one herd to another separate attendants for the two parts of 

 the herd should be provided if it can be afforded. The reacting and non- 

 reacting cattle should not have the same watering troughs. 



Cows that have tuberculosis of the udder are slaughtered. Calves 

 that are dropped by tubercular mothers are taken away before they have 

 a chance to suck and are raised on the milk of sound cows or on milk of 

 the tubercular stock pasteurized at 176F. Experience has taught that 

 calves are, with but rare exceptions, born free from tuberculosis. The 

 rearing of calves from advanced cases is not encouraged for the few cases 

 of intra-uterine infection that do occur most often arise in the progeny of 

 such cows. The whole stock including the calves is retested every half 

 year, reactors removed and necessary disinfection attended to. Ulti- 

 mately a sound herd is built up, and the diseased stock out of which it 

 came is slaughtered. 



The advantages of the system are: (1) It is efficient, for by its use a 

 tuberculosis-free herd can be obtained in from 1 to 3 years though some- 

 times 6 to 8 years are required in a badly infected herd. (2) The initial 

 expense is not great. (3) It does not disturb trade. (4) Owners and 

 herdsmen obtain thorough knowledge of the disease, an acquisition of 

 inestimable value to them. The disadvantages are: (1) Extra labor is 

 required. (2) Great vigilance is exacted for any laxity will undo the work 



