HOUSING AND CARE OF COWS 95 



■water, and sprinkled when very dusty. Children and cats and dogs 

 must be excluded from the barn at milking time. 



The essentials in relation to the stable, then, are: Sufficient 

 pure air and light; freedom from dust; clean floors, gutters, walls 

 and ceilings ; and clean surroundings, free from manure and rubbish. 



Care of the Cows* 



All cows should be tested with tuberculin-j- before their milk is 

 used for human consumption, either as raw milk or in the form of 

 cream, butter or cheese. This is necessary, since no expert can 

 tell positively by the appearance or examination of a cow whether 

 she is tuberculous or not in many cases. A tuberculous cow 

 may even be very fat. If tuberculous cows are found in the stable 

 it must be thoroughly cleaned and disinfected after the diseased 

 cows are removed and before healthy animals are placed in the stable 

 (see p. 346). 



Before adding new cows to a herd it is safer to test them with 

 tuberculin twice; once before purchase and again after three months 

 of isolation from the herd. Then if the cows fail to react they may 

 with safety be added to the herd. Sometimes cows which fail to 

 react in the first test may communicate the disease to the herd if 

 at once turned loose with the herd before a second test. The neces- 

 sity for this double test with tuberculin depends upon the fact that 

 animals may not react in a very early or latent stage of tuberculosis 

 and again that animals receiving treatment with tuberculin in in- 

 creasing doses before their sale may not at that time react to an 

 ordinary test dose. New cows subject to the double tuberculin test 

 and isolated may still supply certified milk after the first negative 



test. 



The germs of tuberculosis have been frequently found in milk, 

 cream, cheese and butter. (Butter may harbor active tubercle bacilli 

 for five or six weeks.) The bacilli of tuberculosis will retain their 



* See Moak's " Card for Identifying Cattle," p. 357. 



f For directions for testing cows with tuberculin, see p. 347. 



