276 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



whey. Such a process is compulsory in Denmark. Minnesota and 

 Iowa also have laws requiring these by-products to be heated. The 

 heating of skim milk and whey can be done with inexpensive ap- 

 paratus. Most frequently it is accomplished by the injection of 

 steam. In those states requiring the treatment of these .by-products, 

 the laws provide that they shall be heated to 176 degrees F., since at 

 this temperature milk and whey undergo a change that can be 

 readily detected by the inspector, whose duty it is to determine 

 whether the law is being obeyed. 



A lower temperature will, however, destroy tubercle bacilli. 

 If skim milk or whey is heated to 155 degrees F. and allowed to 

 cool slowly all tubercle bacilli will be killed. If it is desired to 

 have buttermilk free from such disease bacteria, the cream must 

 be pasturized before churning. Heating the buttermilk causes the 

 curd to settle and makes the buttermilk difficult to handle. 



The heating of whey and skim milk is desirable since it in- 

 sures the return of these products in a sweet condition to the farm. 

 Such material has a higher feeding value than sour fermented 

 by-products. The treatment has also been found to be of great 

 service in improving the quality of the milk, since the cans do 

 not become contaminated with harmful bacteria which may find 

 their way into the milk supply when the cans are poorly washed. 

 The process of heating whey is being rapidly introduced in Canada 

 for the purpose of improving the quality of milk. 



The use of the farm separator also overcomes the danger of 

 introducing tuberculosis from factory by-products, as in this way 

 the milk of the home herd alone is fed. The creamery separator 

 slime should never be used as feed. It should be burned. 



Why Does the Farmer so Frequently Fail to Appreciate the 

 Danger From Tuberculosis? Every farmer is afraid of hog chol- 

 era because it quickly causes large losses. It appears, destroys 

 the majority of the herd, and disappears. Tuberculosis causes 

 greater loss, but attracts little attention, because it develops slowly 

 in the animal, and may require years to produce death. The ani- 

 mals decline so slowly that it seems as though some inevitable, un- 

 preventable trouble were present. So human tuberculosis used to 

 be considered. Now, however, it is looked upon 'as preventable 

 and curable. 



How Can Tuberculosis Be Detected? A physical examination 

 of a tubercular animal fails to reveal any characteristic symptoms 

 that permit of the detection of the disease except in the later stages 

 and the only way in which the presence of tuberculosis can be de- 

 tected with certainty in all stages in the living animal is by the tu- 

 berculin test. 



THE TUBERCULIN TEST, ITS MODE OF APPLICATION AND INTERPRE- 

 TATION. 



What is the Tuberculin Test? If a tuberculous cow has a 

 small quantity of tuberculin introduced beneath the skin, a tem- 

 porary fever will result, which can be detected by taking the tem- 

 perature of the animal; a healthy animal shows no such fever. 



