DAIRYING 41 



not have any serious effect on the health of the cow, and it has 

 been found that the effect if any on the milk flow is temporary. 

 Bohm*** reports that with reacting cows there was a falling off in 

 milk within two or three days after injection, but a return. to normal 

 milk yield within one week. In non-reacting cows there was no 

 diminution in the milk yields. 



Trials made by de Schweinitz**** showed that when large doses, 

 30 cc. of tuberculin, were injected into healthy cows there was 

 no variation in the fat in the milk, but with some reacting cows "a 

 marked decrease in fat was noted." The data collected indicates 

 that the testing of cows by injection of tuberculin into' the circula- 

 tion has no serious effect on the milk secretion. 



U. Sickness of a Cow. 



199. Any disturbance of a cow's digestion which is sufficient 

 to cause her to refuse to eat, or the appearance of a feverish con- 

 dition as well as the occurrence of a more serious sickness has an 

 influence on milk secretion. The most common change in the milk 

 is a decrease in the amount, and an increase in the per cent of fat. 

 If the milk of cow is being tested at each milking, and a sudden 

 increase in fat is noticed at any one milking, this is a good indica- 

 tion of some disturbance of the health of the cow provided nothing 

 else, like the breaking loose of some cow in the stable at night, has 

 happened. The" per cent of fat in milk varies more than the other 

 constituents of milk and although severe sickness may change the 

 entire composition of a cow's milk, the per cent, of fat is subject to 

 so much variation from one milking to another that the old idea 

 of feeding a baby with the milk of one cow only, is no longer 

 considered advisable. 



The mixed milk from several cows is much more uniform in 

 composition from day to day than that of one cow, as the entire 

 herd of cows is not likely to be influenced by the same disturbance 

 that may effect one or more cows in the herd. 



V. Protection from Flies. 



200. Many remedies have been proposed for keeping the flies 

 away from cows, and a number of trials have been made to note 



***E. S. R. xx 85. 

 **** B. A. I. 13. 



