Experiments with Tuberculin. 665 



PERCENTAGE OF BUTTER-FATS IN THE MILK. 



Before dismissing the .milk it is desirable to consider how the 

 ratio of butter-fats is affected by repeated test doses of tuberculin 

 injected into a healthy animal. A study of the tables given below 

 will fail to establish any connection between the presence of a test 

 dose of the tuberculin in the animal body, and any increa.se or 

 diminution of the fat in the milk. The Holstein Belva had her 

 highest percentage of butter-fat (3.6) October 20th, ten days be- 

 fore the first injection of tuberculin. Her next highest record 

 (3.4) was Dec. 8th while under the action of tuberculin. Her 

 lowest record (2.8) was Dec. ist, two days after the operation of 

 a dose of tuberculin. Her variation (0.8) is only a little more 

 than that of the untreated cow Freda (0.6), and only about half 

 that of Molly (1.5). The Jersey Daisy also made her highest per- 

 centage (5.6) October 20th and her lowest (4-8) December 8th 

 when under the action of tuberculin. But she made her second 

 highest (5.55) Nov. loth when under tuberculin and an equal 

 record Nov. 17th two days after the operation of a dose of tuber- 

 culin. Her greatest variation was 0.7 per cent., whereas, that of 

 the untreated cow Bertha, was 1.15 per cent. 



There is therefore no change in the percentage of butter-fats 

 sufficient to indicate any disease or ill-health as the result of the 

 administration of repeated test doses of tuberculin. 



EFFECT ON BODY WEIGHT. 



The weight of the animals varied so little during the experi- 

 ment that it might be said to ha\'e remained stationary. The re- 

 cord is as follows : 



October 30th. 

 Belva, 1264 lbs., 

 Mabel, 1455 " 

 Daisy, 945 " 

 Short Grade Horn, 

 Grade Devon, 



Considering that a variation of 50 lbs. in the weight of a cow 



may occur in a few hours according as it is taken before or after 



feeding and watering or milking, there may be said to have been 



no change excepting in the case of the two Holsteins in which 



