Genital hifedioyis of Cattle as an Economic Problem 709 



the young, continues its destruction. The United States De- 

 partment of Agriculture has made the estimate that the 

 phenomenon of abortion costs the nation twenty million 

 dollars annually. The dairy cow, in order to yield the maxi- 

 mum amount and quality of milk, should give birth to one 

 healthy calf each twelve months. The purebred herds drop 

 to between 50 and 75 per cent, of this ideal during an ap- 

 pallingly brief breeding career. Including all cattle of 

 dairy breeds, the reproductive efficiency does not exceed one 

 calf in each fourteen months, so that each cow is kept upon 

 an average two functionless months. If the loss is rated at 

 five dollars per cow per month, the 1,500,000 cows in the 

 State of New York alone aggregate an annual loss, due to 

 delay in conception, of $15,000,000. That is but one item of 

 loss. When the total losses are considered, the sum is many 

 times the one item noted, making this easily the most de- 

 structive group of infections of cattle. The statement is 

 now and then made that, next to tuberculosis, "contagious 

 abortion" is the most destructive disease of cattle. That con- 

 clusion is based, if not wholly, at least chiefly, upon the ob- 

 served expulsion of the fetal cadaver and technically re- 

 stricted to the damage alleged to be inflicted by B. abortus. 



E. The Genital Infections of Cattle in Their 

 Relation to Human Health. 



Milk and its derivatives constitute the most important 

 food of the human race. Milk has been clearly shown to be 

 a dangerous carrier of infections, such as scarlatina, ty- 

 phoid fever, putrid sore throat, and others. These are 

 largely contaminations occurring outside the udder. After 

 Koch had discovered the tubercle bacillus and thought bo- 

 vine and human tuberculosis identical, it was believed for 

 some years that much human tuberculosis was due directly 

 to the use of milk from tubercular cows. Later researches 

 have modified that view, and, while still considered as of 

 essential importance to human health, bovine tuberculosis 

 is not thought to be as perilous for man as it was at an 

 earlier date. More recently, following the discovery of the 



