366 IOWA DEPARTMENT OP AGRICULTURE. 



disease is caused by infection of dairy products containing the tubercle 

 bacilli. Instances are common where droves of hogs, which at some time 

 in their lives had been fed whole milk, skim milk or buttermilk, when 

 slaughtered, showed a large proportion of the number to be infected with 

 tuberculosis. This is proved by the fact that tuberculosis prevails mostly 

 where the dairy industry is the most extensive, namely, northern Ger- 

 many and Denmark. It is a difficult matter to find hogs raised under 

 common farm conditions that have not been at some time in their lives 

 fed cow's milk. It is thus apparent that the consensus of opinion has 

 some foundation when it is generally believed that cow's milk is re- 

 sponsible for the rapid spread of this disease to the swine herds of the 

 country. 



"The subjecting of milk intended for hog feeding to 176 degrees of 

 heat, or 'pasteurization,' to kill any tubercle bacilli that might be present 

 is now a common practice on the modern dairy farm and at the leading 

 creameries. There is a desire with many to know whether there is any 

 practical necessity of this pasteurization in this State. The only answer 

 to the question is the results of actual experimental investigations into 

 the transmissibility of the disease to hogs from cow's milk." 



An experiment in feeding pasteurized milk to two separate lots of 

 pigs and milk infected with tuberculosis germs to two other lots was 

 carried on for a period of about eight months. The pigs at the beginning 

 were free from tuberculosis. Of the twenty pigs fed infected milk every 

 one was found upon slaughter to have acquired disease of tuberculosis, 

 while of the twenty pigs fed on pasteurized milk only two showed slight 

 traces of the disease. 



The swine industry in this State is of such great importance that every 

 effort ought to be made to protect it from loss by disease. The pasteuriza- 

 tion of skimmed milk at the creamery, as shown by the foregoing experi- 

 ment, is effective in preventing the spread of tuberculosis among swine. 

 For a creamery to refuse to obey the law requiring such pasteurization 

 is to disregard the interests of the whole community, and those of the 

 patrons of the creamery in particular. A considerable number of prose- 

 cutions has been undertaken in cases where the creameries have not been 

 pasteurizing the skimmed milk. The matter is of such very great im- 

 portance that this department will continue to make prosecutions for 

 failure to comply with this statute wherever it is possible to secure evi- 

 dence of such violation. 



During the year there have been fines inflicted for violation of the 

 statute in relation to the pasteurization of skimmed milk upon creamery 

 managers at Ackley, Harlan, Bristow, Ladora and Ottoson. 



BUTTER PRICES. 



Below is given a table showing New York prices on butter of the high- 

 est grade by months for the last eleven years. The average price for 

 1896 was about the same as that for 1897 given below and these two years 

 mark the lowest prices for butter in the last twenty years. 



