70 STATE BOARD OF AGRICULTURE 



can and will spread cannot be gainsaid. The history of the college herd 

 illustrates this single point, for, since its incipiency, it has become more 

 and more difficult to cope with, until the use of tuberculin began in 189(i. 



Laboratory work on the thermal-death point of the tubercle bacillus 

 has been carried on for the sole purpose of establishing whether pasteur- 

 ization at 70° C. for twenty minutes is sufficient to kill the germ which 

 causes the dreaded "white plague." The experiments demonstrate con- 

 clusively that such treatment will kill the tubercle bacillus if the pas- 

 teurization is properly done. Stress is placed upon the care necessary 

 for proper pasteurization. The results of tbese experiments have been 

 published in bulletin form. To the above might be added with advantage 

 the method now in general use in Denmark. The milk or the cream from 

 which butter is made is heated momentarily to 85°-95° C, and then the 

 milk is suddenly cooled down to 10° C. The sudden cooling seems to 

 have a marked effect on the value of the butter. I quote from a free 

 translation by Mr. C. W. Sorensen, a dairy expert: "In the prompt and 

 thorough cooling of the cream lies the crux of the whole question. Even 

 95° C. was repeatedly employed without any permanent cooked flavor 

 being at all noticeable, so long as the cooling was efficient. Although 

 the butter had a slight peculiar flavor when first made, this invariably 

 disappeared in the course of one or two days. Comparisons between but- 

 ter made from milk or cream pasteurized at 85° C.-90° C. and from por- 

 tions of the same cream heated only to 72° C. showed that not only was 

 the former as good, but, in many cases, was better than the latter. The 

 cooling is as important as the heating itself." * * * "While on the 

 subject, it may be interesting to know^ that out of the 713 factories com- 

 peting last year in the Danish 'State Butter Shows,' all except five pas- 

 teurized the whole of their output^ — four of these five had the unenviable 

 distinction of occupying the four bottom places in the official list, while 

 the fifth was not much better— and all but eleven used 'commercial 

 starters.' " — (Written for the New Zealand Dairyman and Dairy Mes- 

 senger.) Mr. Sorensen further states that these Danish experiments ex- 

 tended over all seasons of the year, were carried on in four different lo- 

 calities and constituted fifty-two distinct experiments by the scientific 

 experts of the experimental school of agriculture. These remarks are 

 inserted to show that the great cry against pasteurization is without 

 foundation, for Danish butter is first on the London market, and also that 

 it is not necessary to hold to 70° C. for twenty minutes in the pasteuriza- 

 tion of cream for the making of butter, but the temperature may be as 

 high as 90° C. without danger to the quality of the butter. However, the 

 cooked flavor of the milk is quite perceptible at this temperature and does 

 not disappear, as in the case of butter. 



The investigations of Michigan milk for tubercle bacilli continue. 

 Many obstacles are met with in securing fair samples, consequently this 

 line of work may be prolonged for some time. The object of these tests 

 is to gain some idea of the infectiousness of Michigan milk from tubercu- 

 losis by selecting fair samples from various parts of the State and sub- 

 jecting them to a bacteriological examination upon animals. The micro- 

 scope will not be depended upon, because of its unreliability in such exam- 

 inations. 



During the past year many weeks of my time and energy have been 

 expended upon the study of the so-called hog-cholera as it occurs in Mich- 

 igan. This disease probably causes more financial loss than any other 



