DAIRY CATTLE 



479 



curdle in 18 hours, while the same milk 

 kept at 70° F. will not curdle until af- 

 ter 48 hours, and at 50° F. may not 

 curdle for two weeks. Conn has, there- 

 fore, called attention to the fact thac 

 the keeping quality of the milk depends 

 more intimately upon the temperature 

 at which the milk is kept than upon the 

 original contamination of the milk with 

 filth and bacteria. The use of refriger- 

 ation, however, should not be allowed as 

 a means of preventing the bad results of 

 filthy habits in milking. 



Formalin as a preservative of milk — 

 Special attention is called to formalin 

 as a milk preservative for the reason thai 

 this chemical has recently been used more 

 extensively than any other for the pur- 

 pose of preventing the souring of milk, 

 and the development of bacteria in it. 

 Numerous experiments with it have been 

 carried on by European investigators 

 and by the United States Department of 

 Agriculture and agricultural experi- 

 ment stations in the different states. It 

 has been shown by Chester, that bacteria 

 diminish rapidly in milk when it con- 

 tains formalin at the rate of one part in 

 2,000. Even when formalin was added 

 only to the extent of one part in 4,000 

 the multiplication of bacteria was much 

 less rapid than in the case of untreated 

 milk. Chester believes that the use of 

 1 teaspoonful of 40 per cent formalin for 

 each 15 gallons of milk will improve the 

 sanitary condition of the milk by pre- 

 venting fermentation without causing 

 any marked harm to persons who con- 

 sume the milk. As already stated under 

 the discussion of Beef Animals, Klein 

 and others have found that the use of 

 formalin in milk fed to calves may be 

 depended upon to prevent or cure scours. 

 The action of the formalin is obviously 

 the same in this case as when used sim- 

 ply for preventing the fermentation of 

 milk. Moreover, Von Behring recom- 

 mends the addition of formalin at the 

 rate of one part to 20,000 to 40,000 parts 

 of milk in order to destroy tubercle 

 bacilli in the milk. The whole question 

 of the use of preservatives, however, is 

 at present subject to a bitter controversy 

 and until some of the doubtful point3 

 are settled regarding their use, it seems 

 best to recommend against the use of 

 any preservative in milk, for the reason 

 that by the exercise of due care milk 

 can be obtained which will keep long 

 enough for the purposes of the ordinary 

 consumer. 



Babcock milk test — The only means 

 of knowing the productivity of each 

 cow consists in weighing the milk and 

 testing it from time to time for fat con- 

 tent. Reliable spring scales are inex- 

 pensive and may be hung in positions 

 so that the time occupied in weighing 

 the milk of each cow is exceeding slight. 

 The percentage of butter fat should also 

 be tested once a month or oftener. The 

 best and simplest apparatus for deter- 

 mining the percentage of fat in milk 

 is the Babcock tester. In making the 

 test, the milk to be tested should be thor- 

 oughly shaken so as to obtain a fair, 

 average sample. The samples from dif- 

 ferent cows are then mixed with strong 

 sulphuric acid in Babcock test bottles 

 and whirled at the rate of 850 to 1,000 

 revolutions a minute in the Babcock 

 tester for about five minutes. The con- 

 tents of each bottle should be well 

 shaken before whirling in the tester and 

 immediately after adding the sulphuric 

 acid. The action of the acid is to digest 

 the protein of the milk and set free the 

 fat, which readily separates from the 

 Test of the milk. After the machine has 

 been whirled for five minutes it is 

 stopped and pure hot water, preferably 

 distilled water, is added so as to fill the 

 bottles up to the neck. The machine is 

 then whirled again for two minutes and 

 hot water again added until the fat 

 rises in the neck of the bottle, where 

 the percentage may be read on a gradu- 

 ated scale. The machine is again 

 whirled for a minute to make sure that 

 all the fat is separated, and the tempera- 

 ture of the milk at this time should 

 preferably range between 120° and 140° 

 F. If too much acid is used or the milk 

 is too warm at the time when the acid 

 is added, some of the fat may be 

 charred; on the other hand, if too little 

 acid is used, white flocculent material 

 may appear at the lower end of the fat 

 column; again, if the water is impure 

 or hard, there may be a mass of foam at 

 the top of the fat column. The reading 

 of the percentage of fat is a simple mat- 

 ter, which may be done very accurately 

 after a little experience has been had. 



Creaming of milk — After the milk 

 has been somewhat cooled by the use of 

 a cooler, or some other cooling device, it 

 may be set in shallow or deep pans for 

 the separation of the milk by gravity; or 

 the milk may be run through a separator 

 without any preliminary cooling. There 

 are. therefore, two general systems of 



