ANIMAL PRODUCTS 



277 



the milker and fall into the milk. Mi- 

 cro-organisms may also gain entrance to 

 the milk with dirt from the ceilings of 

 the stable. 



The air of most stables carries con- 

 siderable dust contaminated with bac- 

 teria. The dust may come from the 

 hay or other feed, from the bedding, 

 from soil carried in on the cows' feet 

 or from dried manure. Some dairymen 

 allow their cattle to wallow in filthy 

 yards and the legs and flanks of the cows 

 rnay become plastered over with filth. 



The milk vessels unless cleaned with 

 live steam or thoroughly washed with 

 boiling water are almost sure to contain 

 large numbers of bacteria in connec- 

 tion with dried particles of milk fat or 

 sediments in the cracks of the vessels. 

 Under ordinary conditions this is al- 

 ways an important source of milk con- 

 tamination. The water used in wash- 

 ing the milk vessels may be a source of 

 bacteria and may carry typhoid. 



The milker — In the bacterial con- 

 tamination of milk the milker may be an 

 important factor. His hands or clothes 

 may be soiled or he may have insani- 

 tary habits. If typhoid, scarlet fever, or 

 diphtheria should prevail in the family 

 of the milker he may carry these dis- 

 eases to the milk and thus transmit 

 them to his patrons. 



Dangers from milk itself — Milk is 

 an excellent medium for the growth of 

 bacteria and many of them multiply rap- 

 idly in it. Obviously, therefore, milk 

 varies greatly in its bacterial content 

 when it reaches the consumer. The ac- 

 tual number of bacteria may vary from 

 1,000 to several million per cubic centi- 

 meter of milk. Fresh milk drawn un- 

 der cleanly conditions should not con- 

 tain more than 2,000 to 3,000 bacteria 

 per cubic centimeter. If it contains as 

 high as 20,000 per cubic centimeter, 

 some of. the precautions of cleanliness 

 have been neglected. Naturally, the 

 number of bacteria is higher in summer 

 than in winter, but occasionally runs up 

 to 100,000,000 per cubic centimeter in city 

 milk. It is difficult to establish a legal 

 standard for the bacterial content of milk. 

 It should not contain more than 10,000 

 per cubic centimeter, and some dairies 

 guarantee to keep it below that figure. 



Abnormal conditions in milk — Some 

 of the abnormal conditions of milk due 

 to bacteria may now be briefly men- 

 tioned. Bitter milk may be the result 

 of eating lupine, ragweed, or other 

 weeds, or may be produced by certain 



kinds of bacteria. The bitter taste may 

 develop in fresh milk, sterilized milk or 

 in cheese. Slimy milk is a common trou- 

 ble in the dairy. It may be due to an 

 improper ration, to the existence of gar- 

 get in the udder or to bacteria, usually 

 to the last named cause. Ropy milk or 

 cream emphasizes the necessity of scald- 

 ing or otherwise sterilizing all milk 

 utensils. Soapy milk, characterized by 

 frothing and a peculiar soapy taste of 

 the milk, is a rare abnormality due to a 

 specific bacillus which occurs on hay or 

 straw. Blue milk is due to the presence 

 of Bacillus cyanogenes in the milk. Red 

 milk is sometimes observed as the re- 

 sult of the growth of Bacillus erythro- 

 genes. It may also be due to garget or 

 to feeding on certain plants. 



Prevention of bacterial contamination 

 — From the above discussion the desi- 

 rability of reducing bacterial contamin- 

 ation is sufficiently obvious. This may 

 best be accomplished by cleanliness and 

 by keeping the milk cool. The cows 

 must be regularly groomed, so that dirt 

 and hair will not fall into the pail at 

 milking time. No dust should be al- 

 lowed in the milking stable. The floors, 

 walls and ceiling should be washed. The 

 yard in which the cows stand should be 

 dry and the water supply pure. Milkers 

 should have cleanly habits, wear clean 

 clothes — a special suit exclusively for 

 milking, if convenient ■ — and should 

 never go directly from a sick room to 

 the cows. Milk vessels cannot be washed 

 too clean and are usually not given 

 enough attention. The water used about 

 the milk room and for washing must be 

 known to be pure and wholesome. In 

 milking, covered milk pails should be 

 used to prevent the dirt from falling in- 

 to the milk. As soon as it is drawn the 

 milk should be taken away from the 

 stable so as not to absorb any bad odors. 

 It should then be immediately cooled, 

 aerated and kept cool, as is described 

 under Dairying. The reason for keep- 

 ing milk cool is that the multiplication 

 of bacteria is thereby greatly retarded 

 and souring postponed to a correspond- 

 ing degree. 



Transmission of diseases in milk — 

 The inspector on his rounds takes note of 

 all these matters — the health of the cows, 

 kind and quality of feeding stuffs, condi- 

 tion of stables and premises, milking 

 methods, health and habits of the attend- 

 ants, care of dairy utensils, etc. His is 

 an important and responsible position. 

 Physicians have traced a considerable 



