LIVE-STOCK AND DAIRYING. 381 



these materials, as well as skim milk> are used for feed- 

 ing farm animals, especially calves, pigs or poultry. 



Care of Milk. Milk is a very unstable product, and 

 unless special precautions are taken it will turn sour 

 within twenty-four hours, if kept at ordinary tempera- 

 ture. This is due to the presence therein of bacteria. 

 These are microscopic plants which get into the milk 

 through dust in the barn and from other sources, and 

 begin to multiply in the milk shortly after it is drawn; 

 through their life-processes they break down the sugar 

 of the milk into lactic acid. When a certain acidity 

 has been reached (over 0.3 of one per cent.) the milk 

 will taste and smell sour, and if the acidity exceeds 0.75 



PROGENY DF R 

 SINGLE DERM 

 IN TWELVE HOURS 



COOLING MILK PREVENTS THE RAPID GROWTH OF BACTERIA. 



of one per cent., it will curdle (coagulate). Any 

 means of precaution that will prevent the infection of 

 the milk or check the growth of bacteria therein will 

 tend to increase the keeping quality of the milk. As 

 bacteria are abundantly present in all kinds of dirt, 

 cleanliness is a most important factor in preventing the 

 souring of milk. Milk pails, glass bottles, and other 

 utensils in which milk is kept must be scrupulously 

 clean. Another factor is cooling the milk to a low 

 temperature (below 40 F. if practicable), and keep- 

 ing it at this temperature until consumed. Bacteria 

 grow very slowly or not at all at low temperatures. 



