XIV.] FOOD REQUIRED BY cows 281 



amount required for the production of the milk she 

 yields, which may be taken to bear approximately the 

 same relation to the food as the live weight increase 

 does in the case of the fattening animals. For practical 

 purposes considerable economy can be effected in the 

 feeding of the herd if the cows are divided into three or 

 four groups, according to their weight and their milk 

 yield. The cows should have first a basal ration, supply- 

 ing each with about 25 lb. of dry food per 1000 lb. 

 live weight, this food to contain about i lb. of digestible 

 protein and J lb. digestible fat. Next, for each 10 lb. of 

 milk, food with a starch equivalent of about 5 J lb. and 

 containing about \\ lb. of protein, is necessary. The 

 cows can easily be divided into three groups according 

 to their milk yields (allowing also a little for their live 

 weight), and given one, two, or three measures of con- 

 centrated food in addition to the basal ration which all 

 receive alike. 



Butter 



The essential feature of butter-making consists in 

 agitating either the whole milk or the cream until the 

 fat globules coalesce and form clots the size of shot, at 

 which stage the butter is said to have " come." Whole 

 milk is very rarely churned nowadays; instead, the milk 

 is first of all set for twenty-four or forty-eight hours and 

 the cream skimmed off, or the cream is separated by 

 some mechanical separator, as in all modern dairies. 

 In the old-fashioned methods of making butter, the 

 milk, when still warm, is poured into shallow pans, which 

 are left to stand in a cool dairy, whereupon the fat 

 globules slowly rise to the surface, and the layer of 

 cream is skimmed off] The separation, when effected 

 in this way, is not very perfect, about 0-8 per cent, of the 

 fat being left in the skimmed milk. Instead of shallow 



