CHAPTER XI 



MILK PRODUCTION 



THE production of milk by cows is influenced, both as 

 to quality and quantity, by many different circumstances. 

 These fall, for the most part, to be considered under the 

 chemistry of dairying. The present chapter deals with the 

 question only so far as the food of the animal is con- 

 cerned. 



It is clear at the outset that the cow cannot produce milk 

 out of nothing. All that it can do is to transform the con- 

 stituents of the food into the constituents of milk. It has 

 been shown in previous chapters that each animal requires a 

 certain minimum ration for maintenance. This food under- 

 goes oxidisation. The products are given off from the 

 animal's body in the form of carbon dioxide, water, urea, etc., 

 and the resulting energy (heat) is dissipated in various ways. 

 If any part of this food is not oxidised, but turned into milk, 

 or used in any other way, the remainder will be inadequate 

 for the sustenance of the animal, which will, therefore, lose 

 weight. If milk is to be produced, and the weight of the 

 animal maintained, the constituents of the milk must be 

 derived from other sources, i.e. from additional food supplied 

 for the purpose. The nature and quantity of this additional 

 food must correspond in some degree to the composition and 

 quantity of the milk produced. A primary indication of 

 the requirements may, therefore, be obtained from a study 

 of the milk itself. 



Milk. The composition of cow's milk is subject to con- 

 siderable variation from causes which need not now be 



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