120 The Farmer's Business Handbook 



it more correctly implies a certain class of protein 

 substances. The function of protein in the food 

 is, first of all, to build up and repair the working 

 machinery of the body, and to supply protein 

 for the production of milk, wool, etc. No other 

 food constituent can fulfil this function. 



The importance of a sufficient supply of protein 

 in the ration is, therefore, apparent. If in excess 

 of the amount required to build up and repair 

 the waste of the body the protein may be con- 

 verted into fat and deposited as such or used to 

 produce heat and energy. Its efficiency for these 

 purposes is about the same as the carbohydrates, 

 but as it is usually far more expensive to supply 

 than the carbohydrates, economy would dictate 

 that only so much protein should be supplied to 

 the animal as will suffice to repair the wastes of 

 the animal machinery and build up new growth in 

 case of growing animals, or for the production 

 of milk, wool, etc. 



Compounding of Rations. — a. Nutritive ratio. — 

 Since the protein on the one hand and the carbo- 

 hydrates and fat on the other, serve, in the main, 

 different purposes in the animal economy, it be- 

 comes evident that the relative amounts of these 

 nutrients in the food are important. This rela- 

 tion is expressed as the "nutritive ratio," which 

 means the relation of digestible protein to digesti- 

 ble carbohydrates and fat — the fat having been 



