APPENDIX II 363 



build up and repair the waste of the body, the protein may be 

 converted 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 sup- 

 ply than the carbohydrates, economy would dictate that only so 

 much 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 



Nutritive ratio. Since the protein on the one hand and the 

 carbohydrates and fat on the other, serve, in the main, different 

 purposes in the animal economy, it becomes evident that the 

 relative amounts of these nutrients in the food are important. 

 This relation is expressed as the "nutritive ratio," which means 

 the relation of digestible protein to digestible carbohydrates and 

 fat the fat having been multiplied by 2% before adding to the 

 carbohydrates, as explained above. The nutritive ratio is found 

 by dividing the carbohydrate, plus 2% times the fat, by the pro- 

 tein. In the accompanying table, No. II, the sum of the carbo- 

 hydrates and fat, thus obtained, is given in the third column, 

 which divided by the protein, as given in the second column, gives 

 the second term of the nutritive ratio in the fifth column. 



A feeding stuff having a large proportion of carbohydrates and 

 fat as compared to protein is said to have a "wide" nutritive 

 ratio, while one having a small proportion of carbohydrates and 

 fat as compared to protein has a "narrow" ratio. While these 

 terms are relative, it may be said that a ratio greater than 1 : 6 is 

 wide, while one less that 1 : 5 is narrow. The composition of feed- 

 ing stuffs, that is, the proportion in which the different nutrients 

 occur, is determined by chemical analysis, but the amount of each 

 nutrient that is actually digestible has been determined by careful 

 experiments with living animals. Only the digestible nutrients 

 are considered in the tables given in this publication. 



Feeding Standards. The amount of nutrients required, and the 

 proportions in which each should be given, vary with the kind of 

 animal and the purpose for which it is kept, whether it is grow- 



