160 FIRST PRINCIPLES OF AGRICULTURE. 



compounds given by the standard can be followed with 

 great advantage. In many cases, too, while the propor- 

 tions given by the standards would furnish the greatest 

 return for the amount fed, other proportions, because 

 of the prices of feed, may give the largest money re- 

 turns to the feeder. The use of feeding standards must 

 be accompanied with judgment on the part of the feeder 

 regarding the individuality of the animal, and the char- 

 acter of feeds and their cost, as well as the object of 

 feeding. That is, animals must be fed as individuals, 

 with peculiarities of appetite, digestion, and assimila- 

 tion, not as fixed machines. 



Nutritive Ratio. In a ration for simple mainte- 

 nance, the proportion of the fats and carbohydrates to- 

 gether may be greatly in excess of the digestible 

 protein; while for the production of milk, or of flesh 

 products which are rich in albumen and casein, the 

 direct and only source of these compounds, viz., digest- 

 ible protein, should be proportionately increased. The 

 proportion of the one class of substances to the other 

 is called "nutritive ratio," and is obtained as fol- 

 lows : 



The sum of the digestible carbohydrates and two and 

 one-fourth times the digestible fat is divided by the 

 digestible protein in the ration ; the quotient gives the 

 nutritive ratio. The calculation of the nutritive ratio 

 of clover hay, from the analysis and digestibility given 

 on page 156, will serve as an example of the method : 



Digestible Fat, X 2i = 3.19 



Digestible Carbohydrates = 34.00 



37.19 

 Digestible Protein 6.03 



