238 Elementary Principles of Agriculture 



is called the "nutritive ratio" and is taken to mean the 

 ratio of the digestible proteids to the digestible car- 

 bohydrates plus 2.25 times the fat. (The fat has two 

 and one-fourth times as much heat energy per pound 

 as the carbohydrates.) Thus, in the preceding example, 

 the nutritive ratio is 1:11.6, which means that the heat- 

 producing nutrients are 11.6 times greater than the 

 tissue-building nutrients. 



EXAMPLE WITH COWPEAS. 



Proteids Carbohydrates Fats 

 Grams Grams Grams 



Nutrients in cowpeas 21.44 62.16 2.38 



Digested and retained 8.68 55.30 2.24 



Undigested waste 12.76 6.86 .14 



Ratio for digestible nutrients is 8.68 :(55.30+2.24X 2.25) = 



8.68: (55.30+5.60) 

 8.68: 60. 90 = nutritive* ratio 1:7.01 



The ratio calculated according to the chemical 

 composition is 1:3.1, which we see would be quite mis- 

 leading, judging by the actual ratio of digestible nutri- 

 ents which is 1:7.01. 



334. Application of Ratios. The ratio of flesh-form- 

 ing nutrients to the heat-producing nutrients should be 

 suited to the condition and requirements of the animal. 

 Animals at heavy work, where the muscle materials 

 are being used up, require relatively more proteids 

 than when merely at rest. Likewise, young and grow- 

 ing animals require plenty of building material, or 

 animals which produce substances like milk, eggs 

 and wool, substances that contain 'large quantities 

 of proteids, should have food rich in proteids. (See 

 table B in Appendix.) 



