FOOD NUTRIENTS 45 



Most Feeding Stuffs are Unbalanced. If every 

 food were wholly digestible and the digestible pro- 

 tein, digestible carbohydrates and digestible fats 

 were united in every feeding stuff in just the right 

 proportion to meet the needs of the particular ani- 

 mal, life feeding of farm animals would be a simple 

 problem. But plants vary in composition ; their 

 food constituents are neither all nor yet equally 

 digestible; some are much concentrated in form, 

 while others place their food nutrients in large bulk. 

 Because of these differences in the nature of feed- 

 ing stuffs it is necessary to resort to wide variety 

 and to blend or mix the provender that the varying 

 needs of the various classes under continuous 

 change of method of feeding or of age or of pur- 

 pose may be met. This gives rise to the compound- 

 ing of rations for each special class of live stock. 



But few single feeding stuffs furnish the required 

 quantities of protein, carbohydrates and fat; the 

 most economical and best results are secured when 

 two or more are combined. By such a combination, 

 if one feed is lacking in protein, for instance, this 

 deficiency may be met in the ration through the 

 selection of another substance possessing the pro- 

 tein element in unusual abundance. In this man- 

 ner the shortage of the one is balanced by the 

 abundance of the other. 



Digestibility Denned. Every feeding stuff con- 

 tains protein, carbohydrates, fat, ash and water. Of 

 each of these there is a distinct proportion absorbed, 

 and the remainder is rejected and excreted in the 

 feces. The proportion which represents the quan- 



