406 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



effect on digestibility, unless fed in connection with concentrates 

 rich in protein. Concentrates of intermediate composition exert 

 an appreciable effect upon digestion only when the ration con- 

 tains more than 8 parts non-protein to I part protein. In gen- 

 eral, it may be stated, that the digestion of a food is most com- 

 plete when, for 7 to 8 parts digestible nitrogen-free nutriment 

 (including fat X 2 - 2 5)> n ot less than I part digestible crude pro- 

 tein is present. With pigs, which have a high digestive power for 

 carbohydrates, the ratio may be as wide as i : 12. 



Free acid, in moderate limits, has no influence upon digestibility. 

 Experiments were made with sulphuric acid and lactic acid 

 added to the ration of sheep and oxen, as much as 2.67 per cent, 

 lactic acid being fed. Free acids are found in silage. Horses 

 and young animals are often very sensitive to acid. The effect 

 on the teeth must also be considered. 



Carbonate of lime, even in high amounts, had no effect upon 

 digestibility by sheep. Since the acid gastric juice could not have 

 acted, being neutralized by the carbonate of lime, the work of 

 digestion must have been performed by the alkaline pancreatic 

 juice. 



Character of Feed. Dry fodder has the same digestibility as 

 green fodder, when there is no loss in drying, but usually fer- 

 mentation takes place, or leaves, etc., are broken off, leaving 

 material of less digestible character. Young plants are, in gen- 

 eral, more digestible than older ones, and also have a higher pro- 

 ductive value. Corn, however, contains more digestible matter 

 when fully ripe than if cut before the ears are grown. This is 

 due to the production of a large quantity of highly digestible 

 grain. 



Stage of Growth. The digestibility decreases with the stage of 

 growth of the plant, more rapidly as the plant approaches 

 maturity. An exception is Indian corn, which forms a large 

 amount of easily digested grain as it approaches maturity. 



B. E. Wolff obtained the following results with clover cut at 

 different stages of growth: 



