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PRINCIPLES OF AGRICULTURAL CHEMISTRY 



3. The age of the animal has no influence, unless the animal is 

 too young for the food given, or too old to masticate it properly 

 on account of defective teeth. 



4. Animals resting or at moderate work have the same diges- 

 tive power. Vigorous work appears to cause a slight decrease. 



5. Variations in light, temperature, and other external con- 

 ditions, if great excitement is not caused thereby, have no effect. 



Composition of Feed. Different quantities of roughage fed 

 alone are digested to the same extent. This is evident from the 

 experiments of Henneberg and Stohmann with oxen, and E. 

 Wolff with horses and sheep. 



Different quantities of roughage and concentrates, mixed in 

 the same proportions, appear to be digested slightly less with a 

 heavy ration than with a moderate ration. 



The addition of fat and oil does not affect the digestibility of 

 the other nutrients, provided not over I pound per 1,000 pounds 

 live weight is fed. 2 The oil must also be emulsified or finely 

 divided, for liquid oil may occasion depression in digestibility, 

 probably because it hinders the wetting of the food, and thereby 

 the entrance of the digestive juices. 



According to many experiments, the addition of digestible 

 carbohydrates or non-protein will cause a depression of digesti- 

 bility if the proportion of protein to carbohydrates is thereby 

 made too wide. The following example is from Kuhn, in which 

 starch was added to a ration of meadow hay fed to oxen. 



1 Landw. Versuchs-stat., 1878, p. 19. 



2 Kellner, Landw. Versuchs-stat., 1900, p. 114 and 199. 



