PRINCIPLES OF STOCK FEEDING 191 



together. The fat content of a feeding-stuff is multi- 

 plied by 21/4 and the product is added to the amount of 

 carbohydrates present. 



No other class of chemical compounds comprises so 

 large a part of stock foods as the carbohydrates. In 

 some cases, as in certain varieties of hay and grain, 

 they comprise 80 per cent of the dry matter. While 

 abundant in most food-stuffs, they are nevertheless a 

 valuable constituent, as being the chief source of energy 

 and fat. 



Fat, or Ether-Extract. — The percentages indicated in 

 the column headed "Ether Extract" in the table follow- 

 ing include several compounds, mainly, however, fats 

 that are soluble in ether. The value of the ether-extract 

 in a given food-stuff depends largely upon its nature. 



DIGESTION AND GROWTH 



Since only a part is digested, not all the nutrients 

 in food-stuffs nourish the animal body. We speak of a 

 given food-stuff as containing a certain number of pounds 

 of protein per hundredweight. While this knowledge 

 may in certain instances be useful to the feeder, the 

 important thing to know is, how much available pro- 

 tein is present and the character of the feed that con- 

 tains it. 



Conditions Affecting Digestion. — In the processes of 

 digestion, such portions of the food nutrients as are 

 digestible are converted into a form which may be readily 

 taken up by the absorbent vessels of the stomach and 

 intestines. The undigested portions of food-stuffs are 

 believed, in certain instances, to serve the purpose of 

 distending the stomach and intestines. In general, a 

 much higher percentage of the food nutrients in concen- 

 trates is digested than in roughages containing a large 

 amount of crude fiber. Other conditions, also, affect 

 the relative digestibility of nutrients in food-stuffs: 

 (1) Certain species of animals, such as cattle, sheep, and 

 other ruminants, digest a higher percentage of 3rude 



