Principles and Practice of Stock Feeding 7 



crude fiber and kindred substances. Cattle and sheep digest it fairly well, 

 other animals but slightly. 



Nitrogen-free extract is a term applied to a somewhat miscellaneous 

 group of nutrients, none of which contain nitrogen, and>ll of which are 

 dissolved by dilute solvents. Its principal constituents are starch, sugars, 

 gums and similar substances. Starch is usually more abundant than the 

 others and the group on this account is sometimes called "starchy matter." 

 The nutritive functions of crude fiber and of the nitrogen-free extract are 

 similar, hence the collective term in common usage, carbohydrates, is in 

 many ways preferable. 



Since enough ash is present in almost all rations to meet bodily needs, 

 and since water is otherwise supplied, in compounding rations the feeder 

 has to do only with protein, fat and carbohydrates. 



SUNDRY DEFINITIONS 



Certain terms in common use in food analysis or in the discussion of 

 nutrition are defined at the outset that their meaning may be the more 

 clearly apprehended. 



Dry matter, organic matter, digestible dry matter are collective terms. 

 Neither represents any single group of nutrients. The first designates the 

 material — whatever its nature — left when all the water it contains is vapor- 

 ized. For instance silage containing 75 per cent of water carries 25 per 

 cent of dry matter. Organic matter is dry matter less its ash, or, in other 

 words, it is the portion which disappears in burning. In the case just cited 

 nine-tenths or thereabouts of the 25 per cent dry matter would burn off and 

 would be the organic matter. Digestible dry matter is the portion which 

 is capable of solution by the sundry digestive juices and is available as food. 

 It is the true food, the remainder being useless except as it enriches the 

 manure. 



Nutrient and nutritive ratio are terms in frequent use. A nutrient is a 

 digestible ingredient of food, one capable of performing one or more of the 

 food functions. Ash, protein, fat and carbohydrates are nutrients. 



The term nutritive ratio is less readily defined. The primary function 

 of protein is quite different from that of the other nutrients (pages 8-9). 

 On this account the relation of the amounts of protein and of carbohydrates 

 fed to the object in view, as well as to economy in feeding, is of import- 

 ance. The nutritive ratio shows this in figures. It is the mathematical 

 expression of the relation of the amounts of digestible protein and of the 

 other nutrients to each other in a given ration. It is a ratio, a proportion, 

 1:6 or 1:8, the two terms of which are (a) digestible protein and (b) digesti- 

 ble carbohydrates and fat. If there be 2 pounds of a and 12 pounds of b 

 the nutritive ratio will be determined by the common rules of proportion, 

 2: 12: : 1: 6, there being times as much digestible carbohydrates and fat as 



