EXPERIMENT STATION. 449 



Nitrogenous substances, or protein matter, refer to several 

 groups of nitrogen-containing compounds, of plants in par- 

 ticular, as albumin, fibrin, legumin, casein, etc., which are 

 essential for the formation of blood and tissues. Those con- 

 tained in animal matter, as meat refuse, are frequently con- 

 sidered of a higher value than those in many plants. 



Non-nitrogenous substances include, in particular, starch, 

 sugars, organic acids, gums, fats and the digestible portion 

 of the cellular matter of the fodder. These substances are 

 readily transformed within the digestive organs into soluble 

 compounds of a similar chemical character, and are thus 

 assumed to serve an identical physiological purpose. As 

 mor6 recent investigations have shown a superior physiologi- 

 cal value of fat, — one of the non-nitrogenous constitutents, — 

 two and one-half times as much as starch, sugar, and other 

 representatives of that group, its amount is separately re- 

 corded. The same course, for similar reasons, has of late 

 been adopted with reference to certain forms of nitrogenous 

 organic constituents of fodder articles. 



Fatty substances include all the various natural fats of the 

 plant. Most plants contain more than was assumed at an 

 earlier stage of inquiry. As the fat is separated by means 

 of ether, the statements in the analyses do not exactly ex- 

 press the amount of fatty matter alone, but include more or 

 less resinous substances, wax, etc., which are largely soluble 

 in ether, and of a similar highly carbonaceous character. The 

 fat of the fodder seems to serve, in case of judicious fodder 

 rations, mainly to increase the stock of fat in the animal 

 which consumes the fodder. 



Wherever the article has been tested bv actual feedinsr ex- 

 periment under skilful observation, the amount of each essen- 

 tial group of food constituents which has been shown to be 

 digestible is reported in connection with the chemical analy- 

 sis, under the heading Digestible Portion, per hundred weight 

 or per ton. The higher or lower degree of digestibility of a 

 fodder article exerts a decided influence on its nutritive value. 

 Different stages of growth affect the rates of digestibility of 

 the various plant constituents. The same feature is noticed 

 in regard to different parts of plants, as well as in case of 

 different kinds of animals. 



