1887.] PUBLIC DOCUMENT — No. 33. 35 



Nitrogenous substances, or protein matter, refer to several 

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

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

 essential for the formation of blood and tissues. Those 

 contained in animal matter, as meat refuse, are frequently 

 considered 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 solu- 

 ble compounds of a similar chemical character, and are thus 

 assumed to serve an identical physiological purpose. As 

 more recent investigations have shown a superior physio- 

 logical value of fat, — one of the non-nitrogenous constitu- 

 ents, — two and one-half times as much as starch, sugar, and 

 other representatives of that group, its amount is separately 

 recorded. 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 .by actual feeding 

 experiment under skilful observation, the amount of each 

 essential group of food constituents which has been shown 

 to bo digestible is reported in connection with the chemi- 

 cal analysis, under the heading Digestible Portion, per hun- 

 dred 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. 



