DEFINITIONS AND TECHNICAL CONSIDERATIONS. 357 



J)ry matter. "When a substance has been satisfactorily desiccated by 

 heat, there remains what is known as dry matter. 



Energy. The capacity of doing work; the power of an organism. 



Ether extract. In most text books, the ether extract is called " fat." 

 Its estimation is very simple, consisting in drying the fodder and adding 

 ether which will dissolve the fat and like substances. Its percentage varies 

 very considerably in plants in general. 



Fatty substances. The fatty substances are those which may be dis- 

 solved from feeding stuffs with ether, and necessarily include coloring matter, 

 wax, etc. The fat is assimilated and burned to form heat and consequently 

 energy, or it is stored up and deposited as fat when taken in excess. 



During the fat combustion the heat of the animal's body is supplied. An 

 exertion of any kind is followed by fat burning, just as fuel is burned under a 

 boiler. Fat necessarily plays a very important role during fattening of live 

 stock as it accumulates in different parts of the body, gives it weight and in- 

 creases its value from a butcher's standpoint. It is to be noted that only a 

 small percentage of the fat enters the blood vessels forming part of the intes- 

 tines, the larger portion passing through the lymphatics. While it is gener- 

 ally admitted that fats undergo very little change when forming part of the 

 circulation, the fact nevertheless remains that the role they subsequently play 

 in the tissues varies with the animal fed. 



Experiments have been made 10 uetermine the heat units of feeds, and those 

 relating to fat are of an exceptional interest. For this purpose a calorimeter 

 is used, the substance to be tested is burned therein, and the heat given off is 

 absorbed by water. Prof. Runner's experiments show that 235 parts of lean 

 meat, when burned in the apparatus, give off' the same heat as 100 parts of fat. 

 A gram of fat is shown to yield over twice the calories yielded by a gram of 

 carbohydrates; for feeding purposes it is found that they are equally valuable 

 as influencing protein consumption, hence they may be substituted one for the 

 other. It must be noted that fodders containing considerable fat are difficult 

 to digest and are expensive and therefore should be used with certain discre- 

 tion. AY hen considering ruminating animals in general, one had better rely 

 upon carbohydrates which most feeds contain in reasonable proportions, and, 

 which within themselves are furnished at a comparatively low cost; further- 

 more, as they decrease the daily protein consumption, they keep the animal 

 fed in a good healthy condition with a very restricted absorption of nitrog- 

 enous substances. Respecting the influence of fat upon a decreased pro- 

 tein consumption, Yoit's experiments demonstrate beyond cavil, that the fat 

 when fed alone, rather tends to increase than decrease the protein assimilated. 

 This fat diet appears to have very little influence upon the fat already stored 

 up in the body, and as the fattening of live stock continues, the process of fat 

 deposits is more and' more difficult from the feeder's standpoint. Experiments 

 have been made in feeding fat and protein alone. When the quantity of pro- 

 tein fed was the same from day to day and the amount of fat increased, the fat 



