amounts. These are the inusde-inakers (proteids, protein, albumin- 

 oids or nitrogenous substances) and i\\Q fat-7)ia1cers (fats and carbo- 

 hydrates). Tlie chief ottice of the muscle-makers is to build up all 

 parts of the body which have work to do, including, with the other 

 vital organs, the milk machinery of a cow's udder. They also enter 

 largely into the composition of nearly all animal products, as hair, 

 wool, eiTffs, lean meat and milk. The chief function of the fat- 

 makers, on the other hand, is to supply the fuel from which the 

 animal heat is maintained. They also supply, at least in part, tlie 

 energy which enables the muscles to work and they enter largely 

 into the composition of various products, particularly eggs and 

 milk. Any surplus of these substances which the food contains 

 may be and usually is stored up in the tissues of the body as fat. 

 These statements show what usually takes place, but since the 

 muscle-makers may perform any of the functions of the fat-makers, 

 it is more exact not to speak of these substances according to their 

 functions but according to their composition and to refer to them as 

 protein, and fats or carbohydrates, instead of muscle-makers and 

 fat-makers. 



We might illustrate roughly the main point to this problem of 

 stock feeding by saying that a cow is something like a grist mill, 

 and that her stomach is the hopper. A mill will grind out only the 

 grist of what is put into the hopper; just so a cow in a large meas- 

 ure will turn out fat or milk according to the food Avhicli we put 

 into her stomach. Are you keeping a cow for milk ? Then feed 

 largely milk-makers. Are you raising a steer for beef? Then feed 

 more fat-makers. Does not this seem reasonable ? 



Now let us see which among the different kinds of hays, grains 



and fodders that we commonlv feed to our farm animals contain 



carbohydrates or protein in large amounts. The chemist takes all 



of them into his laboratory and treats them with chemicals for many 



hours. Finally he tells us that every one of them contains both 



protein and carbohydrates, but itiost of them are richer in one or 



the other. So we must not think to find our muscle-makers and 



fat-makers put up in separate packages, ready to be mixed as needed. 



They are comhined in different proportions in all kinds of feeding- 



550 



