TJSES OF PEED BY ANIMALS— FEEDING STANDARDS 47 



The formation of body fat from protein in the feed may be 

 considered established by experiments with carnivorous animals, 

 especially dogs. It is known that the protein molecule can be 

 split up into a non-nitrogenous portion (dextrose) and urea; it is 

 readily seen, therefore, that the feeding of protein may result in 

 the formation of glycogen and subsequent deposition of fat in the 

 body. That 'the same holds good in the case of herbivorous animals 

 is indicated by the fact that mature steers and sheep will grow very 

 fat on good alfalfa pasture, or when fed rations very high in pro- 

 tein, like alfalfa and cottonseed meal. 



Protein substances may also furnish material for the production 

 of heat and energy when supplied in relatively large amounts, but in 

 ordinary farm practice this is not likely to happen, since the rations 

 fed are usually high in starchy components, which supply by far 

 the larger proportion needed for heat production. In addition to 

 serving the purposes stated, as a source of body protein and of fat 

 and heat production, protein stimulates the activities of the body 

 cells. A liberal supply of protein is, therefore, of special im- 

 portance in cases where the metabolic processes in the body are very 

 active, like rapidly growing animals, heavy producing milch 

 cows, etc. 



Non-protein is mainly present in succulent feed stuffs in the 

 form of amides or nitrates, the latter in case of root crops. These 

 substances are wholly digestible, being soluble in water and capable 

 of diffusing through the animal cell wall. In the case of ruminants, 

 the addition of non-protein (asparagin) to a ration low in protein 

 but high in carbohydrates, will effect a saving of the former ; these 

 substances are generally considered of value for saving protein 

 from decomposition, leaving more of these available for production 

 of body protein ; but it is not believed that they can cause' an actual 

 increase of protein tissues in the .body. It is a significant fact, 

 however, that many feeds relatively high in non-protein, like pas- 

 ture grass, silage crops, malt sprouts, root crops, are among our 

 most valuable feeds for farm animals, especially, ruminants, thus 

 suggesting that non-protein substances possess a 'high value in 

 stock feeding (p. 11). 



Functions of Carbohydrates. — The functions of 'the nitrogen- 

 free organic substances (carbohydrates and fait) in the nutrition of 

 farm animals, are to supply material for the formation of body fat 

 and for production of heat or work. The question whether carbo- 

 hydrates may be used for the formation of fat in the animal body 

 was long a disputed one, and has been the subject of numerous 

 investigations. It may now be considered settled that these sub- 

 stances as a rule form the most important source of hody fat in the 



