THE NUTRIENTS AND NUTRITION 



307 



geese in the form of fat, and that this fat must have been 

 built up out of the carbohydrate (starch). 



The great difference between the foregoing and protein is 

 the presence of nitrogen in the latter. While fat and carbo- 

 hydrate are mutually interchangeable in feeding practice 

 to a considerable extent, neither of them can be fed in the 

 place of protein. Protein, on the other hand, may to a limited 

 extent replace either or both of the other two. This is be- 

 cause of the fact that it contains all the elements to be found 

 in them (carbon, iiydrogen, and oxygen), and by wasting the 

 nitrogen may lie made by the body into energy, or fat. 



Fio 1 IIS 



Liihorator^' (l('\'oLc<l (o llic s1uil\- oj' imhitinu of chickens a( Kansas 

 State Afjrirultiiral Cullej;e. 



This was demonstrated by Wolfl'berg and confirmed by Kulz 

 (as quoted by Lusk'), who showed in feeding fowls chopped 

 meat that part of the carbon of the protein was retained in 

 the body as glycogen (a carbohydrate of the liver). While 

 this is of interest it is not of great practical value, owing to 

 the fact that protein is the most expensive of the five food 

 nutrient groups and the tendency with most poultry feeders 

 is to slight the protein portion of the ration. 



Further Functions of the Nutrients. — Besides furnishing 

 material out of which the parts of the body and egg of the 



Science of Nutrition. 



