SECTION VI. 



PROTEIN IN PLANTS AND ANIMALS. 



Protein (nitrogenous compounds), includes all compounds of 

 the plant and animal body containing nitrogen. Protein is made 

 up of carbon, oxygen, hydrogen and nitrogen ; generally sulphur ; 

 sometimes phosphorus; and in a few cases iron. About i6 per 

 cent, of the protein is nitrogen. Protein is perhaps the most 

 important constituent to consider in the feeding of animals. 



The compounds of protein are classified by the Association of 

 American Agricultural Colleges and Experiment Stations as 

 follows : 



Protein, 

 Total nitrogen 

 compounds 



Protein in the Plant. — Protein is found in the plant as al- 

 buminoids and amides. The albuminoids are represented as leg- 

 umin, the nitrogenous compound of legumes (peas, bean, alfalfa, 

 clover, etc.), as gluten of the wheat grain, and as vegetable 

 albumen resembling white of egg, which is found in the juices 

 of plants. Crude gluten may be obtained by washing dough of 

 wheat flour to a sticky mass. Most of the protein of feed stuffs 

 is present as albuminoids. Amides are soluble in water and are 

 considered more abundant in young plants and growing parts of 

 plants. It is believed that the function of amides is to transfer 

 nitrogen from one part of the plant to another. The nitrogen of 

 roots, tubers, and cane molasses is more largely made up of 

 amides than in other feeds. The grains and seeds contain less 

 of such nitrogen compounds than other feeding stuffs. The 

 flesh forming function of amides is doubtful and so the protein 

 obtained from roots, tubers and cane molasses is not considered 

 as valuable as that from grains and seeds. 



