254 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Past work on the composition of agricultural crops has been di- 

 rected chiefly toward what may be termed the quantity viewpoint. 

 This new work will be directed more toward the subject of quality. 

 For instance, it is known that the application of a certain fertilizer, 

 say, sodium nitrate, at a definite time, as one month after sowing, to a 

 crop like corn will increase the yield quantitatively. However, prac- 

 tically nothing is known about quality relations; that is, whether 

 the proteins, vitamines, or mineral components of the corn fertilized 

 in such a Avay are better suited to animal and human nutrition than 

 those of unfertilized corn. Varietal differences will be studied from 

 a chemical viewpoint. For instance, it will be determined if there 

 are any fundamental chemical differences in the composition of flint 

 or hard corn and the dent corn largely produced in the United 

 States, in an endeavor to determine the reason for the preference of 

 the European countries for Argentine or flint corn to corn produced 

 in the United States. 



PROTEIN INVESTIGATIONS. 



One of the most important researches now under way is that upon 

 vegetable proteins. Inasmuch as nitrogen is an essential part of 

 animal tissues and the animal can obtain this necessary nitrogen 

 only in the form of protein in its feed, it is obvious that this class 

 of feeds is of prime importance. This research involves the very 

 existence of all animals and is inseparabl}^ connected with the field 

 of nutrition. 



Until quite recently one kind of protein in a diet was considered 

 as good as-another. To-day we laiow that one protein differs from 

 another protein in certain fundamental constituents called amino 

 acids, of which all proteins are composed. Some of the amino acids 

 are absolutely essential for nutrition, for without them animals will 

 not grow, but will soon fail and die. The protein of corn is deficient 

 in two essential amino acids, tryptophane and lysine. A young 

 animal on a diet having its sole source of protein derived from 

 whole com will not grow and develop properly. However, if the 

 protein of corn is supplemented by the addition in the right pro- 

 portion of certain other proteins, the protein of the mixture will 

 then be adequate for normal growth. From this it follows that an 

 exact knowledge of the chemical composition of the different pro- 

 teins in feeds is necessary. It is essential not only to know whether 

 in themselves they are adequate for the needs of the animal but also 

 to know when they are deficient, what other proteins, and in what 

 proportion, must be added to supplement the deficiency. The per- 

 centage of nitrogen alone can not therefore any longer be regarded 

 as an index of the protein value of a feeding stuff. 



The amino acids of the proteins of several agricultural products 

 have been separated and studied, with the result that it is now pos- 

 sible to supplement such basic feeding stuffs as corn with small quan- 

 tities of other feeds, such as peanut meal, soy-bean meal, and coconut 

 press cake, which contain the very amino acids corn lacks, thus mak- 

 ing a feed that will supply all the amino acids necessary for growth. 

 The practical results of this should be a greater and more profitable 

 utilization of our largest cereal crop, corn. 



