A STUDY OF THE PROTEINS OF CERTAIN INSECTS 

 WITH REFERENCE TO THEIR VALUE AS FOOD FOR 

 POULTRY 



By J. S. McHargue/ 



Assistant Chemist, Laboratory of Chemical Research, Kentucky Agricultural Experiment 



Station 



In view of the present high cost of living, it is well to discuss and to 

 consider seriously the utilization of every available source of sound animal 

 protein, even though such proteins may have hitherto been looked upon 

 as of not enough economical importance to warrant their utilization. 



The object of this paper is to call attention to the efficiency of animal 

 proteins as compared to vegetable proteins, and also to show by com- 

 parative analyses that two very common insects contain proteins which 

 are very similar in character to those contained in the proteins of the 

 higher animals which furnish a large part of our food supply. 



Within recent years wonderful progress has been made in our knowl- 

 edge of the character and properties of proteins. Formerly it was 

 assumed that all proteins were of equal value in maintaining nitrogen 

 equilibrium, regardless of whether such proteins were of animal or vege- 

 table origin. 



Thomas (2),^ who was a pupil of Rubner, was the first to demonstrate 

 experimentally the fact that animal proteins are much superior to vege- 

 table proteins in maintaining nitrogen equilibrium in the animal body. 



In order to demonstrate this fact, he performed the following classical 

 experiment on his own body. In his diet he took large quantities of 

 starch and sugar, and determined the minimum loss of protein under 

 these conditions. He then took meat protein in an amount equivalent 

 to this minimum quantity destroyed and found that if the food was 

 divided into six portions, taken four hours apart, there was no loss of 

 body protein. His experiments were carried still farther, and he showed 

 the relative biological values of proteins of different origin. The following 

 list shows the minimum amounts of different proteins required to protect 

 body protein from loss : 



Gm. 



Bean protein 54 



Gm. 



Meat protein 30 



Milk protein 31 



Rice protein 34 



Potato protein 38 



Bread protein 76 



Indian com protein 102 



' The writer begs to acknowledge his indebtedness to the late Dr. J. H. Kastle, who was much interested 

 in nutrition problems and had suggested a study of the proteins of the grasshopper. 

 ' Reference is made by number to "Literature cited," p. 637 . 



Journal of Agricultural Research, Vol X, No. 12 



Washington, D. C. Sept. 17, 1917 



jv Key No. Ky. — 4 



(633) 



