May, 1939] Protein Requirements of Chickens 3 



powder and various blends of these protein concentrates in rations for 

 growing chicks report: "Chicks fed Alaska herring meal made the best 

 growth, those fed Argentine meat scrap made the poorest, while those fed 

 the concentrates and blends of concentrates showed a growth about 

 midway between the two." 



Although there appears to be some agreement among investigators as 

 to the desirable percentage of protein needed in rations for the various 

 purposes of starting, growing, fattening and egg production, there seems 

 to be much less agreement as to the best sources of this protein. Ap- 

 parently the general term "protein" is too inclusive for a satisfactory- 

 decision, and the analyst must go further into a study of methods of 

 manufacture, vitamin content, digestibility coefficients, cost, amino acid 

 content, blends of products used in manufacture of protein concentrates 

 as well as other factors. The reader is referred to a recent article by 

 Fairbanks^o \^ which he discusses this "all inclusive" term in a very able 

 manner. 



Object 



The threefold object of the experimental procedure herein reported was 

 to determine (1) optimum levels of protein intake for chickens during 

 their various stages of growth and production, (2) efficient sources of 

 protein and (3) the most efficient combinations of sources for the various 

 growth periods studied. It was also thought desirable to determine the 

 influence of (1), (2), and (3) on growth rate, sexual maturity, feather 

 growth, feed consumption, mortality, egg production and egg weight. 



Experimental 



In Test I. twelve groups of 30* New Hampshire chicks were started 

 April 4, 1935, and raised in growing batteries up to 12 weeks of age. At 

 this time representative groups of ten pullets from each lot were selected 

 and held for placement in individual laying cages to continue growth and 

 production up to 70 weeks of age. The groups were fed various protein- 

 carrying rations as outlined below: 



Table I. Percentage content of protein, calcium, phosphorus and ash in 

 protein concentrates and basal ration 



* In Test II, twelve groups of 60 New Hampshire chicks were started April 7, 

 1937. Representative lots of 20 pullets from each group were selected and held for 

 placement in laying cages. 



