Protein Requirements of Chickens at Various 

 Stages of Growth and Development 



A. E. Tepper, R. C. Durgin and T. B. Charles 



T' 



'HE protein requirements of growing chicks have been studied by 

 numerous investigators both from the standpoint of determining the 

 optimum percentage levels as well as the most efficient sources or com- 

 bination of sources. Carver et al^; Morris, Thompson and Heller^i; 

 Norris and Heuser22; St. John et aPi; Swift et aP^ ^nd Tepper, Charles 

 and Reed^^ have all reported rather similarly that during early life the 

 growing chick has a greater demand for protein than during later life. 

 Norris and Heuser22 report that greatest gro\Hh during the first eight 

 weeks was attained when the ration contained approximately 20 per cent 

 protein. Following this initial starting period, however, the protein re- 

 quirement dropped to about a 15 per cent level. Tepper et aP^ have 

 reported that a 20 per cent protein level is most desirable and efficient 

 for battery brooding of chicks up to thirteen w^eeks of age. 



Curtis et aP state, "Feeding experiments with chicks at this experiment 

 station have demonstrated that considerable variation exists in the nu- 

 trition value of animal protein concentrates." They also report previous 

 work by investigators of the same station^s. 26, 27, therein it was found that 

 meat meals and digester tankage were inferior to meat scraps when fed at 

 the same protein levels. As reported by Prange et aW a deficiency of 

 the amino acid tryptophane was noted in the meat meal. Prange et aP^ 

 further state: "Variations exist in the nutritive value of proteins from 

 meat and bone scraps made by different manufacturers. The cause of 

 this variation is not definitely known, but we surmise it may be due to 

 differences in both amounts and kinds of tissues included in the product. 

 The variation exists not only in similar products made by different manu- 

 facturers but it is possible that it may exist in different samples of the 

 same brand." Mitchell, Beadles, and Kruger^' agree with Prange et al2*, 

 that probably the variation in the nutritive value of the various samples 

 is due to various percentage contents of connective tissue. 



Record et aP in comparative feeding trials on chicks of various types 

 of fish meals state that "all the rations which contained fish meal, with 

 the exception of the ration containing flame-dried menhaden, showed a 

 greater efficiency than the meat scraps alone or meat scraps and five per 

 cent milk rations". The investigators refer, however, to the work of 

 Asmundson and Bicly'' wherein no significant difference was observed in 

 the nutritive value of salmon and pilchard meals or dried skimmilk when 

 fed at levels to supply ten per cent of protein. 



Johnson and Brazie^^ in a test of the comparative value of Argentine 

 meat scrap, Vico meat scrap, Alaska herring meal, fish shreds, skimmilk 



