XIII. REQUIREMENTS 507 



XIII. Requirements 



THOMAS H. JUKES and WILLIAM L. WILLIAMS 



Tho vitamin B12 reciiiirement of most animals which have been studied 

 api)ears to be in the neighborhood of 10 7 per kilogram of diet. The reciuire- 

 ment is increased by raising the protein content of the diet, by hyperthy- 

 roidism including the feeding of thyroxine, and by reproductive activities 

 in tlie female. Vitamin B12 is unusual in two respects. First, the apparent 

 requirement may be markedly influenced in human beings by a degenerative 

 process in the gastric mucosa which diminishes the uptake of the vitamin 

 from the gut, thus necessitating either the oral administration of massive 

 doses, or the injection of the vitamin, or the feeding of preparations of the 

 "intrinsic factor." Second, a dietary deficiency of cobalt in ruminating ani- 

 mals apparently leads to a diminution of the production of vitamin Bi2 by 

 microorganisms in the paunch, thus resulting in vitamin B12 deficiency in 

 the animal. 



The information regarding vitamin B12 in the nutrition of certain animals 

 is summarized in the following pages. 



A. OF CHICKS 



THOMAS H. JUKES and WILLIAM L. WILLIAMS 



The nutritional requirements of chicks for rapid growth and good hatch- 

 ability are marked and exacting. The history of the successful development 

 of the poultry industry is interwoven with the discovery of certain vitamins 

 and their use in feeds. As knowledge of the vitamins expanded, it appeared 

 that certain animal protein feedstuffs contained a factor which was needed 

 for hatchability and growth and that this factor differed from riboflavin.^-^ 

 Research in this field was stimulated by the occurrence of a shortage of 

 animal proteins, especially fish meal and milk, which was occasioned by 

 wartime conditions. Simultaneously the rate of commercial production of 

 chickens for meat increased and it became necessary to use larger propor- 

 tions of two of the most readily available feedstuffs, corn and soybeans. 

 These two feedstuffs are deficient in vitamin B12, and many investigations 

 were involved with circumstances arising from this fact. 



Investigations by Hammond^ showed that cow manure or dried rumen 



' J. B. Christiansen, H. J. Deobald, J. G. Halpin, and E. B. Hart, Poultry Set. 19, 

 18 (1940). 



2 J. S. Carver and R. J. Evans, U. S. Egg Poultry Mag. 49, 468 (1943). 



3 T. C. Byerly, H. W. Titus, N. R. Ellis, and R. B. Xestler, Poultry Sci. 16, 322 

 (1937). 



* R. B. Nestler, T. C. Byerly, X. R. Ellis, and H. W. Titus, Poultry Sci. 15, 67 (1936). 

 ' W. W. Cravens, W. H. McGibbon, and J. G. Halpin, Poultry Sci. 24, 305 (1945). 

 6 J. C. Hammond, Poultry Sci. 21, 554 (1942); 23, 358, 471 (1944). 



