XII. HECJUIREMENTS AND FA( T()I{S INFLUENCING THEM 



297 



(loxiiic daily ^cow iioi'inally and do not cxliil)!! any dclicicncy symp- 

 toins.'-''' -' 111 all probability, the daily rcuiuiicincnl is less than 1 ni^-. 



7. Chicks 



It ha.s l)oen fairly well established that chicks reciuire 200 to 300 7 of vi- 

 lainin Be per 100 g. of ration for normal growth, egg production, and hatch- 

 ability.-""" When linseed oil meal is fed to chicks at a 30 % level, the vitamin 

 Be recjuirement is increased.-'' Treatment of the linseed oil meal with water 

 removes the factor which is responsible for the increased re(iuirement. 



The Red Rock breed has a higher requirement for vitamin Be.^^ When 

 Ivcd Hock cross chicks were fed diets containing 500 7 of xitamin Be per 



10.0 



0.01 



1 10 



Body weight, kg. 

 Fig. 4. Relationship of size of a species to its pyridoxine requirement. 



100 g. of ration, vitamin Be deficiency symptoms appeared. These symptoms 

 disappeared when the pyridoxine content of the diet was increased. This 

 variation in requirement may be due to genetic factors. 



There is no difference in the chick's dietary requirement for vitamin Be 

 in cool temperatures and in tropical heat.^" 



-' K. B. McCall, H. A. Waisman, C. A. Elvehjem, and E. S. Jones, /. Nutrition 31, 



685 (1946). 

 2' J. F. Rinehart and L. D. Greenberg, Am. J. Pathol. 25, 481 (1949). 

 " G. M. Briggs, Jr., R. C. Mills, D. M. Hegsted, C. A. Elvehjem, and E. U. Hart, 



Poultry Set. 21, 379 (1942). 

 " W. W. Cravens, E. E. Sehesta, J. G. Ilalpin, and E. B. Hart, Poultry Sci. 25, SO 



(1946). 

 " F. H. Kratzer, F. H. Bird, V. S. Asmundson, and S. Lepkovsky, Poultry Sci. 26, 



453 (1947). 

 " F. H. Kratzer and D. E. Williams, J. Xutrilion 36, 297 (1948). 

 2" H. L. Lucas, G. F. Heuser, and L. C. Norris, Poultry Sci. 25, 87 (1946). 

 « C. A. :Mills, E. Cottingham, and E. Taylor, Am. J. Phyi^iol. 149, 376 (1947). 



