CONTROL BULLETIN No. 113 



RIBOFLAVIN CONTENT OF VARIOUS PRODUCTS 

 J. W. Kuzmeski 



Riboflavin, a factor of vitamin G, is essential to growth. It is of especial im- 

 portance in the diet of poultry. Until recently, dependence has been placed very 

 largely upon milk products in securing adequate amounts of this important 

 vitamin. With the growing scarcity of dried milk products, substitutes have 

 been sought. Those which have received the greatest consideration are dried 

 distillers solubles and concentrates made from them and other distillery residues. 



In addition to tests with small animals there are two accepted methods for the 

 determination of riboflavin: the microbiological and the fluorometric. For the 

 results reported, the latter was adopted, using the Coleman spectrophotometer 

 with attachments for fluorescence measurements. Where check tests were 

 attempted with other laboratories, a considerable but not serious variation was 

 found in some instances, possibly due to the fact that the methods are of com- 

 paratively recent origin and may contain imperfections which will be eliminated 

 eventually. In the meantime more or less variation may be reasonably expected 

 in the results reported by different laboratories. In general the apparent ribo- 

 flavin content found by the fluorometric method is somewhat lower than that 

 obtained microbiologically. 



A comparatively low riboflavin content of a feed does not necessarily condemn 

 it. In some products this is merely incidental and the product is primarily used 

 for some other element or elements it may contain. 



In order to present data not generally available, riboflavin tests are reported 

 on a variety of products which are or might conceivably be used as sources of the 

 vitamin. Where two or more samples were tested, the results are averaged un- 

 less the individual results were so utterly at variance as to make an average mean- 

 ingless. 



It is the intention to make a more extended survey particularly of those com- 

 mercial mixtures for which a high riboflavin content is claimed. 



