Protein 53 



It should be stated, by way of preliminary explana- 

 tion, that, in the past, the proportion of protein (total 

 nitrogen compounds) in a feeding stuff has been ascer- 

 tained by determining the total amount of nitrogen 

 and then multiplying its percentage number by the 

 factor 6.25. This method is based on the assumption 

 that the average percentage of nitrogen in protein com- 

 pounds is sixteen, which is not true to so close a de- 

 gree of approximation as was formerly believed to be 

 the case. It may happen in some instances that a 

 determination made in this way is sufficiently accurate, 

 while in other cases the margin of error is large. Re- 

 cent investigations with perfected methods show per- 

 centages of nitrogen in the numerous single proteid 

 substances found in the grains ranging from 15.25 to 

 18.78. These are largest in certain oil seeds and lu- 

 pines and smallest in some of the winter grains. Ritt- 

 hausen, a prominent German authority, concedes that 

 the factor 6.25 should be discarded, and suggests the 

 use of 5.7 for the majority of cereal grains and legu- 

 minous seeds, 5.5 for the oil and lupine seeds, and 6.00 

 for barley, maize, buckwheat, soja bean, and white 

 bean (Phaseolus), rape, and other brassicas. Nothing 

 short of inability to secure greater accuracy justifies 

 the longer continuance of a method of calculation 

 which is apparently so greatly erroneous. 



As previously stated, protein is the accepted name 

 for a class of compounds. Just how there came about 

 such a grouping of a large number of substances under 

 a single head it is not necessary to consider in this con- 

 nection, but it should be made clear that the individual 



