COMPOSITION OF FOODS 131 



Composition of Poods.— The average percentage com- 

 position of the foods commonly given to farm animals 

 is shown in the preceding table. The figures given 

 are in every case the mean of a large number of 

 analyses. 



The total " nitrogenous substance *' in a food is 

 obtained by multiplying the percentage of nitrogen by 

 6*25/ it thus represents approximately the amount of 

 albuminoids present, if the whole of the nitrogen exists 

 in this form. It is now, however, well known that a 

 part of the nitrogen of vegetable foods exists, not as 

 albuminoids, but as amides (asparagine, glutamine, 

 leucine, tyrosine, &c.), and in some cases as nitrates. 

 The following table shows the average proportion of 

 the nitrogen which exists in the form of albuminoids 

 in various foods, according to the analyses at present 

 published ; numbers marked with an asterisk are the 

 mean of few analyses. 



It appears from these numbers that the greater part 

 of the nitrogen in ripe seeds exists as albuminoids ; 

 in rape cake, in leguminous seeds, and in rye and 

 wheat, the proportion of albuminoid nitrogen is rather 

 lower than in the other cases. In germinated grain, 

 as malt, a considerable part of the albuminoids is 

 replaced by amides. The few analyses of ripe straw 

 show that the nitrogen present is chiefly albuminoid. 



' The use of this factor assumes that the nitrogenous matter 

 contains on an average 16 per cent, of nitrogen. The amount of 

 nitrogen in various albuminoids varies from about 15 — 10 per cent. 

 Some of the amides present in foods contain more nitrogen and some 

 less nitrogen than albuminoids. Our knowledge of the composition of 

 foods is only in a few cases sufficiently exact to enable us to state the 

 exact weight of albuminoids and amides present. 



