26 FEEDING VALUE OF CEREALS. 



PRODUCTIVE VALUE AND NUTRITIVE. RATIO AS A BASIS FOR EXACT VALUATION. 



From a study of the data presented in these or similar tables of 

 analysis of feeding stuffs, it is seen that by considering simply differ- 

 ences in the amounts of the four nutritive constituents a very indefi- 

 nite conclusion is often reached. If two distinct!}' different cereals 

 are considered, such as oats and corn, the differences in the amounts 

 of the nutritive constituents are considerable, as would be expected. 

 When, however, we have to deal with cereals that are very similar, 

 such as rye and wheat, or with simply different samples or varieties 

 of the same cereal, the differences in the amounts of the nutritive 

 constituents are so small and so nearly counterbalance each other 

 that it is impossible to form any opinion as to their relative value 

 based on these factors alone. It is, therefore, necessary to secure 

 some factor that either sums up or magnifies the slight differences in 

 composition if a true valuation of similar feeding stuffs is to be made. 

 Even with such a factor it is natural that differences should not be 

 great between different samples or different varieties of the same 

 cereal. The most distinct!}' different foreign and domestic oat, for 

 example, can not show wider differences in composition than are 

 possible between plants belonging to the same species. 



Various efforts have been made to obtain such a factor, and it has 

 seemed to the writer that the best comparison and relative valuation 

 of similar or slightly different samples of feeding materials is secured 

 by a consideration of the production wtlv.f. and especially when this 

 is considered in connection with the nutritive ratio. The production 

 value gives, in the most accurate terms known, the amount of energy 

 (expressed either in calories, weight of flesh gained, or in any other 

 unit), which a definite amount of a certain food will produce when 

 fed as a production ration in addition to a basal maintenance ration. 

 The nutritive ratio gives the relation between the protein and other 

 nutrient constituents of a food, i. e., between the constituents essen- 

 tial in producing muscular energy and those essential in producing 

 fat and heat. As the uses of various foods are different, one class for 

 producing muscular energy or work and the other class for increasing 

 flesh or maintaining animal heat, so the value of a food will depend 

 upon the use for wilich it is intended, and it is not possible to use any 

 factor for the valuation of foods without considering this point. 



Cereal grains, as a class, are naturally much alike in their general 

 composition, but may be divided into two subclasses or groups, the 

 one typified by oats or wheat, high in protein, relatively low in 

 carbohydrate, with a narrow nutritive ratio, and the other, typified 

 by maize, being the opposite of the first, low (relatively) in protein, 

 rich in carbohydrate, and with a broad nutritive ratio. 



With these two typical grains as examples we may judge of the 

 tendency of a variety or sample, under certain observed conditions 



