84 AGRICULTURAL EXPERIMENT STATION. 



The ash<, or mineral part of an^- food stuff, is that which is left 

 after the combustible portion is burned away, and includes quite a 

 number of compounds. The amount of ash in plants is influenced 

 in a marked manner by their age, and condUions of growth, such as 

 locality, soil, kind of manuring. The mineral compounds of cattle 

 foods fill an important place in furnishing entirely the material for 

 building up the bony framework of the animal. 



Protein is a collective term that includes quite a variety of com- 

 pounds, which are distinguished from the members of the other 

 important classes of substances in feeding stuffs by the fact that 

 they contain nitrogen. Protein includes two general classes of 

 compounds, viz., albuminoids and amides. 



Such compounds as egg albumen, the muscular tissue of animals 

 and the caseine of milk are albuminoids^ and to these animal sub- 

 stances the albuminoids of plants bear a close resemblance both in 

 chemical properties and in food value. The protein of feeding 

 stuffs cannot be directly determined with accuracy. The estimation 

 is an indirect one, and is based upon the fact that all albuminoids 

 contain approximately 16 per cent of nitrogen. If, therefore, the 

 percentage of nitrogen in any feeding stuff be multiplied by 6.25, 

 the percentage of albuminoids is obtained with suflicient accuracy 

 for all practical purposes. The important and peculiar office which 

 albuminoids fill in serving the uses of the animal kingdom is that 

 they constitute the only source of material for the formation of 

 muscular tissue, hair, horn, the caseine of milk, and all other 

 organic nitrogen compounds of the animal body. 



Plants contain other nitrogenous compounds called amides that 

 occur most abundantly in fodder and root crops, the amount 

 varying at different periods of growth, while in the grains the 

 nitrogen exists almost wholly in the form of albuminoids. Fodder 

 tables generally give as the percentage of protein the product of the 

 total percentage of nitrogen by 6.25. 



A given amount of protein, as stated for hay in tables of fodder 

 analyses, is not quite the same thing, therefore, as the same amount 

 occurring in the grains, because in the former case much more of 

 the nitrogen belongs to the non-albuminoid, or amide form. 



The true value of amides in animal nutrition is not well defined. 

 That the}' are wholly like albuminoids in oflEice seems hardly 

 probable, at least previous investigations do not show this. 



Crude fiber is the woody part of plants, and is that which remains 

 undissolved after treating vegetable substance with weak acids and 



