MAKtJAL OF CATTLE-FEEDING. 253 



matter of the fodder, except tlie fat, as composed of carT> 

 liydrates and as liaving tlie same functions in nutrition as 

 sugar and starch have been proved to have in the experi- 

 ments whicli have been detailed in Fart I. 



Gomposition of Undigested Nitrogen-free Extract. 

 — The part of the nitrogen-free extract which remains 

 nndigested is a -mixture of various su])stance8 richer in 

 carbon than the carbhydrates and having, as a whole, 

 nearly the percentage composition of lignin, as given on 

 p. 39. 



It is therefore a matter of comparative indifference in 

 fodder analyses, whether the lignin dissolves in the acid 

 and alkaline liquids used to isolate the cellulose or remains 

 with the latter as incrusting substance. In one case it ap- 

 pears in the results of analyses as part of the nitrograi-fiee 

 extract, in the other, as crude fibre ; in both cases it reap- 

 pears in the excrements and leaves the total quantitj and 

 quality of the digested nutrients the same, and the only 

 effect of a variation of this sort w^ould be on the compen- 

 sation between the undigested extract and the digested 

 fibre. 



The AqneoTis Extract. — From the numerous experi- 

 ments executed in "Weende on oxen and sheep, the law has 

 been deduced that the total quantity of solid matter that 

 can be extracted from a fodder by boiling water, i, e.j the 

 aqueous extract, is a measure of the digestible portion of 

 the nitrogen-fi^ee extract. In single cases, however, con- 

 siderable variations from the rule were observed on both 

 sides of the average, amounting to as much as 14 per 

 cent. 



This method of judging of the quality of coarse fodder 

 has not found any general application, for the reason that 

 no necessary connection exists between tlie digestible ni- 



