14 SCIENTIFIC FEEDING OF ANIMALS 



per ties. The various kinds of straw, the awns and 

 husks of grains, and the varieties of hay, etc., are 

 richest in crude fibre, as is seen in Table I of the 

 Appendix. On the other hand, roots and tubers, awn- 

 less seeds of cereals, and most of the seeds freed from 

 husks, contain only a little. Foods of animal origin, 

 and also molasses, are practically free from fibre. 



(6) The nitrogen-free extract. 

 Under the above designation are included all 

 those constituents of feeding-stuffs which do not 

 belong to any of the groups already mentioned, 

 or are not mineral substances. The percentage 

 amount of nitrogen-free extract in any food is 

 therefore found by adding together the percentage 

 of water, crude protein, fat, crude fibre, and ash, 

 and subtracting them from ioo. It is impossible, 

 owing to the great differences found amongst the 

 nitrogen-free extract substances, to determine them 

 directly. In this group it is usual to include (i) 

 carbohydrates, (2) pentosans, (3) incrusting ma- 

 terials, (4) organic acids. The carbohydrates, 

 which are the chief representatives of the nitrogen- 

 free extract substances, include glucose or grape 

 sugar, levulose or fruit sugar, saccharose or cane 

 sugar, lactose or milk sugar, starch, and the dex- 

 trines. All members of the group which are not 

 already classified as sugars are converted into them 

 by boiling with dilute acids, grape sugar or fruit 



