THE CHEMICAL COMPOSITION OF FOODS 17 



of fact, such is not the case, for the work expended in 

 chewing, churning, propelling, and digesting such a 

 coarse food as wheat-straw is greater than that supplied 

 by its digestible constituents, and, fed alone to a horse, 

 it is insufficient, in any quantity that the animal can 

 eat, to maintain the animal even at rest. In order, then, 

 to arrive at the real value of the crude fibre in a ration, 

 an adjustment has to be made between the benefit 

 derived from the digestible portion and the loss of 

 energy incurred in dealing with the indigestible woody 

 portion. Thus in practice it may be said that the 

 " crude fibre " in a food is of comparatively little 

 nutritive (as apart from its mechanical mass) value to 

 a icorhing horse. At the same time, the fibrous part 

 of a food has an important function in supplying bulk in 

 the intestines, and in the case of some foods deficient 

 in fibre, such as maize, a more fibrous material, like 

 timothy hay, has to be fed along with them to allow of 

 a proper movement of the ingesta along the bowel. Thus, 

 whilst an excess of crude fibre in a ration is innutritions, 

 and may even actually lessen the value to the animal 

 of the other nutritive constituents, a certain amount is 

 valuable and necessary. Sometimes the crude fibre of 

 plants may exist in the form of hairs or wool-like fibres, 

 and these may be dangerous, if in large amount, by 

 tending to clump or felt together, so forming concretions 

 or calculi in the intestine — e.g., as in undecorticated 

 cotton-cake. In buying food substances an analysis 

 revealing a high percentage of fibre would suggest a 

 food of low value and correspondingly low price, for some 

 more concentrated, less fibrous, and more expensive food- 

 stuff would be required to bring it up to the standard for 

 a horse. 



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