CONSTITUENTS OF FOOD. 97 



less inert vehicle, of which vegetable fibre is the natural and 

 best form, disturbance of the digestive organs will ensue. The 

 mechanical action of fibre in this respect is generally put 

 down to its bulk-giving properties, on the supposition that 

 a horse is unable to digest a food that is not bulky. We 

 know that absence of concentration is more essential than 

 bulk ; for if an animal is put on, say, the starvation and 

 non-bulky diet of 2 quarts of ordinary oats and 2 quarts 

 of chopped hay, he will digest it in a normal manner ; 

 although in all probability his digestion would be upset by 

 double that bulk (8 quarts) of oats from which the husk 

 (mostly woody fibre) had been removed. We find that the 

 wholesomeness (p. 72) of different samples of oats varies 

 according to their respective percentages of husk, other con- 

 ditions being equal, when this grain is given without other 

 food ; and that, in such a case, a horse can consume in a 

 healthy manner a moderate quantity of oats which has a fair 

 proportion of husk, but is unable to do so if the husk is 

 absent. Again, maize, which has almost the same composition 

 as oats, except that it contains less fibre and mineral matter, 

 requires for its healthy digestion the addition of more " chop " 

 than do oats. In fact, by adding fibre to maize (for instance, 

 by grinding up the grain and cob together, so as to make the 

 fibre percentage of the mixture about equal to that of oats), 

 we can render maize nearly if not quite as wholesome a food 

 as oats. It is evident that the arrangement by which each 

 kernel of oats is surrounded by a comparatively thick 

 covering rich in fibre, greatly promotes the wholesomeness 

 of that grain. The custom of mixing chopped hay with oats 

 has long been an unconscious recognition of the truth of the 

 principle in question, which principle is also more or less 

 carried out when the animal is allowed hay at feeding time. 



From the foregoing observations we come to the important 

 law, that the percentage of fibre in a horse's hay should be 



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