16 THE ECONOMICS OF FEEDING HORSES 



oxygen, the action gives rise to the same (total) 

 amount of heat, and to the same new substances or 

 compounds. Thus, whether 1 ounce of fat (tallow) is 

 burned in the form of a candle, or absorbed from the 

 digestive tract of an animal into the blood-stream and 

 oxidised there by the inspired oxygen present in the 

 blood, the total amount of heat produced is the same, 

 and the same compounds, carbon dioxide and water, 

 result. The greater the amount of oxygen required to 

 completely burn up or oxidise a substance, the more 

 heat is produced; and it is because fats require more 

 oxidising than carbo-hydrates that fats supply more heat 

 to the body than the same weight of carbo-hydrates. 



The Crude Fibre is that part of the food which is of 

 a more or less woody nature, and consists chiefly of 

 cellulose derivatives, such as lignin and cutin. It is found 

 chiefly in the husks of seeds and woody stems of plants, 

 and a large part of it is quite incapable of digestion by the 

 horse. Cattle and sheep are able to digest a much larger 

 proportion of the crude fibre in the foods supplied to them, 

 and thus can make good use of such fibrous materials as 

 oat-straw and undecorticated cotton-cake. The horse, 

 however, with his limited ability to digest crude fibre, 

 would actually starve on food which would nourish an 

 ox. Of the total substance included under the term 

 "crude fibre," there is, then, a digestible and an in- 

 digestible portion, and the former appears to have a 

 nutritive value similar to that of starch. Thus, in a food 

 such as wheat- straw, containing about 40 per cent, of 

 crude fibre, of which something like one-seventh is 

 digested, it would appear as though 6 pounds of digested 

 cellulose, with a nutritive value equal to that of starch, 

 should be added to the value of the food. As a matter 



