9 



up the beating of the heart, circulation of the blood, respiratory move- 

 ments, and other vital processes; (2) the energy which is expended in 

 moving the body, walking', trotting, etc., which is usually spoken of 

 as energy required for forward progression; and (3) the energy which 

 is expended in carrying a rider, as in the case of a saddle horse, or 

 drawing a load, as in the case of a draft animal or carriage horse. 



The character of the road, whether level or up or down hill, is an 

 important factor in determining the amount of work. It is evident 

 that more energy is required to lift the body at each step and move it 

 forward when climbing an incline than when walking on a level. In 

 the same way, when a load is drawn uphill it must be raised as well as 

 drawn forward. 



Work may be measured as foot-pounds or foot-tons, or by any other 

 convenient unit. A foot-j)ound is the amount of energy expended in 

 raising 1 pound 1 foot; a foot-ton, that expended in raising 1 ton 1 

 foot; a commonly used unit of force is the "ton power," equivalent 

 to 550 foot-pounds per second. Work may also be measured in terms 

 of heat, i, e., calories. This is especially convenient in discussing 

 problems of nutrition, since the heat of combustion is one of the factors 

 usually determined or calculated when foods are analyzed; and further- 

 more, the feeding standards which have been proposed for horses and 

 other farm animals show the requirements per day in terms of nutri- 

 ents and energy. One calorie corresponds, as stated above, very 

 nearly to 1.54 foot-tons. 



COMPOSITION OF FEEDING STUFFS. 



The feeding stuffs of most importance for horses are cereal grains, 

 such as oats and corn, either ground or unground; leguminous seeds, 

 as beans and peas; cakes, and other commercial by-products, as oil- 

 cake, gluten feed, and so on; fodder crops, green or cured; and differ- 

 ent roots, tubers, and green vegetables. In quite recent times cane 

 molasses, beet molasses, and other beet-sugar by-products have 

 assumed more or less importance in this connection. The composition 

 of a number of these different feeding stuffs ma}^ be seen by reference 

 to Table 1, which shows the average composition as determined by 

 anal3"sis, and when possible the digestible nutrients furnished by each 

 100 pounds of the feeding stuffs, the latter data having been calculated 

 ])y the aid of figures obtained in digestion experiments with horses. 

 In a number of cases such calculations have not been made, for the 

 reason that experiments showing the digestibility of the feeding stuffs 

 have not been found, nor were results of experiments made with 

 similar feeding stuffs available. The comparatively large number of 

 feeding stuffs of which the digestibilit}^ has not been determined indi- 

 cates one of the lines of work which might be profitably followed. 



170 



