HORSE FEEDING. 5 



MEASUREMENT OF THE WORK PERFORMED BY HORSES. 



The chief aim in horse-feeding experiments is to learn the amount 

 of nutrients which the animal body, considered as a machine, requires 

 for work. This requires an estimate or measurement of the amount 

 of work performed. Such measurements in the case of draft horses 

 can readily be made with a dynamometer. The measurement of the 

 energy expended by a saddle horse, however, is a different matter. In 

 the opinion of cavalry officers who have studied this question, meas- 

 uring the distance covered and the rate of speed is practically the only 

 method available. According to Marcy, who has devoted considerable 

 attention to the subject, the work accomplished in a given time is pro- 

 portionate to the square of the velocity. His coefficients were 3.42 

 for walking or pacing, 10 for trotting, 28.62 for cantering, and 68.39 

 for a full gallop. That is to say, -ii times as much work is performed 

 when trotting as when walking. If times as much when cantering as 

 when trotting, and 2^ times as much when on a full gallop as on an 

 ordinary gallop or canter. These are only general statements, and it 

 is impossible as yet to calculate the actual energy expended by saddle 

 horses carrying their riders at different gaits. 



It has been suggested that it may l)e possible to gain an idea of the 

 energy expended by noting the number of pulsations of the flank, 

 which has been found to vary with the gait and with the grade and 

 character of the surface passed over. It is evident that in the case of 

 saddle horses, useful work depends largel}' upon the speed, since the 

 quantity of work of which the animal is capable diminishes with 

 increased speed. In the same way it has been found with draft horses 

 that the period for which work can be continued diminishes as the 

 speed increases. The conditions under which the work is done are also 

 of importance. External temperature may be mentioned, as well as 

 the conditions of the surface traveled over, the skill of the driver, the 

 methods of harnessing, and the load which must be drawn. Poncelet 

 estimates that a horse carrying a weight of 120 kg. and traveling at a 

 speed of 1.1 meters per second for 10 hours per day performs 4,752,000 

 kilogrammeters of work. When the weight borne equals 80 kg., the 

 same horse trotting at the rate of 2.2 meters per second for 7 hours 

 per day performs 4,435,000 kilogrammeters of work. 



Ellenberger estimates that the Prussian cavalry horse performs 

 1,500,000 kilogrammeters of useful work daily during the winter 

 «nonths, when less is required of horses than at other seasons. In the 

 spring and summer the preparation for the military maneuvers 

 increases this quantity 200,000 kilogrammeters daih\ According to 

 the same author, when a horse travels from 24 to 34 kilometers per 

 day and carries a load of 110 to 125 kg., the energy expended is equiv- 

 alent to from 300,000 to 500,000 kilogrammeters of work. These 



