b7 



than less through a long- period. Rations which will furnish the 

 amounts called for by other feeding standards, or by the average 

 values deduced from American rations, can, of course, be calculated 

 in the same way. As will be noted, the amount of feeding stuffs 

 necessar}^ to provide nutrients equal to the amount called for by the 

 Wolff standard for a horse at moderate work is large compared with 

 the amounts f)rdinarily used in this country. 



MUSCULAR WORK AND ITS EFFECT ON FOOD REQUIREMENTS. 



It is commonly said that the amount of food required l)}^ horses is 

 proportionate to their weight; it being self-evident that a large horse 

 would require more material than a small horse to build and repair 

 the body and to carry on all the vital processes which constitute 

 internal muscular work. Investigations have shown that the require- 

 ments are more nearly proportional to the surface areas than to the 

 body weight. Individual peculiarity is, of course, a factor which 

 must be reckoned with, but the general statement is justified. The 

 factor which has the greatest influence on the ration required is the 

 amount of work performed, the ration increasing with the work. 

 When horses M'hich have been consuming a large ration and perform- 

 ing work are compelled to rest, even for a few days, the ration should 

 be diminished. 



In order to study the effects of work upon the amount of food 

 required it is necessary to have some means of measuring and com- 

 paring the different kinds of work done. 



MEASURING MUSCULAR VORK. 



It has been said alread}- that the total work performed by a norse 

 consists of internal and external muscular exertion. The former 

 includes the force expended in the digesting of food, the beating of 

 the heart, etc.; the latter that expended in moving the body, i. e., in 

 the motion of forward progression, and in drawing or carrying a load. 

 The latter factor is the one of most importance in considering the horse 

 as a beast of burden. The amount of such muscular work has been cal- 

 culated or measured in various ways. The methods of calculation are 

 often complex and need not be discussed in detail. 



According to the classic experiments of James Watts, a horse can 

 exert a power equal to 33,000 foot-pounds per minute, i. e., in one min- 

 ute can exert a force sufficient to raise 33,000 pounds 1 foot. This value 

 has been termed one horsepower and has been accepted as a common 

 unit for the measurement of force. In countries where the metric 

 system is employed the more common unit is the kilogrammeter. 

 This unit is equal to 7.2 foot-pounds. According to Watts's values, a 

 horse working eight hours per day would perform work represented 

 by 33,000 X 60 X 8 = 15,81:0,000 foot-pounds. Later estimates give 



170 



