FACTORS INFLUENCING THE WORK OF THE HORSE 287 



idle horses and may be used advantageously for this purpose along with 

 other feed. With idle animals the chief need is not for net energy but for 

 heat to maintain the body temperature. As has been shown before (80), 

 the energy used up in mastication, digestion, and assimilation all takes 

 the form of heat and thus aids in warming the body. 



Net energy values of feeds per 100 Ibs. for horses 



These net energy values, given in the preceding table, should be used 

 instead of the net energy values for ruminants given in Chapter VI 

 (171), when it is desired to compute rations for horses by the Armsby 

 standard. (174) For most feeds it will be necessary to use the net 

 energy values for ruminants, since none are available for horses. 



448. Maintenance requirements of the horse. It is more difficult to de- 

 termine the minimum amount of nutrients needed to maintain the weight 

 of a horse than of the ox or sheep. This is due to the fact that any excess 

 of nutrients supplied the idle horse above maintenance will not usually be 

 wholly stored as flesh or fat, for confined horses, even those of quiet tem- 

 perament, dissipate more or less energy thru restlessness and moving 

 about, so that a ration which barely maintains them is really somewhat 

 in excess of the theoretical requirement. 



By feeding horses at first rations which were insufficient to maintain 

 their weights, and then gradually increasing the amount of feed until 

 the live weights were barely maintained, Grandeau and LeClerc 10 were 

 able to maintain horses on a ration of meadow hay which furnished 7 Ibs. 

 of digestible nutrients, or 13.1 therms of available energy, per 1,000 Ibs. 

 live weight. Using another method Zuntz and his colleagues 11 found that 

 for maintenance the horse needed 6.4 Ibs. digestible nutrients, or 11.9 

 therms of available energy per 1,000 Ibs. live weight. It was found that 

 the larger part of the nutrients, nearly 66 per ct., were required merely 

 as fuel to maintain the temperature of the body. Indeed, it was necessary 

 to supply only 2.43 Ibs. of net nutrients (or 4.1 therms of net energy) to 



^London Live Stock Jour., 1894, p. 9. 

 "Land. Jahrb., 27, 1898, Sup. Ill, pp. 422-426. 



