566 NUTRITION OF FARM ANIMALS 



reported, although the indications are (659) that it is not widely 

 different from that of the horse. 



Using the net energy values for the horse obtained by Zuntz and 

 Hagemann's method of computation and contained in Table VIII 

 of the Appendix, rations may readily be computed for this animal 

 in the same general manner as for any other, their accuracy de- 

 pending upon the accuracy of the net energy values used. Thus, 

 in the case just supposed, the requirement of net energy was 

 17.254 Therms. From the figures of the table it is easy to com- 

 pute that the following ration would meet the requirement. 



TABLE 160. EXAMPLE OF RATION FOR WORK 



NET ENERGY 



10 Ib. meadow hay 3. 270 Therms 



10 Ib. oats 8.820 Therms 



4.1 Ib. maize 5.164 Therms 



17.254 Therms 



The principal difficulty in practice lies in the determination 

 of the amount of work done. With farm animals doing a va- 

 riety of work at more or less irregular intervals, it seems hardly 

 possible to make any computation of the mechanical work 

 performed which would be trustworthy or which would justify 

 the time consumed. The sufficiency of the ration of the farm 

 horse will ordinarily be judged of by the live weight and con- 

 dition of the animal, and the principal use of tables of net energy 

 values will be as an aid in securing the necessary feed energy 

 at the cheapest rate per unit. 



On the other hand, where a large number of horses or mules 

 are used for the same kind of work under uniform conditions it 

 would seem possible to make fairly reliable estimates of the 

 work done and to compute feed requirements with a reasonable 

 degree of accuracy. It appears not unlikely that such compu- 

 tations might lead to considerable economy, since, as was pointed 

 out in considering the maintenance requirements of the horse 

 (392), a surplus of feed seems especially apt to stimulate this 

 animal to restlessness and an unnecessary expenditure of en- 

 ergy in minor muscular activities. 



674. Feeding standards for the horse. More or less ar- 

 bitrary estimates for light, medium, and heavy work may also 

 be formulated, as has been done by various writers. 



