260 Feeds and Feeding. 



of the energy expended for draft was utilized in the work performed. 

 When performing draft up that grade more work was done per 

 minute, and this led to an increase in the rapidity of breathing and 

 the over-exertion of certain groups of muscles, with the result that 

 more energy was wasted as heat and less was utilized in moving the 

 load. 



402. Net nutrients needed in work. Zuntz, studying the 1100-lb. 

 horse carrying a 44-lb. harness, found the net nutrients (70) re- 

 quired for the performance of various kinds of work, in addition to 

 those required for maintenance, to be as follows: 



Net nutrients 

 required 



Troweling 1 mile on the level Lbs. 



At a walking speed of 2.5 miles per hour ._. 0.134 



At a walking speed of 3. 5 miles per hour 0. 169 



At a trotting speed of 6. 6 to 7.6 miles per hour 0.254 



Traveling 1 mile when carrying a load of 220 Ibs. at 



Walking speed of 3. 4 miles per hour 0.210 



Trotting speed of 6. 9 miles per hour . . . 0. 323 



Raising his body 100 feet 



In climbing incline of 10. 7 per cent 0.060 



In climbing incline of 18. 1 per cent 0.062 



Lowering body 100 ft. on a road with a 5 per cent dip, compared with 



traveling on the level, saves 0.025 



Work of ascent per 1000 ft.-tons 



On an incline of 10. 7 percent 1.050 



On an incline of 18. 1 per cent 1.072 



Draft on level per 1000 ft.-tons, not including locomotion of body... 1.157 



By means of the above table a given amount of work done by the 

 horse may be resolved into its factors, so that the nutrients required 

 for its production may be estimated and a suitable ration formed. 

 The table is of theoretical rather than practical interest, however, 

 because the work of most horses varies greatly from day to day; con- 

 sequently it is impossible to more than roughly set forth the nutri- 

 ents required. 



Kellner 1 expresses in starch values the net nutrient requirement of 

 the 1100-lb. working horse as follows: 



Starch values 



Light work 10. 1 pounds 



Medium work 12.8 pounds 



Hard work... _ 16.5 pounds 



403. True value of feeds. The true value of different feeds for 

 the horse is not based merely on their content of digestible nutrients, 

 since, as we have seen, a varying percentage of their total energy is 



1 Ernahr. landw. Nutztiere, 1907, p. 453. 



