FACTORS INFLUENCING THE WORK OF THE HORSE 285 



For a short time a horse can exert a pull of about one-half its weight. 

 The ox draws a load equal to the horse, but ordinarily at only two-thirds 

 the speed. A man 's work is usually from one-sixth to one-tenth of a horse 

 power, or about one-fifth that of an average horse. For a minute or two 

 he can exert a full horse power or even more. 



The character of the road bed is a most important factor in determin- 

 ing how heavy a load a horse can draw. The following table shows the 

 draft required per ton of load, including the weight of the wagon, to 

 haul a 4-wheeled wagon on various types of level road. 3 



Draft required to haul a wagon on various types of road 



Draft per ton Draft per ton 



Character of road Lba. Character of road Lbs. 



Wood block, good 33 Vitrified brick 55 



Sheet asphalt, good 38 Oiled road, dry 61 



Macadam, average 46 Earth, packed and dry 100 



Gravel, good 51 Earth, muddy 190 



Cobblestone 54 Sand, loose 320 



The table shows that it requires a draft, or pull, of only about 33 Ibs., 

 as measured by a dynamometer, a crude form of which is a spring balance 

 placed between horse and load, to draw a load of a ton, including wagon, 

 on a good wood block road and of 38 Ibs. on a sheet asphalt roadway. On 

 poor roads the draft is many times greater, being 190 Ibs. on a muddy 

 earth road and 320 Ibs. on loose sand. 



445. Digestion trials. Since there have been relatively few digestion 

 trials with the horse, we are usually obliged to use for this animal the 

 coefficients of digestibility obtained with the ox or sheep. (66) While the 

 horse digests the easily digested feeds about as completely as do the 

 ruminants, it falls below them in ability to digest the more difficultly di- 

 gested ones. This is shown by the digestion coefficients for typical feeds 

 given in Appendix Table II of this book. The horse digests 88 per ct. of 

 the dry matter in corn and ruminants 90 per ct. On the other hand, 

 the horse digests only 44 per ct. of the dry matter of timothy hay, while 

 ruminants digest 58 per ct. (85) 



446. Influence of work on digestibility. The effect of working a horse 

 immediately after eating has been studied by Grandeau and LeClerc, 4 

 Tangl, 5 Colin, 8 Scheunert 7 and others. Their investigations show that 

 moderate exercise, even immediately after the horse has eaten, tends to 

 increase digestion in both the stomach and the small intestine, and also 

 increases the rate of absorption of digested nutrients. Tho the rate of 

 protein digestion is retarded for the first hour after eating, when the 

 horse is exercised immediately after the meal, by the end of the second 



*Agg, Construction of Eoads and Pavements, p. 343. 

 * Ann. Sci. Agron., 1884, Vol. II, p. 235. 

 cpfliiger's Arch. Physiol., 63, 1896, p. 545. 

 eTraite Physiol. Comp. Anim., 1886, p. 822. 

 7 Pfliiger's Arch. Physiol., 109, 1905, p. 145-198. 



