FACTORS INFLUENCING THE WORK OF THE HORSE 291 



McCampbell 14 of the Kansas Station studied this question in his ex- 

 periments at Fort Riley, the most extensive yet carried on with horses in 

 the United States. From trials in which prairie hay and corn were fed 

 with and without a nitrogenous supplement, he concludes that a ration 

 having a wider nutritive ratio than 1 :8 is inadvisable. It is not necessary 

 to employ protein-rich concentrates to secure this nutritive ratio when 

 legume hay forms the larger part of the roughage allowance. 



455. Computing rations for work horses. The amount of energy ex- 

 pended by horses in each of the types of work they do has been deter- 

 mined with considerable exactness in the investigations of Zuntz and 

 others which have been referred to in the previous paragraphs. How- 

 ever, the results are of theoretical rather than practical interest, for the 

 work of most horses varies greatly from day to day and is usually of a 

 complex nature, difficult to divide into these simple types. All that can 

 commonly be done is to estimate whether the horse is performing light, 

 medium, or heavy work, and then compute a ration which meets the 

 standard for this degree of labor. A horse actually working about 7 

 hours a day or more at reasonably hard labor, should be considered at 

 hard work, while one which works but 3 to 4 hours a day should be classed 

 as at medium work, unless the work is unusually severe or is performed 

 at a rapid rate. Horses working less than this are at light work. Such a 

 rough classification will suffice as a guide in computing approximate 

 balanced rations for work horses. The amount of concentrates fed to 

 the individual horses should be adjusted so as to maintain them in the de- 

 sired condition, as further discussed in Article 530. 



The older feeding standards prescribe more total digestible nutrients 

 or net energy than actually seem to be required for draft horses doing 

 ordinary farm or city work. From a study of rations fed horses in 

 feeding trials at the Wisconsin 15 and other 16 experiment stations, and of 

 rations used in large stables, the recommendations given in the Morrison 

 (Modified Wolff -Lehmann) feeding standards have been formulated. 

 These are given in Appendix Table V. 



It is believed that these standards will be found to meet American con- 

 ditions satisfactorily. It will be noted that the allowance of total digest- 

 ible nutrients for the horse at hard work is nearly double that for the idle 

 horse, while the amount of dry matter is increased to a much less extent. 

 This means that the ration must consist more largely of concentrates as the 

 work becomes harder. A narrower nutritive ratio is recommended as the 

 severity of the work increases, for the horse at severe labor seems to be 

 benefited by a fairly liberal supply of protein. As is pointed out in a 

 later chapter, it is imperative that the concentrate allowance of hard- 

 worked horses be reduced on days when they are idle, or azoturia may 

 result. (530) 



14 Kan. Bui. 186. 



18 Wis. Bui. 302, pp. 63-4; unpublished data. 



16 Kan. Bui. 186; 111. Bui. 150; Ohio Bui. 195; N. H. Bui. 82; etc. 



