Investigations Concerning the Horse. 257 



work than during rest. (109) Hence, as Kellner^ points out, there 

 is a great similarity between the nutrient requirement of mature 

 working and mature fattening animals. After growth is completed 

 and the protein tissues and organs of the body have reached full 

 size, both working and fattening animals need only so much crude 

 protein in their food in excess of maintenance requirements as is 

 necessary to insure complete digestion of the ration. The re- 

 mainder of the nutrient requirements, whether for producing fat 

 with the ox or performing work with the horse, may be met thru a 

 sufficient supply of carbohydrates and fat. (97) Accordingly a nar- 

 row nutritive ratio is not essential with the work horse. (131) Gran- 

 deau and Alekan- found that when horses working at a trot were fed 

 rations of corn, sugar, and oat straw, furnishing but little crude 

 protein and having extremely wide ratios, varying from 1 : 21 to 

 1 : 28, the ration still contained sufficient digestible crude protein to 

 keep them in excellent condition. Kellner^ found that horses were 

 able to perform hard labor without deterioration on a ration having a 

 nutritive ratio of 1:9. Grandeau fed 3 horses during a whole year, 

 sometimes on a ration of horse beans and straw having a nutritive 

 ratio of 1:3, and again on one of Indian corn and straw having a 

 ratio of 1 : 10. While on these rations the horses were either resting 

 in the stall, exercising at a walk or trot, working on a sweep at a 

 walk or trot, or finally working before the carriage. The effect of 

 the rations was about the same in all cases, and any difference was 

 in favor of the corn-and-straw ration having the wider ratio. These 

 and other experiments, as well as practical experience, show that the 

 nutritive ratio for work horses may vary widely without injury so 

 long as the minimum requirement of crude protein is satisfied. 

 Kellner* states that the only exception to this rule are animals which 

 have not finished their growth and those undergoing severe exertion 

 at a rapid pace. Such exertion necessitates an unusually abundant 

 supply of oxygen to the muscles. Hence the blood, which is the car- 

 rier of oxygen, should be increased in quantity to a certain extent, 

 and this can be brought about only thru a liberal supply of crude 

 protein. Experience has shown that a nutritive ratio as narrow as 

 1 : 7 is sufficient for this purpose. Horses which are in low condi- 

 tion and must gain in weight and muscle before they are fit for 

 hard work must of course receive a liberal supply of crude protein, 



^ Ernahr. landw. Nutztiere, 1907, p. 443. ^ Landw. Jahrb., 9, p. 665. 



* Ann. Sci. Agron., 1901, II, p. 38. * Ernahr. landw. Nutztiere, 1907, p. 430, 



