668 



NUTRITION OF FARM ANIMALS 



of the starch or fat which was recovered as useful work and 

 called attention to the desirability of determinations of the 

 heats of combustion of nutrients and feeding stuffs. Sixteen 

 years later, after Rubner had published his fundamental work 

 on the replacement values of nutrients, and Zuntz and his as- 

 sociates (385, 651-656) had begun their investigations upon the 

 metabolism of the horse from the standpoint of energy, Kellner 

 was able to return to the subject and undertake the extensive 

 investigations with cattle frequently cited on previous pages. 



769. Energy values of digestible nutrients. Taking as his 

 point of departure the digestible nutrients of feeding stuffs, 

 Kellner sought first to determine the net energy values of the 

 digestible protein, carbohydrates and fats for cattle by adding 

 these substances in as pure form as possible to a basal ration in 

 the manner already described (449). The results with cattle 

 obtained in this way on starch, straw pulp, sugar, wheat gluten 

 and oil are included in Table 202 (760) . In that table, however, 

 these materials are regarded in the light of feeding stuffs and 

 the energy losses and net energy values relate to the substance 

 as a whole and include all its effects. For his purpose, how- 

 ever, Kellner computed the net energy values, not of these sub- 

 stances as a whole but of the protein, carbohydrates and fat 

 which determinations of digestibility showed to have been 

 resorbed from them, with the following results. 1 



TABLE 205. NET ENERGY VALUES OF DIGESTIBLE NUTRIENTS FOR 



CATTLE 



. Vers. Stat., 63 (1900), 1-474; Ernahrung landw. Nutztiere, 6th Ed. 



95-159- 



