138 PRINCIPLES OF FEEDING FARM ANIMALS 



as work is done at the expense of the carbohydrates and fats 

 of the ration, theoreticall}' the amount of protein suppHed 

 for the maintenance of a horse should be sufficient for the 

 same horse when doing work, as work is done primarily 

 at the expense of the carbohydrates and fat of the feed, the 

 protein not being drawn upon as long as the other nutrients 

 are present in sufficient amounts. However, in actual 

 practice, usually it is desirable to feed more protein than the 

 maintenance requirement, because, as we have already seen, 

 a ration with a very \\ade nutritive ratio is not as thoroughly 

 digested as one containing more protein. Kellner states 

 that a nutritive ratio of 1 : 8 or 1 : 10 is sufficient to prevent 

 any decrease in the digestibility of the ration. 



The requirements for mature work horses are given in 

 the Wolff-Lehmann, the Henry-Morrison, and the Kellner 

 standards. For convenience, we have followed the custom 

 of Armsby and expressed the Kellner standard in terms of 

 digestible protein and net energy. The Kellner standard 

 for a 1000-lb. horse, thus expressed, is given in Table 15. 



Table 15. — Requirements of Work Horses (Kellner) 



Total Dry Digestible 

 Substance Protein 



i Lb. Lb. 



Light work 18-23 1.2 



Medium work 21-26 1.6 



Heavy work 23-28 2.2 



Net 

 Energy 



Thrrm.'i 

 9 8 



12.4 

 16.0 



Any of these standards should be valuable. 



H should be borne in mind that, on account of his limited 

 digestive capacity, the horse, especially when doing hard 



