MAINTENANCE RATIONS OF HORSES. 



55 



an approximate average utilization of 74.5 per cent of the meta- 

 bolizable energy supplied in excess of the fasting katabolism. If 

 we may apply this percentage to the average of the foregoing results 

 regarding maintenance, we may compute the average requirement 

 of available energy to be 2.243X0.745=1.671 therms per 50 kilo- 

 grams, or 1.566 therms per 100 pounds, a result not differing very 

 widely from the figures computed on a previous page from the results 

 of experiments on the fasting katabolism, but with a very wide 

 range of variation in individual cases. 



THE HORSE. 



The maintenance ration of the horse has been the subject of inves- 

 tigation by Zuntz and Hagemann, Wolff, Miintz, and Grandeau and 

 Le Clerc. 



ZUN1Z AND HAGEM ANN'S INVESTIGATIONS. 



Upon the basis of the results regarding the availability of energy 

 for the horse, which have been described on pages 22-25, Zuntz and 

 Hagemann 1 compute the fasting katabolism of the horse by sub- 

 stantially the same method as that employed on pages 34-35 for cattle. 



For this purpose, they use those rest experiuieuts ou horse III iu which 

 the feed consisted of oats, hay, and straw. From the results of the respira- 

 tion experiments made within the first five hours after feeding, they compute 

 the total energy katabolism per day in the manner indicated on page 22, and 

 from this subtract the energy expended in the digestion of the feed (not 

 including the work of mastication), computed as shown on page 23. The 

 remainder, of course, is the katabolism due to internal work, together with any 

 katabolism resulting from a possible demand for heat to maintain the body 

 temperature. Their results may be tabulated as follows : 



Computed fasting katabolism of horse per dan and head — Zuntz and Hage- 

 mann' s experiments. 





Live 

 weight. 



Energy 

 katabo- 

 lism. 



Oats. 



Feed. 

 Straw. 



Hay. 



Work of 

 digestion. 



Fasting 

 katabo- 

 lism. 



Fasting 

 katabo- 

 lism per 

 square 

 centime- 

 ter body 

 surface. 



Season. 



















Gram- 







Kilos. 



Therms. 



Kilos. 



Kilos. 



Kilos. 



Therms. 



Therms. 



calories. 





Period a 



428.1 



12. 541 



6 



1 



7 



8.403 



4. 138 



80.7 



Winter. 



Period b 



434.1 



11.674 



6 



1 



6 



7. 704 



3. 970 



76.7 



Summer. 



Period e 



450.4 



12. 364 



6 



1 



6 



7. 704 



4. 660 



87.9 



Winter. 



Period/ 



449.1 



11. 783 



6 



1 



4. 75 



6. 830 



4. 953 



93.6 



Summer. 



Period i 



440.1 



11. 893 



6 



1 



6 



7. 704 



4. 189 



80.2 



Winter. 



Period n 



448.2 



11. 407 



£ 8 





5.1 



5.672 



5. 735 



108.5 



Summer. 



Period c 



442.2 



12. 450 







s 



10.5 



7. 340 



5.110 



97.6 



Do. 



Period No. 118c 



434.6 



11.021 



4.8 



0.8 



1.88 



4. 122 



6. 899 



133. 3 



Winter. 



In the experiments with a standard ration of 6 kilograms of oats, 

 1 of straw, and 6 (or 7) of hay, the average computed fasting katab- 

 olism for the three winter periods is 4.329 therms, while in the 



1 Loc. cit., pp. 283-284 and 425-426. 



