DYNAMICS 159 



readily, except on the very finest pastures, even if they have 

 an unlimited area at their disposal, unless they are also given 

 a certain amount of readily digestible cakes and meals. 



Pecuniary Considerations. These considerations are also 

 of importance from a pecuniary point of view. The cost of 

 the various foods per 1000 kt. of dynamic energy is shown in 

 the last column of the tables (p. 166). It will be seen that in 

 this case also roots come out near the top, but owing to their 

 bulky and watery character they cannot be largely used as 

 rations for working horses. Of the dry foods, rape cake is 

 distinctly the cheapest at the prices assumed. It is closely 

 followed by rice-meal, maize, bran, pollards, and locust beans. 

 All of these yield dynamic energy at a cost of about i per 

 1000 kt., but with the exception of rape cake they are all 

 rather deficient in nitrogen. Decorticated cotton cake, soya- 

 bean cake, and linseed cake cost about 235.10 25^., and barley, 

 wheat, and oats from 255. to 30.$-. per 1000 kt. Of the cereals, 

 rye, at 22.$-., is the cheapest, and oats, at 30^. per 1000 kt., 

 the dearest. Undecorticated cotton cakes, hay and straws are 

 all more expensive as a source of dynamic energy. 



The position of the coarse fodders hay and straw is of 

 peculiar interest from this point of view. It was shown 

 (p. 142) that they are amongst the cheapest foods for main- 

 tenance, because the whole of the energy of the digestible 

 matter is available for that purpose ; but because so much is 

 spent in the work of digestion they are amongst the most 

 expensive substances as a source of dynamic energy. Straws, 

 it will be noticed, are markedly inferior to hay in this respect. 

 The quality of the hay, too, makes a much greater difference 

 to the cost of the dynamic energy than to that of the thermic. 

 The price of the best quality of meadow hay works out to 

 about 22S. and that of the inferior to 30 s. per 1000 kt. of 

 dynamic energy truly a case where the best is the cheapest ; 

 whereas at the prices quoted the inferior quality is rather 

 cheaper than the best as a source of thermic energy. 



The general conclusion to be drawn from these data is that 

 the energy required for the performance of work apart 

 from the simple maintenance of the animal can be most 



