392 PRINCIPLES OF ANIMAL NUTRITION. 
the method described on pp. 76 and 252. The following is a sum- 
mary of the results computed per kilogram of feed: 
No. of Oxygen CO, Equivalent 
Fodder. Experi- Consumed, Exereted, nergy, 
ments. Liters. Liters. 
Oats and cut straw (6:1).... 8 12.964 10.679 64.17 
BY cavayiekes 3 sissvsices a: cue opscede re. sed wu 8 33.840 27.813 167.44 
Hay, cate, and cul .....W 8 20.072 17.677 100.79 
Maize and cut straw (6: 1). 2 7.133 6.205 35.72 
Green alfalfa................ 7 6.171 4.980 30.42 
Computed for oats alone: i441 wiles vanes es | Seas viewers saw nis Ges 47.00 
“ maize alone ...|.........|.......--. |. ee esse. 13.80 
As was to have been expected, the work of mastication proves 
to be much greater in the case of hay than in that of grain. Maize 
gave a remarkably low result, while the lowest was obtained with 
green fodder. Even when the results on the latter are computed 
per kilogram of dry matter, they are still about 40 per cent. lower 
than those on hay. A few experiments on old horses with defect- 
ive teeth gave somewhat higher results for the mixture of oats 
and cut straw. 
The absolute amount of energy expended in mastication, etc., is 
very considerable. On the average of three periods,:on a ration 
consisting of 5.6 kgs. of oats, 0.93 kgs. of cut straw, and 5.18 kgs. 
of hay, it is computed at 1287.1 Cals., an amount equal to 11.2 per 
cent. of the total metabolism during rest 
ConcLusions.—The researches of Zuntz & Hagemann are of 
great value in that they demonstrate the large proportion of the 
energy of the food which is consumed in its prehension, mastication, 
digestion, and assimilation in the case of herbivorous animals, and 
that this proportion is largely influenced by the physical character 
of the food. Thus the hard but brittle maize required much less 
energy for its mastication than the softer but tougher and more 
woody oats, and the dry matter of the green alfalfa decidedly less 
than that of the hay. These results indicate quite clearly that no 
accurate estimates of the work of mastication can (at least in the 
present state of our knowledge) be based on the chemical compo- 
sition of feeding-stuffs. As noted above, Zuntz & Hagemann 
attempt to compute the work of digestion upon that basis. It 
