Purchased Food, and of its Residue as Manwe. 215 
kind, but weighing only from 3 to 4 lbs., and everybody knows 
that abnormally big roots possess very little feeding-value. Or 
if we compare the practical feeding value of beans and peas on 
the one hand, with wheat or oats on the other, we do not find 
the fattening qualities, or the power to produce butcher's meat, 
of leguminous seeds superior to those of the cereal grains men- 
tioned, although the former contain about twice as large a pro- 
portion of nitrogenous compounds as the latter. 
Again, the nutritive or fattening value of various kinds of 
oilcakes does not depend so much upon the relative proportions 
of albuminous or nitrogenous substances in them, as upon the 
larger or smaller amount of readily digestible non-nitrogenous 
food-constituents which they severally contain. If it were 
otherwise, decorticated cotton-cake, which contains fully 2 per 
cent, more nitrogen than the best linseed-cake, would have been 
found in practice more valuable for feeding purposes than the 
latter, which we know is not the case ; and rape-cake also 
would have to be regarded as superior to linseed^cake in feeding 
Talue. 
Woody Fibre. — The least valuable of the constituents of cattle- 
food is woody fibre. Bulky feeding materials, such as straw 
and chaff, and certain kinds of mill-refuse obtained in preparing 
wheaten flour, oatmeal, rice, &c., for human consumption, con- 
tain considerable proportions of woody fibre or cellulose. The 
larger the proportion of woody fibre, and the more indurated its 
condition, in articles of food, the less is their practical feeding- 
Talue, 
The tender cellular fibre of well-ripened turnips, mangolds, 
and other root-crops, the cellular fibre of grasses, and the woody 
fibre of the straw of cereal crops, reaped somewhat green, or 
^before the cereal grains have arrived at full maturity, however, 
is digestible by herbivorous animals in a large measure, and 
to a larger extent by horned cattle than by sheep. Conse- 
quently it possesses a certain nutritive value which is greater or 
smaller according to the degree of induration in which it occurs 
in the food. 
Mineral Constituents of Food. — Although the mineral- or ash- 
constituents of food play an important function in the animal 
economy, as explained already, we need not take special account 
of them in considering the comparative nutritive value of the 
various food-constituents, for all our ordinary stock foods contain 
an ample supply of mineral matter to meet the requirements of 
the animal. 
It is worthy of observation, however, that articles of food, such 
as the seeds of leguminous plants, rich in nitrogenous con- 
stituents, and specially well adapted as food for young growing 
