The Oskaloosa herald. (Oskaloosa, Mahaska County, Iowa) 1885-1919, 1907-08-22
LIVE STOCK ON THE Farms
By w. ]. Kennedy, Iowa State College Of Agriculture


digestive juices in the mouth, stom-
ach and intestines have acted upon
the different compounds Of the food,
dissolying out portions to be taken
into the body. there is still portion
of the food which passes on through
and out Of the alimentary canal. This
portion of the food is known as the
feces, or solid excrement. When this
portion Is analysed there are found
in 1t more or less heterogeneous COM
pounds, some carbohydrates in the
form of gums and cellulose, and waste
products of digestion that have come
from the juices and from the walls of
the alimentary canal. The nitrogen
Gus substances found In the feces
vary considerably m amounts, accord
ing to the folders fed. A much larger
percentage of protein is digested
from foods such as oil meal, from
which 81 per cent is digested, than
from coarse folders such as wheat
straw, Of which only % per cent of
the protein Is digested. Timothy has
only As per cent of its protein digest
ed, while pasture grass has IS per
cent. 1t is not definitely known just
why there should be such difference
but 1t seems as ii the amount and
condition of the crude fibre plays an
important part In influencing the di-
gestion of the proteids.
OF the carbohydrates, too, there is
still much to learn. We know, how.
ever, from careful Investigations
made by Jordan and others, some
thing regarding the digestion of these
compounds. Sugar is soluble, and, it
is believed, is all digested and alb
sorbed; starch is changed to sugar by
the digestive juices, and 1t, too, is alb
sorbed. These facts are believed for
two reasons: First, because these
substances have been completely d.
gested by artificial methods; and,
second, because careful investigations
have shown that there were no traces
[of either starch or sugar in the feces
of the animal We conclude from
this that the starches and sugars are
completely digested. Some starches
are much more quickly acted upon
than others. Some require eighty
times as long as others under pre-
cisely the same conditions. Potato
starch is much more readily acted up
on than that contained in the cereal
grains.
Gums and cellulose are still sub
jects of study. OF these substances
oftentimes more than half escapes d.
gestion. Just how they are digested
is not known. 1t may be that they
undergo complete chemical change,
and it may be that their digestion is
the result of fermentation processes.
1t has been ascertained by a careful
investigation of feeding stuffs that on
an average they run from to 16 per
cent gums, of which 46 to n per cent
was digestible. Crude fibre proved
from Sc to so per cent digestible.
The same is true OF fats and oils.
The extent of their digestion and alb
sorption is not definitely known. The
present method of dissolving out the
fats and oils by means of ether does
not give US an accurate knowledge
concerning them, as there are other
substances, too, which dissolve in the
ether and appear in what is called
the ether extract. From the feces the
ether dissolves not only the fats, but
also certain bile salts and other pro-
ducts Of the digestive fluids. BY TAX
ing the difference between the fats in
the food fed and that which appears
in the feces would not give an accur-
ate idea of the amount digested by
the animal. 1t is believed that pure
vegetable fats are quite completely
emulsified and absorbed.
When a feeder knows approximate
ly the composition Of his feed stuffs,
he can estimate pretty closely the
degree of its digestibility. The great
er the amount of starch and sugar
and the less the amount of gums and
crude fibre, the higher the digestibil-
ity OF the feed stuff.
From what has been said so far, the
feeder will come to the conclusion
that he has little to do with the di.
gestion of the animals food; that the
fermentation processes and chemical
changes are wholly dependent upon
fixed physiological laws over which
he has mo control. 1t is true that
these laws prevail. It is also true,
as we see further on, that the feeder
has an important part in making the
conditions such that these laws shall
be efficient in their workings.
Palatabllity.-We all know what is
meant by the expression "my mouth |
waters" Something tasty, something
nicely prepared, something dellcately |
favored, appeals to our nervous sys-