A NOTE ON THE CRUDE FIBRE OF SUNFLOWER (HELIANTHUS
ANNUUS)
By ATAM SINGH, B.Sc. (Agri.), Chemical Research Laboratory, Punjab Agricultural College, Lyallpur
(Received for publication on 2 November 1942)
READ [ 1933] found that sunflower can be grown
throughout the year under the climatic conditions
prevalent in the Punjab and, since it can provide
green fodder throughout the year, he designated
sunflower as 'All the year round fodder crop.'
Lander and Dharmani [ 1936 ] undertook detailed
investigations on the nutritive value of this fodder
by actual feeding trials. They found that it
constituted a maintenance ration for heifers
when fed ad lib.
From the data obtained from digestibility trials,
it was observed that the coefficient of digestibility
of crude fibre of sunflower in comparison with
that of other fodders used by them in their inves-
tigations, was conspicuously low. This is clear
from the following figures reported by them :—
Feed
Sunflower . . . . .
Oat hay . . . . .
Dub grass . . . . .
Wheat bhusa . . . . .
Juar . . . . . .
Average digesti-
bility coefficient
of crude fibre
20.2
66.2
53.8
61.2
57.3
In order to find out the factors responsible for the
low digestibility of crude fibre of sunflower, a
study into the nature and chemical composition
of the crude fibre of all these fodders was under-
taken. The results obtained are presented in this
short note.
The term ' crude fibre ' is applied to that
portion of the organic material which is left
over after the digestion of fat-free material with
dilute acid and alkali. As is well-known, it is
neither a single definite chemical compound
nor a group of definite compounds such as are
proteins, fats and carbohydrates. On the other
hand, it has been shown to consist mainly of
lignin and cellulose, together with a very small
quantity of resistant hemicelluloses. As the
digestibility of crude fibre naturally depends on
that of its constituents, lignin, viz. and cellulose,
it will not be out of place to give a brief account
of the chemical and biological significance of these
constituents.
Lignin. It is believed to occur in plants as
lignocellulose. Glucosan-xylan series are re-
garded as the fore-runners of lignin, but neither
its chemical structure nor the manner of its com-
bination with cellulose is fully understood. In
the alimentary system, it is neither attacked by
digestive enzymes nor by bacteria, and is thus
voided without being utilized by the animal.
Crampton and Maynard [ 1938 ] found out in a
series of feeding trials that more than 95 per cent
of lignin of the feed was recovered in faeces. The
concensus of opinion, therefore, is that lignin is
very slightly metabolizable by the animal.
Cellulose. It forms the principal constituent of
the cell-wall and, on hydrolysis, is converted
into glucose. It is hydrolysable by the enzymes
known as celluláses. These enzymes are widely
distributed in plant tissues. The hydrolysis of
cellulose by the digestive enzymes in the animal
system, however, is of little importance. More-
over Scheunert and Grimmer [ 1906 ] have shown
that the celluláses, which occur in feeds, do not
play any important role in the digestion of cellu-
lose in the animal system. The digestion of
cellulose is affected by the enzymes produced
by the symbiotic micro-organisms which inhabit
the alimentary canal. This process of digestion
of cellulose is best understood in the case of
ruminants where the bacterial
digestion of
cellulose takes place both in the rumen and the
large intestine as shown by Woodman [ 1928 ]
and Woodman and Stewart [ 1932 ].
Estimations of cellulose and lignin contents of
the above feeding stuffs and their crude fibres
were made on dried samples. Methods of analysis
followed were those suggested by Waksman and
Stevens [ 1930 ].
The results of analysis are given in Table I.
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