256
Nutritive Values of Different Parts of Napier Grass
[XVII
If the distribution of nitrogen and dry matter between leaves and stems is examined, by far
the largest amount of nitrogen, whether in terms of total yield or percentage, falls to the share of
leaves. The converse is the case with the dry matter. In this the stem accounts for the largest
share with the lowest percentage and total yield of nitrogen. Another interesting feature is that
up to the 5 ft stage the yield of dry matter of the leaves does not seem to exhibit significant variation.
The drop at 6 ft. is largely because of slower growth during the dry season. The results suggest
that the outturn of leaves (dry weight) does not undergo precipitous variation. There is no doubt
some fall in the outturn of nitrogen (in leaves) per unit area. The main variation is with the stem
which increases its dry matter as it increases in height but at the same time it translocates its nitrogen
to the leaves and shows a decreasing amount in the percentage or yield.
Since the criterion of digestibility and assimilability is closely connected with the coarseness
and quantity of dry matter specially from the stem, it would seem that growth above 3 ft. (or at the
most 4 ft.) is likely to react adversely against economic utilization. Only a limited amount of
analysis of the organic components of the composite samples of 1932 crop was conducted and the
results are setforth in Table III.
TABLE III
Composition of Napier grass of different heights (dry basis)
Components
Crude protein . .
True protein . . .
Ether extract . .
Crude fibre . . .
Nitrogen-free extract .
Ash
.
.
.
.
Soluble ash . . .
Silica .
.
.
.
Chlorine (estimated from
ash)
Leaves
1 ft.
Per cent
14.8
12.5
2.4
21.8
44.0
17.1
9.3
7.8
0.1
2 ft.
Per cent
8.4
6.3
2.6
26.4
49.9
12.7
7.5
5.2
0.2
3 ft.
Per cent
8.8
6.7
3.4
30.1
45.6
12.1
7.0
5.1
0.3
4 ft.
Per cent
7.2
5.7
3.2
30.7
48.2
10.8
7.0
3.8
0.2
5 ft.
Per cent
6.5
4.3
2.3
30.7
48.8
11.8
..
..
..
6 ft.
Per cent
8.1
7.3
2.5
31.3
47.2
11.1
5.8
5.3
..
Stem
1 ft.
Per cent
10.7
6.8
2.2
28.9
41.9
16.4
12.8
3.6
0.7
2 ft.
Per cent
6.9
4.9
14
26.7
51.7
13.4
11.0
2.4
0.6
3 ft.
Per cent
6.5
4.4
1.9
29.4
47.4
14.8
11.9
2.9
0.6
4 ft.
Per cent
5.3
4.4
1.8
28.8
51.0
13.2
11.8
1.4
0.6
5 ft.
Percent
3.8
2.3
1.0
33.1
49.8
12.4
10.4
2.3
0.6
6 ft.
Per cent
2.7
2.2
0.9
32.9
54.1
0.4
7.5
1.9
..
The main feature here is a higher percentage of protein in the 1 ft. stage which can be detected
in Figs. 1 and 2 also. From the 2 ft. stage the protein content in the leaves remains about the same
but in its stem it has gone down. As can be expected the ether extract percentage is more in the
leaves than in the stems. With respect to fibre the lowest percentage (21.78 per cent) has been
recorded for leaves at the 1 ft. stage, and to some extent upto the 2 ft. stage, but above heights they
are about the same. As a matter of fact from the 3 ft. stage the percentage of crude fibre whether in
leaves or stems is about the same. At the same time the fibre fraction of the leaves is likely to be
better digested than that of the stem.
The main feature of the ash content is that the stem has more soluble matter and corresponding-
ly less acid insoluble residue than the leaves. This aspect will be taken up again later.
VARIATION IN THE NUTRITVE MAKE-UP OF THE SOFTER AND THE COARSER PAR
It will be noted from a general survey of the preceding that possibly somewhere about the 3
to 4 ft. stage the combinations of components are such as to provide an economic utilization. An
experiment conducted in 1941 suggests this in a more impressive manner. The indications were
obtained in the following way. During the course of feeding amon straw and Napier grass it was
noticed that the animals often left an appreciable fraction of the harder part of the stem. It was