NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
324 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
If the results of the other components, viz., dry matter, organic matter, ether
extract, and nitrogen free extract (Appendix V) are examined it will be found that
the co-relations are quite high with the observed ratios of variance quite above the
minimum requirements of Fisher's 1 per cent. points of distribution. In these
cases also the observed and expected (i.e., calculated) values of digestion has been
separately plotted out (Charts 8, 10 and 11) to present a visible picture of the
nature of variation. The results by graphical method have been shown in Table IX
and Graphs 2, 3, 6 and 7 and also in Appendix III.
In the graphs the circles of error show the extent of deviation from the mean.
These errors are on the actual values of consumption and digestion (Appendix III,
Columns 4- and 6). Still they are quite small and would have appeared still less had
they been shown in percentages. It should be stated here that although the
graphical method cannot be as accurate as that by the application of regression
equations, yet the agreement between both particularly in the case of roughage
(paddy straw) has been remarkably close (Table 9, Columns 2 and 3 and also
Appendix VII) with respect to all the components including even crude fibre.
With linseed cake also the agreement has been as good for protein and ether
extract, but there has been some variation with dry matter, organic matter and
nitrogen free extract. Yet taking into account the likely extent of variation
inherent with the free hand drawing of the graphical method, the agreement can
be said to be fairly satisfactory for all the individual components with the solitary
exception of crude fibre in linseed cake which has been dealt with, separately.
With regard to graphical analysis (Charts 2—7) it might be stated that despite
its limitations it should form an indispensible adjunct to the regression equation
method, as it serves to throw highly intersting side lights on many aspects. As an
instance it may be noted that the mean consumption under all the three sets of
combination has formed an almost perfect straight line in the case of all the
components. The line showing the digestion has also passed either through or very
close to the mean. Such an occurrence would strongly suggest that the relation is
linear and the subsequent application of multiple regression equations is justifiable.
The small magnitude of errors obtained by the graphical method as well as the
high co-relation values and observed ratios of variances obtained by regression
equations, strongly suggest that the animals behaved normally and the extent
of selective action within the limit of 1 to 3 lb. combinations of cake was not pro-
bably much or appreciable. This method will further enable us to ascertain whether
there is any variation in the digestibility of roughage with the addition of different
concentrates.
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
325
Crude fibre. This component demands special attention. Its digestibility
co-efficient for paddy straw has been quite in agreement by both the graphical
method and regression equation method. But in the case of linseed cake the
graphical method has given 27.3 per cent. as the digestibility, whereas by the
regression equation method the value has been 7.71 per cent.
In the graphical method however it is noted that the errors on mean (Chart 6)
has been generally high particularly for the 2 lb. combination both for digestion and
consumption. The straight line (Chart 6) representing digestion has passed almost
horizontal with the x axis, indicating that with the increasing doses of cake the
proportion of digestion increased very little. These factors have involved a high
error reflecting in a wider variation by the two methods.
It may be stated that the results of crude fibre cannot be considered satisfactory.
On the basis of regression, equations it was the only component in which the
co-relation was so low as 65.51 per cent. and the observed ratio of variance was
below 1 per cent. points of distribution although within 5 per cent. distribution
(Appendix V). As will be noted below (Table X bottom row), the mean fibre
digestion (also indicated by Chart 6) has not been significantly different under
different groups, i.e., from ration to ration. Hence its validity has been of a lower
order.
TABLE X.
Crude fibre in total feed.
Consumed . .
Voided in fæces .
Digested . .
—
1
Paddy straw . .
Linsced cake . .
. .
Total .
. . . . . . .
. . . . . . .
Crude fibre (Mean)
1 lb. group
gm.
2
1311.237
36.967
1348.204
530.365
817.839
2 lb. group
gm.
3
1321.697
73.902
1395.599
582.499
813.100
3 lb. group
gm.
4
1330.002
110.869
1440.871
692.865
838.006
The mean total amount ingested has been in increasing order with increasing
doses of cake in the case of all the components including crude fibre (Appendix V)
but while all the others have shown more or less an increasing amount of total
D
326 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
digestion, the digestion of this component has been practically stationary and
possibly even lower. At any rate the figures under the 2 lb. combination would
rather indicate a tendency of decreasing digestion ; and if they are compared with
the figures of 1 lb. combination it will be seen (Table XI)
TABLE XI.
——
1
2 lb. combination (a) . .
1 lb. combination (b) . .
Difference (a—b) . .
Crude fibre consumed
From straw
gm.
2
1321.7
1311.2
10.5
From cake
gm.
3
73.9
37.0
36.9
Total
gm.
4
1395.6
1348.2
47.4
Voided in
fæces
gm.
5
582.5
530.4
52.1
Digested
gm.
6
813.1
817.8
—4.7
that on the basis of difference between 2 lb. and 1 lb. combinations the increase in
consumption of fibre was 47.4 gms., whereas the corresponding amount voided in
the fæces was 52.1 gm., i.e., more than what was ingested. Thus there was a
negative digestion of—4 . 7 gms. This difference is no doubt small, nor is it intended
to be treated in the statistical sense ; yet there appears to be some justification in
referring to it, as this aspect taken with other factors has a bearing on a highly
interesting side issue.
The behaviour of crude fibre seems to suggest that during the process of diges-
tion some special phenomenon intervenes which reacts in such a way on the food
material as to effect an apparent increase in the fibre fraction of fæces or undigested
residue, thereby showing an apparent decrease in the digestion. That such a
probability is not unlikely seems to be borne out by the exceedingly interesting
work of Woodman and Stewart of Cambridge [1932].
The fibre digestion of ruminants takes place by bacterial agency in the stomach,
and these two authors have found by incubating linseed and other oil cakes with
bacterial cultures that the ether soluble fraction of the oil cakes appears to produce
some organic substance which is able "to resist solution by the reagents
employed for the estimation of fibre". In consequence of this the amount of
what is estimated as fibre is naturally increased in the undigested residue
sometimes even more than what originally was present in the cake. In the
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
327
experiment by the above authors this increase has been such as to yield a negative
value, viz.,—101.1 per cent. (in one case). These values have been termed by the
above authors as " fermentation co-efficient " corresponding to the digestible co-
efficient of feeds. Our results also strongly suggest the probability of similar
occurrence ; and the rather divergent values of the digestibility co-efficients of crude
fibre in linseed cake given by European and American authors might possibly be due
to this hitherto unnoticed cause. Henry and Morrision [1928] have given the
American value to be 57 per cent. and the same value of Kellner [1926] is 32 per
cent. Not only is there a wide difference between these two values but
according to Kellner the value oscillates between 0 per cent. to 92 per cent. Such a
difference is suggestive of some phenomenon outside the normal course possibly of
the nature indicated by Woodman and Stewarts' experiments. Armsby's statement
[1930] also indicates that in a mixed ration of roughage and concentrate the value
of crude fibre (and also ether extract) is much affected when the proportion is wide.
But this statement following after a reference to meadow hay and maize meal does not
seem to refer to oil cake and as such may not be quite applicable in the circumstances
of this case ; but the difficulties arising in his case are the main reason to cite it, for
he states that " In extreme cases, absurd results are sometimes obtained such as
negative digestibility or a digestibility greater than 100 per cent." In this experi-
ment, the results shown in Table XI are also indicative of the tendency towards
negative digestion and the very low value (7.71 per cent.) obtained by the regression
equation (being based on the results of 18 tests) might possibly be explained by the
probability that the individual digestions ranged between both negative and positive
figures in a somewhat similar way as might possibly be the underlying cause for the
values of 0 per cent. to 92 per cent. found by Kellner.
The chief causative factor for it is probably associated with the findings of
Woodman and Stewart already noted. It might be stated here parenthetically that
changes of a like nature were also apprehended by Armsby [1910], for he states
" We have to take account of the possibility of conversion of members of one group
of nutrients into those of another. For example, it seems not improbable that a
portion of the crude fibre of feeding stuffs may be so modified in the digestive
tract, without being actually dissolved, that in the fæces, it is determined as
nitrogen free extract, thus diminishing the apparent digestibility of the latter group
or increasing that of the crude fibre."
Such a phenomenon, whether like that suspected by Armsby or this, would stand
in the way of accurate determination by any method not to speak of the one forming
the basis of this paper. The matter is however under investigation. Leaving
therefore this solitary exception of crude fibre, the results worked out by the new
method have in all other cases conformed fully to the requirement of statistical test.
D 2
328 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
CONCLUSION.
In digestion experiments the first condition, whether with one or more feeds,
must be that the ration should on no account fall below a balanced supply. Given
this condition, the next step is to calculate the digestibility from the amount
consumed and the portion voided.
In a single feed the calculation is simple unless the feed is deficient like paddy
straw, when complications arise on account of irregular digestion,
In a mixture of more than one feed the computation based on what has been
termed as " method of elimination " might affect the resulting values according as
the assumed standards differ from the actual; and hence the use of such (outside)
standards (based on conditions different from ours) might often be inapplicable as
occurred in this case ; but even when they are applicable they require to be verified,
and above all local data under local condition are always preferable.
These considerations led the authors to try out other methods ; and the experi-
mental design and graphical method of analysis were the outcome of same. As a
counterpart of the graphical method, multiple regression equations were subsequently
tried and adopted. The chief advantage of both these methods are that they enable
direct calculation to be done without having recourse to the doubtful alternative of
using assumed values for a part of the feed.
To provide suitable data for calculation by these methods the experiment should
be so designed as to ensure a reasonable number of tests in which all the animals
selected should at one time or other, be under all the different doses intended for the
investigation. The scheme undertaken by the authors with six animals was on a
restricted randomised basis with 1 lb., 2 lb. and 3 lb. linseed cake; and was so
designed as to enable eighteen individual tests in all, in which all the six animals
in pairs or groups of two, were at one time or other under all the three combina-
tions. This enabled uniform distribution of feed as well as all the animals, over the
entire span of the experiment and also helped in the elimination of the largest
possible avoidable errors. The design can be improved further, say, with more
animals giving more groups.
The initial figures thus obtained from the experiments can then be used for the
direct calculation of digestibilities either by the graphical method or by multiple
regression equations, or both.
The results obtained by the authors have been quite encouraging, having
conformed to the requirement of statistical tests in the case of all the components if
we exclude the notable exception of crude fibre, since in this case extraneous causes
appear to have intervened.
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
329
If this method stands up to subsequent trial, as it is confidently expected that
it will, then the computation by its aid will remove a long felt difficulty.
The advantages of the method might be summed up as follows :—
1. Direct estimation of individual digestibilities in a mixture of more than
one feed.
2. Dispensing with the present unavoidable alternative of using assumed
values.
3. Study of same roughage under different concentrates and different
roughages under same concentrates thereby enabling the determination
of variability, if any, under these varying factors.
SUMMARY.
1. A resume has been given showing the difficulties associated with the
prevailing methods of calculating digestibilities in a single feed or in a mixture of
more than one feed. The uncertain nature of the results when the feed is deficient
in any one constituent has been emphasised.
2. The design of the experiment, as undertaken by the authors on a restricted
randomised basis, has been shown with 1 lb., 2 lb. and 3 lb. combinations of linseed
cake and paddy straw. The design can be further improved upon by a larger
number of animals and tests.
3. The results with assumed digestibilities on the basis of outside standards
have been worked out and discussed, showing their unsuitability of application in
many cases as was also experienced by Woods and Eckles.
4. The need of verification of outside standards and preference of local standards
for local feeds have both been emphasised.
5. The graphical method and process of working have been described and the
graphs for each component have been shown in separate charts with the circles of
error, and the digestibilities computed.
6. The multiple regression equations method following as a corollary to the
graphical method has been described and the process of calculation shown
(Appendix IV).
330 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
7. Both graphical method and regression equation method enable direct
calculation of digestibilities in a mixture of more than one feed and both have shown
a reasonable order of agreement.
8. The digestibility of crude fibre with respect to linseed cake has been found
to be the only instance which has shown discrepancy, but the cause of it appears to
be associated with some bacterial action as indicated by the findings of Woodman
and Stewart [1932].
9. The chief advantages of both the methods are:—
(a) they enable direct calculation in a mixture of more than one feed.
(b) different roughage and concentrates can be separately worked out to
study their behaviour on each other under various combinations and
proportions.
ACKNOWLEDGMENTS.
Our first acknowledgment is due to the Imperial Council of Agricultural
Research, India, for providing the grant to conduct the investigations.
Our thanks are due to Mr. F. J. Gossip, Live-stock Expert, Bengal, for stall
facilities and many practical suggestions.
We acknowledge our indebtedness to Professor Mahalanobis and his able
colleague Mr. S. Bose of the Indian Statistical Institute, Calcutta, for the helpful
suggestions with statistical analysis and unfailing courtsey they extended to us in
connection with the work.
We record our thanks to Mr. S. M. Patwari, for a part of chemical analysis, to
Munshi Shamsul Haque for conducting the feeding trials and also to Messrs.
Birendranath Shome and Sachindra Nath Banerjee for the preparation of charts.
REFERENCES.
Armsby, H. P. (1910). The Principles of Animal Nutrition (3rd Edition).
—
(1930). The Nutrition of Farm Animals 1917.
Brunt. Combination of Observation.
Eckles, C. H. (
). Mo, Res. Bul. 7.
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
331
Fisher, R. A. (1925). Statistical methods for Research workers.
Henry, W. A., and Morrison, F. B. (1928). Feeds and Feeding (19th Edition).
Kellner, O. (1926). The Scientific Feeding of Animals translated by Goodwin W. (2nd Edition revised).
Lander, P. E., and Dharmani, L. C. (1931). Ind. Jr. Vet. Sc. and Anim. Husb., I, 177-191.
Mahalanobis, P C. (1932). Ind. Jr. Agr. Sc., 2, 679-693.
Warth, F. S. (1923). Agr. Jr. India, 18, 456-464.
—(1926).
Memoir Dept. Agr. India, Chem. Series, 9, 2.
—(1929).
Annual Report of the Imperial Physiological Chemist, 1928-29.
—and
Gossip, F. S. (1928). Memoir Dept. Agr. India, Chem. Series, 10, 1.
Wood, T. B., and Yule, G. U. (1914). Jr. Agr. Sc., 6, 248.
Woodman, H. E., and Stewart, J. (1932). Jr. Agr. Sc., 22, 3, 527-547.
332 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
APPENDIX I.
Aman paddy straw and 1 lb., 2 lb. and 3 lb. linseed cake. Nitrogen balance and
live-weights (loss or gain).
Animal No.
1
D 1 .
.
.
D 2 .
. .
D 3 .
.
.
D 6 .
.
.
D 7 . . .
D 8 .
.
.
1 lb. combination.
Nitrogen
balance
grms.
2
+0.966
+1.572
+4.804
+2.415
+3.262
+0.369
Loss or gain
in live-
weight
lbs.
3
—0.28
—1.54
+0.64
+ 0.41
+0.43
+0.31
2 lb. combination.
Nitrogen
balance
grms.
4
+10.309
+8.325
+2.980
+4.421
+8.261
+4.519
Loss or gain
in live-
weight
lbs.
5
+1.20
+0.95
+0.31
+0.48
+0.71
+0.58
3 lb. combination.
Nitrogen
balance
grms.
6
+9.466
+6.255
+9.147
+9.240
+ 15.740
+14.441
Loss or gain
in live-
weight
lbs.
7
+ 1.300
+0.880
+0.910
+0.990
+1.230
+1.570
APPENDIX II.
Digestible nutrients etc., received by each animal. (Paddy straw and 1 lb., 2 lb.
and 3 lb. linseed cake).
Animal
No.
D 1 .
.
D 2 . .
D 3 .
.
D 6 .
.
D 7 .
.
D 8 .
.
1 lb. group.
Total
digesti-
ble
nutrients
lbs.
4.480
5.005
4.866
4.386
4.047
4.016
Nutritive
ratio
1:
16.004
17.541
15.410
14.018
13.649
16.179
Net
energy
(Therms).
2.971
2.980
3.059
3.004
2.742
2.818
2 lb. group.
Total
digesti-
ble
nutrients
lbs.
5.445
5.325
4.929
4.420
5.051
4.984
Nutritive
ratio
1:
8.971
9.310
8.753
7.464
9.671
10.010
Net
energy
(Therms).
3.840
3.728
3.612
3.669
3.999
3.489
3 lb. group.
Total
digesti-
ble
nutrients
lbs.
5.442
5.728
5.868
5.442
5.619
5.683
Nutritive
ratio
1:
6.090
6.835
7.128
6.348
6.173
6.457
Net
energy
(Therms).
4.423
4.440
4.218
4.149
4.279
4.340
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
333
APPENDIX III.
Data used for graphical methods (see graphs).
Components
Dry matter . . {
Organic matter . {
Crude protein . {
Ether extract . {
Crude fibre . {
Nitrogen-free ex {
tract.
Group
0 lb.
1 „
2 „
3 „
0 lb.
1 „
2 „
3 „
0 lb.
1 „
2 „
3 „
0 lb.
1 „
2
3 „
0 lb.
1 „
2 „
3 „
0 lb.
1 „
2 „
3 „
Consumed
from
linseed
cake
grms.
0.0
400.0
800.0
1200.0
0.0
367.3
734.3
1101.5
0.0
128.3
256.5
384.7
0.0
35.43
70.82
106.25
0.0
37.0
74.0
111.0
0.0
166.6
333.3
499.7
Total consumed from
paddy straw and
linseed cake
Mean
grms.
(2862.0)*
4294.0
4736.0
5163.0
(3326)*
3719.6
4117.3
4509.3
(147.0)*
276.86
406.13
535.74
(45.0)*
80.88
116.56
152.35
(1302.0)*
1348.2
1395.6
1440.9
(1830.0)*
2013.65
2202.02
2380.36
Error on
mean
grms.
..
99.29
99.46
40.44
...
80.99
79.17
32.48
...
4.13
7.76
6.83
...
0.83
0.89
1.19
...
34.66
59.28
11.61
...
43.43
46.44
19.05
Total digested
Mean
grms.
(1751.0)*
2044.0
2286.0
2605.0
(1687.0)*
1963.2
2195.6
2493.3
(13.0)*
123.48
226.62
340.96
(19.5)*
53.71
87.46
121.90
(803.0)*
817.84
813.10
838.01
(845.0)*
968.21
1046.93
1192.44
Error on
mean
grms.
...
78.94
49.77
24.96
74.32
46.15
26.63
...
4.19
5.40
8.74
...
1.40
1.37
1.74
...
36.04
87.30
64.19
...
36.61
37.65
10.76
* The figures in brackets have been directly read from the graphs.
334 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, IV.
APPENDIX IV.
Detailed Calculations by the aid of Multiple Regression Equations.
The experiment was conducted with two unknowns, viz., paddy straw and
linseed cake in three combinations, viz., 1 lb., 2 lb. and 3 lb., doses of cake.
There is no direct way by which we can establish whether there is any or no in
teraction taking place during the course of digestion with these two feeds. The same
statement holds good for the progressive doses of cake as used in our experiment.
The results worked out by the graphical method suggested that within the range of
1 lb., 2 lb., and 3 lb. combinations the inter-action at any rate is inappreciable.
We may therefore neglect it for the purpose of our experiment, and as a first ap
proximation, assume that the behaviour of cake and straw with respect to their
individual digestibilities is independent of each other and also constant. The
subsequent analysis of the results, as will be evident from the details in the text,
also shows that this assumption is justifiable within the limits of sampling error in
the case of the majority of the individual components of both the feeds.
Considering first the digestibilities of, say, crude protein (nitrogen) if x 1 and x 2
are the amounts consumed from straw and cake respectively, and if a and b re
present the digestible fractions of x 1 and x 2 respectively, we obtain the linear rela
tion
y = x 1 + x 2 b
*
.
.
. (1)
where y = the observed amount of total digestion from straw and cake.
If the equation gives a good fit, it should reasonably follow that the hypothesis
holds good ; and that the values of a and b thus obtained represent the nearest
approach to the fractions actually digested from the respective shares of x 1 and x 2 .
In order that equation (1) can be made solvable by ordinary algebric process
Gauss's method is employed whereby the following equations are obtained:
ε x 1 y = a ε x 1
2 + b ε x 1 x 2 .
.
.
. (2)
ε x 2 y = a ε x 1 x 2 + b ε x 2
2
.
.
.
. (3)
* Since when x 1 — 0 and x 2 = 0 the amount digested is necessarily zero, therefore no constant
has been added. From the observed values also, the value of c is found to be negligible in all cases.
DETERMINATION OF DIGESTIBILITY CO-EFFICIENTS
335
Taking the case of protein (nitrogen), the summations of eighteen individual values of x 1 y, x 2 y, x 1 x 2, x 1
2 , x 2
2
etc., are worked out as follows :—
—
1 lb. cake . .
2 lb. cake . .
3 lb. cake . .
Bullocks
D 1
D 2
D 3
D 6
D 7
D 8
D 1
D 2
D 3
D 6
D 7
D 8
D 1
D 2
D 3
D 6
D 7
D 8
Total .
Actually
consumed
Paddy
straw
x 1
24.19
24.42
25.25
25.32
22.14
21.31
26.80
25.27
22.96
24.11
21.61
22.94
24.78
24.00
23.76
23.34
24.15
24.94
...
Linseed
cake
x 2
19.60
19.60
20.96
20.96
21.02
21.02
41.91
41.91
42.03
42.03
39.15
39.15
63.05
63.05
58.75
58.75
62.87
62.87
Total
amount
actually
digested
y.
19.14
19.61
21.53
21.21
20.08
16.98
38.09
37.50
36.70
37.93
34.38
32.95
55.75
53.09
52.44
53.78
56.90
55.35
663.41
x 1 x 2
474.12
478.63
529.24
530.71
465.38
448.15
1123.19
1059.07
965.01
1013.34
846.03
898.10
1562.38
1513.20
1395.90
1371.23
1518.31
1567.98
17759.97
x 1 y
463.00
478.88
543.63
537.04
444.57
361.84
1020.81
947.63
842.63
914.49
742.95
755.87
1381.49
1274.16
1245.97
1255.23
1374.14
1380.43
15964.76
x 2 y
375.14
384.36
451.27
444.56
422.08
356.92
1596.35
1571.63
1542.50
1594.20
1345.98
1289.99
3515.04
: 347.32
3080.85
3159.58
3577.30
3479.85
31534.92
x 1
2
585.16
596.34
637.56
641.10
490.18
454.54
718.24
638.57
527.16
581.29
466.99
526.24
614.05
576.00
564.54
544.76
583.22
622.00
10367.94
x 2
2
384.16
384.16
439.32
439.32
441.84
441.84
1756.45
1756.45
1766.52
1766.52
1532.72
1532.72
3975.30
3975.30
3451.56
3451.56
3952.64
3952.64
35401.02
y 2
366.34
384.55
463.54
449.86
403.21
288.32
1450.85
1406.25
1346.89
1438.68
1179.24
1085.70
3108.06
2818.55
2749.95
2892.29
3237.61
3063.62
28133.51