NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
184
Wool Quality as the Basis of Individual Selection
waves or the crimps just disappeared. The method of tabbing was also fol-
lowed here. The same number mentioned above for fineness determination
was recorded for length measurement.
The fibres termed ' heterotypes' in this work are the partially medullated
fibres in the fleeces. The weights of these denote the percentage of medullated
fibres in that sample, and not medullation percentage which actually shows
the total medullation value of a particular sample. The medullation per-
centage can correctly be measured by the Medullometer devised by McMahon
at the Massy Agricultural College, New Zealand. The study was restricted
to recording the percentage of medullated fibres.
These fibres after being classed by hand were tested both by the Elphic
Benzol method and by keeping a careful scrutiny when spread for measure-
ment of diameter under the microscope.
CLASSIFICATION OF SUBJECTS
1. Study of types of fibres.
2. Study of the total population of fibres irrespective of types.
3. Determination of minimum number of tests for obtaining a reliable
mean for measurements of diameter and length for each type of fibre.
4. The quality of wool on different zones.
5. Analysis of variance.
6. Method of recording individual and progeny performances.
7. Miscellaneous notes in the study of wool quality.
1. Study of types of fibres
There are four types of fibres in the fleece of 'A' grade Deccan sheep, viz.
(1) fine fibres, (2) strong fibres, (3) heterotypes and (4) kemps.
Fine fibres.—This term has been used because these fibres can be classed
with the fine wools like those of the Merino. These are extremely pliable and
give a downy feel. They are covered with fine serrated scales and are dis-
tinctly crimpy with approximately ten crimps per inch, but the crimps are un-
even. An increase of the fine fibres in the fleece will give it the felting quality
which the average Deccani wool lacks. The study of monthly growth of fleece
has shown that this fibre can grow continuously. It has a more even staple
than the other fibres. Length measurements were taken from region to
region. These results are consolidated in Table I according to regions.
The. average length based on 6,000 readings is 2.28 in. for a six-monthly
growth, the standard deviation being 0.483 with the coefficient of variation of
E.
J.
BRUEN
185
TABLE I
Table of constants for length measurements
Samples
Neck
Wither
Shoulder
Side
Back
Britch
Fine fibres
Mean
2.41
2.56
2.11
2.29
2.28
2.00
S. D.
0.0156
0.0155
0.0136
0.0113
0.0141
0.0137
C. V.
20.42
19.18
20.38
15.92
19.56
21.65
No.
1,000
1,000
1,000
999
1,000
1,000
Strong fibres
Mean
3.45
3.57
2.81
3.10
2.46
2.74
S. D.
0.0228
0.0211
0.0228
0.0237
0.0153
0.0234
C. V.
20.95
18.63
21.42
20.38
18.59
25.62
No.
1,000
1,000
700
730
890
900
Heterotypes
Mean
2.84
3.05
2.48
2.55
2.15
2.51
S. D.
0.0209
0.0214
0.0222
0.0237
0.0155
0.0224
C. V.
22.04
21.24
23.07
22.36
19.13
23.58
No.
898
954
660
630
700
700
Kemps
Mean
1.21
1.95
1.67
1.69
1.74
1.84
S. D.
0.0311
0.0287
0.0237
0.0254
0.0233
0.0327
C. V.
25.65
24.20
30.54
25.28
23.60
30.65
No.
230
270
450
284
340
305
186
Wool Quality as the Basis of Individual Selection
21.18 per cent. Fig. 1 shows the characteristic graph of these fibres very
clearly.
Fig. 1. Length frequency
The variation in length from region to region is from 2.0-2.56 in. The
maximum length is seen in the wither wool and minimum in that of britch
(Fig. 5).
The mean diameter of these fibres for 6,000 readings is 25.30µ, the stan-
dard deviation comes to 5.32 µ with a coefficient of variation of 21.00 per cent.
The table of constants for diameter measurements is given in Table II. The
readings for diameter of this fibre will be seen to vary from 24.90-26.77µ.
This shows that this fibre is extremely even in its diameter. It can be defi-
nitely said that in the Deccan wool this is the most even fibre both for length
and diameter (Fig. 2).
E. J. BRUEN 187
Fig. 2. Diameter frequency
Strong fibres.—The term 'strong' is used in wool-classing whenever the fibres
have good textile strength and in a class of fleeces a strong wool type generally
denotes a fleece having fibres of comparatively larger diameter. This adjective
has been purposely affixed here because these are the dominant fibres in the
' A ' grade fleece of the Deccan sheep. These fibres give the characteristic
strength and quality to the wool as a class by itself. As stated above the
fine fibres render a felting quality while the strong wool gives the ' character '
and strength to the fleece of these sheep. It is pliable and wavy with
approximately two waves per inch.
188
Wool Quality as the Basis of Individual Selection
TABLE II
Table of constants for diameter
measurements
Samples
Neck
Wither
Shoulder
Side
Back
Britch
Pine fibres
Mean
25.415
24.90
25.15
25.03
26.08
26.77
S.D.
0.153
0.1655
0.1655
0.1538
0.168
0.1746
C. V.
19.0
21.02
20.0
19.44
20.34
20.62
No.
1,000
1,000
1,000
1,000
998
1,000
Strong fibres
Mean
47.25
51.31
51.58
47.20
50.79
49.53
S. D.
0.2413
0.2796
0.3605
0.3370
0.3640
0.2795
C. V.
16.14
16.84
18.49
19.16
20.86
17.71
No.
1,000
1,000
699
720
850
899
Heterotypes
Mean
56.16
59.44
51.94
57.10
61.96
59.76
S. D.
0.4224
0.4015
0.4541
0.5346
0.5332
0.4677
C. V.
22.08
20.29
22.44
23.17
22.19
20.60
No.
862
902
657
611
665
693
Kemps
Mean
68.28
65 .86
59.47
68.42
70.29
68.27
S. D.
0.8011
0.6692
0.5384
0.6692
0.6861
0.6455
C. V.
20.32
19.90
22.18
20.21
20.57
18.95
No.
300
327
600
403
443
402
190
Wool Quality as the Basis of Individual Selection
it starts with a thickness of 52-61µ and in its straight growth broadens up
to 80-104µ. Then it takes a spiral growth having a breadth of 90-114µ
and at the tip it turns suddenly into a non-medullated structure of a fine-
ness of 7µ. But in ' A ' grade sheep kemp takes a less severe structure. It
starts at the proximal end with a diameter of 49.76µ and continues with about
the same breadth for three-fourths of the length and begins its pointed tip
which ends in 5.2µ. The various types can very well be compared by refer-
ring to Plate XVI. In these sheep they have lost the chalky appearance and
have developed a flinty translucency. The measurements of 2,300 kemps
for length are worked out in frequencies. The mean length works to 1.82 in.
with a standard deviation of 00.50 and a coefficient of variation of 27.52
per cent.
The diameter measurements although not a very important factor, were
recorded for 2,300 fibres to understand what type of kemp exists in these sheep.
The mean diameter comes to 66.30µ with a standard deviation of 14.14 and
a coefficient of variation of 28.30 per cent. The curve in Fig. 2 will show the
variation in the population of these kemps.
Medullated fibres.—Peculiar fibres of the type of a degenerate hair were
seen in three ewes Nos. 7, 69 and 5. These fibres grow straight like hair,
have a shining appearance with slight medullation. The epithelial scales are
broad, rounded and are more like those of hair than those of wool. They seem
to be some middle stage between strong wool and hair. They are extremely
even in diameter and lack the waviness and pliability of the true strong wool
described above.
In these ewes, it was found that the fine wool and these fibres dominated
in the fleeces (Table X). It is not possible to lay down whether such sheep are
a type by themselves unless a large flock of ' A ' grade is studied.
2. Study of the total population of fibres irrespective of types
This has been dealt with here finally on the fibre study because each of
the types mentioned above is a separate entity. The reason for classing and
treating each type of fibre independently for length and diameter measure-
ments is very well illustrated by Figs. 3 and 4, one showing the frequencies
for length and the other those for diameter. The heterogeneity of the popu¬
ation is evident from these graphs.
3. Determination of minimum number of tests for obtaining a reliable mean for
measurements of diameter and lengthfor each type of fibre
In every research which requires measurements of a population for a study
of a type or types, it is now a known fact that the most essential work needed
Ind. J. Vet. Sci. & Anim. Husb. Vol. XI, Part III
]
PLATE
XVI
FIG. 1. Types of fibres in ' A ' grade Deccan sheep. The hairy fibres which go to make
the bulk of the ' B & C ' grade are absent in these sheep
FIG. 2. Types of fibres in ' C ' grade Deccan sheep for comparison
PLATE XVII
[ Ind. J. Vet. Sci. & Anim. Husb. Vol. XI, Part III
FIG. 1. Monthly samples of the shoulder wool—' A ' grade Deccan sheep (non-breaking)
FIG. 2. Monthly samples of shoulder wool—' C ' grade Deccan sheep (breaking type)
E. J. BRUEN 191
Fig. 3. Length frequency of the total population (irrespective of types of fibres).
at the outset is to calculate the minimum number of counts which should be
recorded in obtaining a reliable mean for that population. This is ordinarily
calculated after recording readings of a fairly large number and finding out
the standard deviations along with the coefficients of variation. The minimum
192
Wool Quality as the Basis of Individual Selection
Fig. 4. Diameter frequency of the total population (irrespective of types of fibres).
number of tests is then calculated for each type according to the following
formula:—
N=m 2 σ 2 /x 2 Where—
N is the number of tests ;
x is the desired accuracy expressed as percentage of mean ;
σ is the percentage standard deviation (coefficient of variation) ; and
m is the factor for obtaining specific odds.
Thus for odds of 19 : 1 m=1.96 and for 99 : 1 odds its value is 2.58.
E. J. BRUEN 193
In the present study a hundred readings for diameter and length are
carried out for each type of fibre in every zone. Thus the total number of
fine fibres measured amounts to 6,000, and that of the strong fibres to 5,200
and lastly 4,500 for the heterotypes. The coefficients of variation for each
type of fibres are recorded in Tables I and II.
Minimum number of tests.—For both the length and diameter measure
ments over a population of 6,000, the coefficient of variation comes to 20.00
per cent in the case of fine fibres, it comes to 25.00 per cent for length measure
ment and 20.00 per cent for that of diameter in strong fibres. In heterotypes
it averages to 23.00 per cent for both the fineness and length measurements.
With these values for σ the above formula has been applied and the values
of N for different percentages of accuracy for P=0.05 and for P=0.01
are recorded in Tables III-VI.
TABLE III
Number of tests of length and fineness for specified accuracy (fine fibres)
Value of X for P =0.05
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
6146
1537
682.9
384.2
246.0
170.8
125.4
96.01
75.90
61.46
50.79
Value of X for P
= 0.01
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
10640
2662
1183
665.6
426. 0
295.8
217.3
166.3
131.4
106.4
87.98
194
Wool Quality as the Basis of Individual Selection
TABLE IV
Number of tests of length for specified accuracy (strong fibres)
Value of X for P= 0.05
0.5
10
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
9603
2401
1067
600.3
384.2
266.8
196.0
150.1
118.5
96.03
79.36
Value of X for P
= 0.01
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
16630
4159
1848
1040
665.6
462.2
339.4
259.9
205.4
166.3
137.5
TABLE V
Number of tests of fineness for specified accuracy (strong fibres)
Value of X for P= 0.05
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
6145
1537
682.9
384. 2
246.0
170.8
125.4
96.0
75.90
61.46
50.79
Value of X for P
= 0.01
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
10640
2662
1183
665.6
426.0
295.8
217.3
166.3
131.4
106.4
87.98
E. J. BRUEN 195
TABLE VI
Number of tests of length and fineness for specified accuracy (heterotypes)
Value of X for P= 0.05
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
8128
2032
903.3
508.2
326.2
225.8
165.9
126.8
100.3
81.28
67.17
Value of X for P
= 0.01
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No. of tests
N
14080
3521
1564
880.2
563.3
391.2
287.4
220.0
173.9
140.8
116.3
From the results it is evident that in the case of fine fibres the present
experiment is correct to 4 per cent accuracy on either side of the mean for
P=0.05. The accuracy works out to 5 per cent in the strong fibres for length
and 4 per cent fineness for P=0.05. In the case of the heterotype the ex-
periment is correct to 4.5 per cent accuracy for P=0.05 for fineness and length
measurement as well. Hence the fleece analysis carried out in the present
study can be said to give reliable accuracy of 5 per cent for P—0.05 in cal-
culating the mean for diameter and length measurements by taking a
hundred tests for each type of fibre.
Is there a short-cut for quick analysis of the fleeces of Deccan sheep?—One
may think that the method followed above in the classification of fibres by
recording the detailed measurements is going to be a tedious process, when a
large number of sheep are to be studied. The McMahon ' Medullometer '
(1934) when used by trained persons will be able to deal with thousands of
samples in a short time. The quality of each fleece can then be measured
irrespective of classification of fibres by preparing a composite sample
from all the zones. From these again a representative sample can be prepar-
ed and measured for all the attributes of wool which go to form the quality.
Supposing the ' A' grade sheep are a fixed type, it will then be seen that
in the case of diameter measurements, 390 readings and 205 for those of
length will give an accuracy of 5 per cent on either side of the mean for
P=0.05 to obtain reliable means.
196
Wool Quality as the Basis of Individual Selection
4. Quality of wool on different zones
In improvement of sheep for wool bearing character uniformity of
quality is of the highest importance. As explained previously, there is a
great variation in quality from fleece to fleece in the Deccan sheep. The
present study is of the ' A ' grade Deccan sheep selected to carry a fleece
having no hairy fibre. In the breeding of such animals one must go a step
further and find out the variation of wool quality on different parts of the
body. The drive in selection should be towards a sheep having uniform
superior wool all throughout the fleece. This can only be achieved by
regional studies and recording these observations for each generation for
selecting the stud stock. The principal attributes of wool which should be
given importance in judging the uniformity for the Deccan fleeces at this stage
should be medullation percentage, length, fineness, and percentage of kemp.
Out of these, the medullation percentage and uniformity in length are of
primary importance. The fineness of fibres and the percentage of kemp are
to guide the final selection. For the ten ewes under study the details of the
types of fibres are already given. At the same time proportions of each of
these on different zones has been completely worked out. These results are
consolidated in Table VII.
TABLE VII
Percentage of different types of fibres on different regions
Regions
Neck
Wither
Shoulder
Side
Back
Britch
Fine
fibres
24.32
33.52
22.56
27.59
36.57
17.41
Strong
fibres
56.49
44.85
62.97
40.00
31.75
42.12
Medullated
fibres
19.17
(3.56)
22.35
(4.59)
12.37
(4.25)
32.38
(12.52)
31.66
(9.26)
40.45
(8.98)
Remarks
The
figures
in
brackets show the
percentage of kemp.
The total medullation percentage could not be worked out due to want
of apparatus. The total weight of heterotypes has been taken to calculate
the percentage of medullated fibres. From the point of medullation shoulder
wool stands first in quality followed by neck and wither wools. On the whole
in fleece classing of the Deccan sheep at the present stage of breeding, these
E. J. BRUEN 197
three regions can safely be placed together as one quality. The side and the
back wools are almost alike except that the side wool has a greater percentage
of kemp than the back wool. The kemp is said to be an heritable character
and the students of wool and sheep advise that these should be separately
estimated. However, with the quality of wool which is under study, it is
advisable to take the total medullation as the primary factor in judging sheep
and then correct the results by other attributes in the following order of their
importance: (1) length, (2) fineness, (3) percentage of kemps, (4) crimps
(or waves), and (5) density.
Fig. 5. Contour of the fleece of the ' A ' grade Deccan sheep.
The histograph (Fig. 5) given above will show the general stand of the
coat of the Deccan sheep from region to region. It is seen that the wither
wool has the longest fibre followed by neck and side wools. The back wool
has the least length. This contour of the fleece is a common factor in the
majority of the Deccan sheep. The most defective part of the fleece is the
198
Wool Quality as the Basis of Individual Selection
back wool. In the selection of animals this defect will have to be eliminated
gradually. The britch wool in any breed of sheep is classed as the lowest
quality. This is also true of this breed and the figures of medullation given
in Table VII are self-evident.
The fineness of wool on a zone depends on the proportion of types of fibres.
The percentage of fine or coarser fibre will change the mean diameter of the
total population. Hence the proportions of the types and their quality are
of more importance than the mean diameter for all types of fibres on a zone
or in a fleece.
On the whole, it can be laid down that the fleece of the Deccan sheep
can be classed into four groups at the shearing yard:—
1. Neck, wither and shoulder wools.
2. Side and back wools.
3. Britch wool.
4. Hairy portion from the rest of the body.
5. Analysis of variance
This is an important study which shows the variation in animals, in
regions and in types of fibres. The interactions between animals and types
of fibres, types of fibres and regions and lastly between animals and regions
are worked out in Tables VIII and IX dealing with length and diameter
respectively. In these calculations the measurements of kemp fibre have
been omitted as they are a disqualification. The ewes Nos. 7, 69 and 5
have a different type of coat in different regions and as such they cannot be
treated statistically along with the rest.
TABLE VIII
Analysis of variance for length†
Variation due to
Animals
Regions
Types
Interactions
A×T
R×T
A×R
Residual
Total
Degrees
of
freedom
6
5
2
12
10
30
60
125
Total
sum of
squares
11.1208
7.6900
12.1363
2.7838
2.3637
3.8440
3.1206
43.0592
Mean square
1.8534
1.538
6.0681
0.2319
0.2363
0.1281
0.05201
Ratio
35.63**
29.56**
116.70**
4.459**
4.543**
2.462*
* Only when for 5 per cent. ** Significant, †Length in inches.
E. J. BRUEN 199
TABLE IX
Analysis of variance for diameter†
Variation due to
Animals
Region
Types
Interactions
A×R
R×T
T×A
Residual
Total
Degrees
of
freedom
6
5
2
30
10
12
60
125
Total sum
of
squares
838.25
266.402
23147.764
187.40
262.284
263.316
351.294
25316.71
Mean square
139.700
53.280
11673.882
6.246
26.228
21.943
5. 854
Ratio
15.79**
6.017**
1306.0**
0.07055
2.963**
2.478*
* Only when for 5 per cent. ** Significant. † Diameter in microns.
Referring to the tables of analysis of variance, it is evident that variation
due to animals is significant as predicted already. The regional variation
for length measurements is also very significant and the same is true of the
types of fibres. This will show clearly the reason why each type of fibre has
to be studied independently. The interactions between animals and types,
regions and types, and animals and regions are significant. This is expected
in the case of length measurements because of the sudden change in the length
level of the back wools. This significance in the case of animals and regions
is true only at the 5 per cent level. In considering the variation due to
interactions between animals and regions for diameter measurements, it will
be seen that it is non-significant and that between the types and animals it
is significant only at the 5 per cent level. This non-significance is also ex-
pected as the types of fibres and their dimensional values are the same for
animals and regions. The analysis of variance has shown that the sampling
of zones and demarking of the regions is statistically correct.
This will show how essential it is to have a large number of sheep to select
so that the desired type can be evolved out of the present heterogenous mass
of the Deccan sheep. However, within the number that is now studied
Table X gives the percentages of medullated fibres and wool in individual
200
Wool Quality as the Basis of Individual Selection
sheep shows the degree of variation in the fleece character, and points out the
ewes which should be selected for the next stage of improvement.
TABLE X
Percentage weight of wool and medullated fibres
Ewe No.
4
31
30
41
72
20
89A
Ewe No.
7
5
69
Wool
74.83
51.78
80.15
74.71
72.30
84.24
67.01
Heterotypes
14.77
31.53
17.11
20.77
24.57
12.75
12.95
Wool
42.72 (24.10 fine) (18.62 strong)
51.01 (36.77 fine) (14.24 strong)
57.92 (36. 80 fine) (21.12 strong)
Kemps
11.26
6.69
2.73
4.52
3.12
2.99
20. 02
Medullated fibres
57.27
48.97
42.05
Ewe No. 20 stands first both in regard to medullation and fineness of
fleece. Ewe No. 30 stands second although a slightly better in length mea-
surement than the previous one. Ewe No. 72 follows these two in its fleece
quality.
6. Method of recording individual and progeny performances
After studying the wool quality of the individual sheep, it is necessary
to record it in such a way that not only will it be easy to find out the life-time
performances of that sheep, but the results of its progeny, can be referred to,
for further selection or elimination. This subject has been worked out in
great detail by Dr Waters, Massy Agriculture College, New Zealand, who was
kind enough to supply the farm with the information of his card-index method.
Methods of sheep improvement are in an advanced stage in that country and
there is yet time to apply the details worked out by Dr Waters to our condi-
tions. However, a suitable method has been framed for recording wool quality
of the Deccan sheep (vide the form on page 205).