NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
December, 1956]
K.
S.
KRISHNAN
159
TABLE III
Comparison of different Sire Indices (Kangayam bulls, Livestock Research Station, Hosur)
Bull No.
(1)
307
306
35
90
269
231
85
391
104
50
33
34
132
554
39
47
119
Daughter-
dam
pairs
(2)
54
45
34
30
28
26
20
12
11
9
9
8
8
7
7
7
6
Dams'
Average
(3)
1673
1818
1442
1661
1645
1518
1292
1408
2421
1673
1203
1806
1729
1894
2046
1614
1873
Simple Daughter
Average
Index
(4)
1176
1245
1546
1748
1249
1182
1654
1185
1706
1717
1608
1585
1340
1073
2360
1186
2135
S.E.
(5)
101
94
91
123
97
77
90
59
180
212
115
115
148
170
482
115
289
Intermediate
Index
(6)
679
672
1650
1835
853
846
2016
962
991
1761
2013
1364
951
252
2674
758
2397
S.E.
(7)
168
170
207
217
190
164
212
161
571
362
174
347
394
391
899
320
547
Corrected Daughter
Average*
Index
(8)
1098
1155
1534
1673
1179
1148
1685
1183
1414
1639
1665
1468
1246
931
2174
1124
1999
S.E.
(9)
90
88
96
111
91
76
96
66
225
193
89
139
166
172
466
136
272
Rank according to
(4)
(10)
16
12
9
3
11
15
6
14
5
4
7
8
10
17
1
13
2
(6)
(11)
15
16
7
5
12
13
3
10
9
6
4
8
11
17
1
14
2
(8)
(12)
16
13
7
4
12
14
3
11
9
6
5
8
10
17
1
15
2
*Corresponding to the herd average of 1,400 lb.
160
NEW
SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
TABLE IV
Comparison of different Sire Indices (Tharparkar bulls, Government Cattle Farm, Patna)
Bull No.
(1)
39
26
599
24
1461
77
20
16/0
885
18
16
27
1/0
Daughter-
dam
airs
(2)
45
29
26
24
21
20
14
14
13
10
8
6
6
Dams'
Average
(3)
3340
3297
3441
3948
3594
3310
3272
3783
3484
3101
2694
3700
2625
Simple Daughter
Average
Index
(4)
2704
3128
3160
3020
3345
2780
2876
3639
2160
2673
2891
2605
3002
S.E.
(5)
172
193
261
277
315
268
211
374
181
172
256
565
721
Intermediate
Index
(6)
2068
2959
2879
2092
3096
2250
2480
3495
836
2245
3088
1510
3379
S.E.
(7)
416
423
542
511
648
438
381
864
541
351
649
1550
1394
Corrected Daughter
Average*
Index
(8)
2679
3110
3128
2951
3342
2758
2856
3582
2125
2666
2913
2554
3029
S.E.
(9)
176
193
263
283
319
261
206
385
190
168
258
539
654
Rank according to
(4)
(10)
10
4
3
5
2
9
8
1
13
11
7
12
6
(6)
(11)
11
5
6
10
3
8
7
1
13
9
4
12
2
(8)
(12)
10
4
3
6
2
9
8
1
13
11
7
12
5
*Corresponding to the herd average of 3,000 lb.
December, 1956]
K.
S.
KRISHNAN
161
TABLE V
Comparison of different Sire Indices (Sindhi bulls, Livestock Research Station, Hosur)
Bull No.
(1)
255
8
144
236
38
65
139
282
124(0)
98
56
238
136(0)
Daughter-
dam
pairs
(2)
27
25
23
18
17
12
11
11
11
10
9
7
6
Dams'
Average
(3)
4019
3651
4118
3860
3664
4029
4827
4320
3364
4499
4298
4646
2998
Simple Daughter
Average
Index
(4)
2974
4363
3192
3923
4023
3262
4261
3278
3283
3813
5083
4470
4163
S.E.
(5)
239
272
315
475
226
269
362
481
495
360
850
426
318
Intermediate
Index
(6)
1929
5075
2266
3986
4382
2495
3695
2236
3202
3127
5868
4294
5328
S.E.
(7)
497
506
713
995
396
641
509
1076
953
557
1698
1096
644
Corrected Daughter
Average*
Index
(8)
2917
4372
3117
3895
4029
3203
4060
3167
3343
3670
4976
4301
4288
S.E.
(9)
236
258
323
477
212
282
303
490
481
310
841
451
317
Rank according to
(4)
(10)
13
3
12
7
6
11
4
10
9
8
1
2
5
(6)
(11)
13
3
11
6
4
10
7
12
8
9
1
5
2
(8)
((12)
13
2
12
7
6
10
5
11
9
8
1
3
4
* Corresponding to the herd average of 3,700 lb.
162 NEW SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
TABLE VI
Comparison of different Sire Indices (Sindhi bulls, Indian Dairy Research Institute, Bangalore)
Name of
bull
(1)
Erab
Ziman
Unique
Erio
H. Gulam
Sulaiman
Tazman
Sikander
Xavier
H. Raj
Warrior
Victory
Daughter-
dam
pairs
(2)
19
19
18
13
12
10
10
9
9
7
7
6
Dams'
Average
(3)
3363
2930
2541
4117
2131
3282
2898
2542
2479
2773
3807
2679
Simple Daughter
Average
Index
(4)
2699
2629
3283
2781
2693
2843
3197
2396
3063
1810
3368
3819
S.E.
(5)
308
299
318
430
368
523
266
457
578
573
442
251
Intermediate
Index
(6)
2035
2328
4025
1445
3255
2403
3496
2250
3647
847
2929
4959
S.E.
(7)
617
575
729
853
767
723
507
1152
1499
973
1061
651
Corrected Daughter
Average*
Index
(8)
2577
2587
3312
2519
2798
2735
3160
2425
3104
1797
3163
3823
S.E.
(9)
302
279
324
424
362
452
242
492
628
525
462
236
Rank according to
(4)
(10)
8
10
3
7
9
6
4
11
5
12
2
1
(6)
(11)
10
8
2
11
5
7
4
9
3
12
6
1
(8)
(12)
9
8
2
10
6
7
4
11
5
12
3
1
*Corresponding to the herd average of 2,700 lb.
December, 1956]
K.
S.
KRISHNAN
163
TABLE VII
Comparision of different Sire Indices (Hariana bulls, Government Cattle Farm, Hissar)
Bull No.
(1)
I
II
III
IV
V
VI
VII
VIII
IX
X
Daughter-
dam
pairs
(2)
8
8
10
9
8
7
6
7
11
5
Dams'
Average
(3)
1334
1598
1813
1156
1145
1193
1172
1737
1377
1122
Simple Daughter
Average
Index
(4)
1329
1254
1673
1349
1438
1717
1402
1667
1492
1288
S.E.
(5)
138
151
200
138
123
201
247
230
165
193
Intermediate
Index
(6)
1324
910
1533
1542
1731
2241
1632
1597
1607
1454
S.E.
(7)
222
274
440
344
213
385
84
371
364
378
Corrected Daughter
Average*
Index
(8)
1319
1167
1523
1391
1483
1748
1440
1539
1470
1340
S.E.
(9)
101
139
210
153
101
182
122
200
163
182
Bank according to
(4)
(10)
8
10
2
7
5
1
6
3
4
9
(6)
(11)
9
10
7
6
2
1
3
5
4
8
(8)
(12)
9
10
3
7
4
1
6
2
5
8
*Corresponding to the herd average of 1,300 lb.
164
NEW SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
TABLE VIII
Comparison of different Sire Indices (Gir bulls, Indian Dairy Research Institute, Bangalore)
Name of
bull
(1)
Windfall
Yakub Khan
Ranji
Wonderful
Daughter-
dam
pairs
(2)
10
8
5
5
Dams'
Average
(3)
3368
2192
2598
3189
Simple Daughter
Average
Index
(4)
3123
2163
3057
2343
S.E.
(5)
222
393
444
614
Intermediate
Index
(6)
2878
2134
3516
1497
S.E.
(7)
280
631
1063
1436
Corrected Daughter
Average*
Index
(8)
3009
2414
3182
2284
S.E.
(9)
162
383
499
672
Rank according to
(4)
(10)
1
4
2
3
(6)
(11)
2
3
1
4
(8)
(12)
2
3
1
4
*Corresponding to the herd average of 3,000 lb.
December, 1956]
K.
S.
KRISHNAN
165
These results can be seen clearly by a comparison of the mean square errors for
the three indices for all six herds (Table IX). The mean squares for the intermediate
and the simple average indices, when averaged over all the herds, were about 437
and 103 per cent respectively of the mean square for the corrected index. The
standard error of the corrected index, when averaged over all sires, was only 45.4
per cent of the standard error for the intermediate index and 97.8 per cent of the
error for the simple daughter average index.
TABLE IX
Pooled mean square errors for the different indices
(10 lb. unit)
Herd
1. Kangayam (Hosur)
2. Tharparkar (Patna)
3. Sindhi (Hosur)
4. Sindhi (Bangalore)
5. Hariana (Hissar)
6. Gir (Bangalore)
Pooled
d.f.
304
223
174
127
69
24
921
Mean
Simple
daughter
average
3536
13936
21177
18467
2558
10248
11547
Square
Intermediate
12166
63850
88410
80645
9425
38857
48998
for
Corrected
3173
13938
20855
17716
2189
9806
11219
The relative rankings of the bulls in each breed according to the three indices
are given in columns (10), (11) and (12) of Tables III to VIII. It may be seen
that for all the herds studied, the bull ranked first according to the corrected
index retained the same rank according to the intermediate index or to the ordinary
daughter average index. The only exception was the Gir herd, where the best
bull would have been rated as the second best if the ordinary daughter average
31 AR/56
3
166 NEW SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
index was used. For all the six herds, the worst bull would have been rated
as such according to any of the three indices. The rankings for other bulls also
are in close agreement. The values of the rank correlation of the corrected index
with the intermediate index and the simple daughter average index are given in
Table X. The rank correlations are uniformly high for all the herds, showing
thereby that the use of the simple daughter average index will seldom lead to materi-
ally different conclusions, if the object is merely to order the bulls according to
their relative merits, provided that the average production levels of the dams mated
to different bulls do not differ to a great extent. Whenever such variations are
present, or when the estimates of the sire indices are desired with a greater precision,
the corrected index is to be preferred.
TABLE X
Rank correlation between different sire indices
Herd
Kangayam (L. R. S., Hosur)
Tharparkar (Cattle Farm, Patna)
Sindhi (L. R. S., Hosur)
Sindhi (I. D. R., Bangalore)
Hariana (Cattle Farm, Hisar)
Gir (I. D. R. I., Bangalore)
Number
of
sires
17
13
13
12
10
4
Simple
daughter
average
and
intermediate
0.874
0.813
0.890
0.669
0.697
0.600
Corrected
average
and simple
daughter
average
0.918
0.997
0.984
0.909
0.964
0.600
Corrected
average
and
intermediate
0.976
0.857
0.939
0.930
0.780
1.000
DISCUSSION
For sire evaluation and other breeding studies, it is generally the practice in
foreign countries and also in some farms in India, to take the yield in the first 300
days or the complete lactation yield when the period is less than 300 days. When
such data are not available as was the case in respect of the herds other than the
Hariana—taken for illustration in this paper—Sukhatme [1944] suggested that
correction for the inequality in lactation period may be made by using the regression
technique with lactation period as the auxiliary variable. This method has been
found, however, to inflate the indices of those sires whose daughters have shown
poor performances, since poor performers generally have shorter lactation periods.
Raising the yield of daughters which have ceased to give milk much earlier than
300 days does not appear to be justified, as the shorter lactation length cannot be-
168
NEW SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
final selection of a bull as proved for extensive use, or for the selection of his sons
for further propagation should be based on a test carried out on the records of twelve
or more daughter-dam pairs. In order to provide records of 12 daughters, about
30 dams may have to be mated to a sire in order to make allowance for sex ratio,
mortality of calves, etc.
SUMMARY
The limitations of the two common measures of the transmitting ability of bulls,
viz. the simple daughter average index and the intermediate index have been dis-
cussed and an alternative index termed as the corrected daughter average index is
proposed. This index is shown to be superior to either of the indices in current
use. The detailed procedure for the calculation of the corrected index and its
standard error is illustrated with the help of the data on the Hariana herd at Hissar.
The superiority of the corrected index was also demonstrated with the help
of the data pertaining to 69 bulls from six herds. An examination of the relative
rankings of the bulls in these herds, according to the three indices, revealed close
agreement, the best and the worst bulls for a herd remaining generally the same
for all the three indices. The rank correlations between any two indices are uni-
formly high for all the herds, showing thereby that the use of the simple daughter
average index will seldom lead to materially different conclusions, if the object
is merely to order the bulls according to their relative merits, provided that the
average production levels of the dams mated to different bulls do not differ sub-
stantially. Whenever such variations are present, or when the estimates of the sire
indices are desired with a greater precision the corrected index seems to be the
appropriate one to use. Corrections for the lactation length and the order of
lactation have been discussed. The number of daughter-dam pairs required to test
a sire by the use of the proposed index has also been examined.
ACKNOWLEDGMENT
The author feels greatly indebted to Dr V. G. Panse, Statistical Adviser and
to Shri V. N. Amble, Statistician (Animal Husbandry), I.C.A.R., for their guidance
and encouragement in the preparation of this paper. He also acknowledges the
permission given by the Indian Council of Agricultural Research for making use
of the data collected under a Council scheme, and to the Heads and other staff of
the cattle breeding farms from where the data were collected. The computational
help rendered by Messrs B. B. Nayar and P. N. Soni is also acknowledged with
thanks.
REFERENCES
Kempthorne, O, and Tandon, O.B. (1953). The estimation of heritability by regression of offspring
on parent (Biometrics Vol. 9, No. 1)
Lush, J.L. (1945). Animal Breeding Plans, Iowa State College Press, Ames, Iowa
Sukhatme P.V. (1944). Note on the method of calculating Sire Index for milk production in Cattle
Indian J. vet. Sci. Vol. XIV, Part II
December, 1956]
K.
S.
KRISHNAN
169
APPENDIX I
Comparison of the relative efficiency of the three indices
Let σ 2
d and σ 2
M be the variances for the daughters and dams respectively,
b the intra-sire regression of daughter's performance on that of its dam, and
n the number of daughter-dam pairs.
The variance of the simple daughter average index is given by V(D)=I / N σ 2
D
The variance of the intermediate index is
V (I) = V (2D-M)
= 4 V (D)+ V (M)—4 cov (D, M)
= I/N [ 4σ 2
D +σ+ 2
m —4b σ 2
M ]
= I/N [ 4σ 2
D +σ 2
M (1-2h 2 )]
since h 2 =2b
The variance of the corrected index is
V (S)= V[D—b(M—A)]
= V (D)+ 2
b V(M)—2 bcov(D, M)+(M—A) 2 V(b)
= I/N(σ 2
D —b Z σ 2
M ]+(M—A) 2 V(b)
= I/N[σ 2
d —(h 2 )/4 σ 2
M ]+(M-A) 2 V(b)
The efficiency of the corrected index relatively to the simple daughter average
index is therefore,
V / V (D) / (S) =I/Nσ 2
D / I / N[σ 2 D— (h 2 ) 2 / 4 σ 2 M]+(M—A) 2 V (b)
=1 / 1— (h 2 ) 2 /4 σ 2 M / σ 2 D approximately
since the term containing V(b) is negligible. If it is further assumed that σ 2
M =σ 2
D,
this is approximately 1 / 1—( h 2 ) 2 / 4 which is greater than unity.
31 AR/56
4
170
NEW SIRE INDEX FOR MILK PRODUCTION [Vol. XXVI, Part IV,
The efficiency of the corrected index compared to the intermediate index is
given by
V(I) / V(S)=I/N[4σ 2
D +σ 2
M (1—2h 2 ) / I/N[σ 2
D —(h 2 ) 2 /4 σ 2
M ] +(M—A) 2 V(b)
= 4σ 2
D +σ 2 (1-2h 2 ) / σ 2
D — (h2)2
/
4
σ 2 M
approximatel
since the term containing V(b) is negligible. This is clearly greater than 4 if h 2 is
less than or equal to 0.5.
STUDIES ON THE SCOPE FOR IMPROVEMENT OF
BELLARY SHEEP
By
M. N. DAS*, and V. R. RAJAGOPALAN†
(Received for publication on October 20, 1955)
B ELLARY sheep which constitute one of the main breeds of wool producing sheep
available in South India are mostly found in the Bellary district of Andhra State.
They are generally of two major colour patterns, (i) all black, and (ii) white body
with black face, (hereafter designated W.B.F.). The output of wool of these
sheep is low. Moreover, the fibres are very coarse and medullated. The mature
ewes generally weigh 60 to 70 lb. The rams have a square body and do not fatten
well. When mature, a ram weighs about 120 lb. and has 4 to 7 lb. of wool output
per year.
In 1925, a flock of Bellary ewes was transferred from Hagari Farm in Bellary
district to Hosur Farm with the object of raising through controlled breeding on the
farm, a flock which would be hardy and pure white and would give a fair yield of
wool. The information regarding the breeding of these sheep in the Hosur Farm for
eight years was given by Littlewood [1936] as follows:
(a) Matings of pure black ram with black ewes produced on an average seven
black lambs to one W.B.F. lamb.
(b) Matings of W.B.F. rams and ewes resulted in black and W.B.F. lambs
in the ratio of 1: 3.6. Pure white lambs also could be obtained through
such matings in the proportion of about 1 in 25.
(c) Pure white lambs were found to be of poor constitution, so much so that
the majority of them died before the age of four months.
(d) The breed responded well to good management and the average annual
yield of the breed increased from 1½ lb. to 2½ lb. when transferred from
Hagari to Hosur Farm.
As the pure white lambs were constitutionally very weak, the objective of raising
a pure white flock failed. Efforts were then directed towards raising a flock having
white body but a coloured face with fair amount of wool. A detailed investigation
for exploring the possibilities of improving Bellary sheep through selective breeding
and through grading up by means of white bodied Bikaneri rams was conducted
at the Hosur Livestock Research Station from 1938 to 1952 with financial assistance
from the I.C.A.R. The results of this investigation are described in this article.
* Statistician, I. C. A. R., New Delhi
† Director of Animal Husbandry, Madras
171
31 AR/56
172
IMPROVEMENT OF BELLARY SHEEP [Vol. XXVI, Part IV,
MATERIAL
The work on the scheme started with two flocks of Bellary sheep. The foundation
of the pure bred flock consisted of 58 farm-bred and 24 purchased Bellary ewes-
all, excepting 12, of which were white-bodied with black face, the remaining all black.
The other flock, composed of 100 black Bellary ewes (all purchased) formed the
foundation of the stock to be graded up with white-bodied Bikaneri rams purchased
from Hissar. During the 14 years of the scheme four generations of sheep were
raised from either flock, the number of lambs born in each generation are
given in Table I.
TABLE I
Distribution of lambs born in the different generations
Flocks
Bellary Flock
Graded Flock
Kind
Male
Female
Total
Male
Female
Total
Generation
I
199
202
401
149
142
291
II
65
70
135
79
109
188
III
18
26
44
38
56
94
IV
4
5
9
17
12
29
TOTAL
286
303
589
283
319
602
The ewes were mostly mated during the months of April and May. Those
which did not conceive in this season, together with others which matured in Septem-
ber-October, were mated during these latter months. Sire-daughter mating was
avoided in order to reduce inbreeding. The ewes were shorn twice a year, once
in the month of March and again in October. The lambs were weighed at birth and
thereafter fortnightly up to the age of six months.
The stud rams were given 1 lb. of concentrates daily throughout the year. All
the ewes were given 1 lb. of concentrates daily throughout the year except in the
months of September to November, when enough of grazing was available. Culling
was reduced to the barest minimum in order to permit a proper, study of the scope
for improvement through selection. During the entire period, only 17 pure Bellary
lambs out of 303 and 28 graded lambs out of 318 were culled. There was no culling
of the adult female stock.
December, 1956] M. N. DAS AND V. R. RAJAGOPALAN 173
The salient findings from a statistical examination of the data pertaining to the
two flocks are presented in the following sections separately in respect of the different
aspects studied.
Colour pattern of sheep
At the outset, the findings as regards the colour pattern of the two flocks in
different generations may be briefly summarised as follows :
In the case of the pure bred Bellary flock, the progenies of W.B.F. ewes in all the
generations showed segregation into three patterns, pure white, W.B.F. and black
in the proportions of 1 : 3 : 1 ; those of the black ewes were of two colours, viz.
W.B.F. and black in the ratio 1 : 1. The actual distribution was as shown below
together with the values of x 2 obtained on the hypothesis that the colours were
distributed in the ratio 1 : 3 : 1.
TABLE II
Frequencies of the progenies having different colours
Dams (W.B.F.)
Foundation ewes
First generation
Second generation
Polled
Black dams
Over-all generations
White
80
13
10
108
White body
24
W.B.F.
228
48
22
298
Black
90
24
7
121
Black
27
x 2 on 2 d.f.
1.86
2.67
.78
3.41
The distribution of colour patterns among the graded progenies varied in the
different generations. The progenies in the first generation had mixed colour, i.e.
mixtures of black and white and of black and brown in 92 per cent of cases, black
colour in 3 per cent of cases and W.B.F. in 5 per cent of cases. The mixed coloured
progenies of the first and second generations produced W.B.F. and mixed progenies
in the ratio 5 : 1. The W.B.F. progenies of the second generation again produced
both W.B.F. and mixed progenies in the ratio 4 : 1. Thus about 80 per cent of the
lambs born as a result of repeated crossings with Bikaneri rams had white fleece.
It may, in this sense, be claimed that both the policies of breeding could attain a fair
degree of success so far as fleece colour was concerned. The data pertaining to
colour pattern offer an opportunity to study the inheritance of the character in
question in Bellary and Bikaneri sheep. This aspect of the problem is being studied.
174 IMPROVEMENT OF BELLARY SHEEP [Vol. XXVI, Part IV,
Mortality of lambs
The success of any breeding policy in sheep depends to a large extent on the
effective control over mortality of lambs. The failure of the policy of evolving a pure
white flock of ewes reported by Littlewood was actually due to the high mortality
among pure white lambs. In the present case, the overall mortality of the female
progenies of less than one year of age was 37 per cent and 27 per cent respectively,
in the pure breed Bellary and graded flocks.
The higher mortality rate of the progenies in the pure bred flock was in this case
also due to the high mortality of the pure white lambs. It is interesting to note
that no such adverse effect could be found in the case of the graded progenies of the
same colour. Table III shows the mortality of below one year of age of the female
progenies of different colours.
TABLE III
Mortality of lambs born in different generations
Colours
Pure white
White with black face (W.B.F.)
Mixed
Black
Over-all
Pure Bellary progenies
No. born
64
169
—
70
303
Per cent
dead in
less than
one year
57.8
35.3
—
25.7
37.3
Graded progenies
No. born
35
116
164
3
318
Per cent
dead in
less than
one year
37.1
33.6
20.7
33.3
27.4
It should be mentioned that the pure white Bellary lambs either died or were
culled due to poor health before maturity. All other lambs including the pure
white graded lambs were free from such adverse effect.
The rates of mortality of the lambs in the four different generations did not
differ materially in either flock (x 2 =0.36 and 5.57 for 3 d.f. each).
Wool yield
One of the main drawbacks of the Bellary breed is its low wool yield. As stated
earlier, the annual average yield is about 2½ lb. From the data collected in the
scheme, it has been found that the average yield of pure Bellary flock remained of
December, 1956]
M.
N.
DAS
AND
V.R.
RAJAGOPALAN
175
the same order but that of the graded flock increased to 3 lb. The life-time per-
formances of 75 ewes of Bellary flock and 126 ewes of the graded flock are summarised
in Table IV.
TABLE IV
Life-time performance of ewes
Bellary flock
No. of ewes
Av. No. of clips per ewe
Av. yield per clip per ewe (oz.)
Total yield per ewe (lb.)
75
7.5±.43
19.2±.26
9.1±.52
Graded flock generation
1
97
7.1
23.9
10.6
2
26
8.0
25.9
12.9
3
3
10.3
27.1
17.5
Overall
126
7.3±.37
24.4±.25
11.1±.57
In order to see how in the course of the different generations the yield changed
specially in the graded flock, a detailed study for generationwise comparisons was
undertaken. The variate considered for such comparisons in the Bellary flock was
the total yield from the first two clips as it was found that it bears a high correlation
of the order of .75 with the life-time yield of the ewes. In the graded flock the yield
of wool in the third and fourth clips together, was taken for the comparisons because
of the fact that in the case of some of the ewes of this flock only one clip, instead
of the normal two, had been taken in the first year.
In the pure Bellary flock as might be expected no generation to generation
variation could be found. The relevant results are summarised in Table V.
TABLE V
Pure Bellary flock : yield of first two clips (in oz.)
Generation
Foundation stock
First
Second
No.
56
65
12
Average
43.2
31.6
34.2
S.E.
0.94
0.96
2.24
It is clear from the Table V that the foundation stock yielded much more than
the subsequent progenies. A possible explanation for this may be that whereas the
foundation stock consisted of ewes selected on the basis of their performance, they
were not uniformly of superior genetic merit as a consequence of which their un-
selected progeny did not have an equally high average yield. The poor prepotency
of the rams selected to head these ewes could also be a contributory factor.