176
Breeding Experiment with Goats
comparison made with regard to the first and the
second progeny, shown in Table XV, gives the same
result. Both the tables show that selective breed-
ing on the side of the dams is without effect and
suggest that there is possibly no correlation bet-
ween the performances of the dams and the daugh-
ters. This is actually found to be the case as will
be seen from the values of the coefficient of corre-
lation shown in Table XVI. Six of the nine values
of the coefficient of correlation are negative and
the remaining three are positive but all of them are
small and non-significant indicating no real asso-
ciation between the performances of the dams and
their daughters.
TABLE XVI
Coefficients of correlation between the performances
of dams and daughters
Foundation stock and
first progeny
First progeny and
second progeny. First
lactation
First progeny and
second
progeny.
Second lactation
Total
milk
yield
oz.
(1)
+0.170
+0.171
—0.162
Average
milk yield
per day
of lacta-
tion oz.
(2)
—0.270
—0.005
—0.397
Average
milk yield
per day of
kidding
interval
oz.
(3)
—0.012
+0.064
—0.266
The above analysis would indicate that the foun-
dation stock had a low genetic variability. This
suggestion is also supported by the fact that the
values of the standard deviation of the three
characters in successive progenies have not signi-
ficantly changed. It is even possible to estimate
approximately the amount of genetic variability
present in the material by separating the total
sum of squares into the differences between indivi-
duals, their lactations and the interaction, as shown
in Table XVII. The extent to which the indivi-
duals have differential capacity to produce milk
(when averaged over the three lactations) is
TABLE XVII
Analysis of variance of total milk yield of goats of
the first progeny which have completed
three lactations
Cause of variation
Between does . .
Lactation order .
Residual . .
Total .
D. F.
16
2
32
50
Sums of
squares
135677631
19106175
141372459
296156266
Variance
8479852
9553081
4417889
measured by the sum of squares 1, 35, 67, 76, 31
with 16 degrees of freedom. If there had been
only random variation between individuals, this
sum of squares would have been 4, 41, 78, 89 × 16 =
70, 68, 62, 24. The difference between 1, 35, 67, 76,
31 and 70, 68, 62, 24=64, 99, 14, 07 is a measure of
the variability between individuals excluding
random variations and the ratio of this to the total
sum of squares measures the extent to which the
genetical factors affect the milk production. It
can, therefore, be said that only about 22 per cent
of the variance is ascribable to hereditable causes.
It is clear that the absence of improvement
observed in the farm herd is mainly due to the un-
fortunate selection of both the purchased and the
farm-bred bucks. If the bucks had been really
good transmitters then even with low hereditable
variability in the does, we should be justified in
expecting improvement. But, as the results of
progeny tests show, neither the original nor the
farm-bred bucks appear to possess genes for dis-
tinctly higher level of milk production. There is a
suggestion that in comparison with the worth of the
other sires, sire No. 48M was probably a good trans-
mitter; but the farm-bred bucks were definitely
poor.
To conclude, the lack of distinct improvement is
largely due to (i) the indifferent performance of the
foundation bucks and (ii) the low genetic variabi-
lity in the foundation dams. Periodical progeny
tests would have revealed pre-potency of the differ-
ent sires and suggested suitable changes in regard
to their use. A study of the genetic variability in
the successive generations would have revealed the
potentiality for improvement of the material and
also suggested suitable breeding plan. Another
factor contributing to the lack of progress is the
use of too few bucks to start with. In the absence
of knowledge of the breeding worth of the bucks,
the chance of locating superior individuals on con-
formation basis is necessarily small. Consequently
it would have been desirable to start with a larger
number in order to hold out a reasonable chance of
securing a proved buck. The herd too was of small
size while the mortality amongst the kids was high
giving few corresponding lactations for conclusive
comparisons. If culling had been practised, parti-
cularly on conformation basis and only partial
records maintained, it would not have been possible
to carry out the analysis on the generation basis
which has been done here and thus assess the pro-
gress made during the last ten years.
The experiment was financed by the Imperial
Council of Agricultural Reseach.
I would like to place on record my grateful
thanks to Mr A. E. Slater, Mr B. S. Bhatia and
to Mr V. G. Pendharkar who assisted me in the
study.