NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
248 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
is only through averaging 2 or more lactations that this variability is decreased,
and therefore their reliability increased.
TABLE VI.
Authority.
Gowen (1920)
.
„ „ . .
„
(1919)
.
.
„
(1924)
.
.
Gavin (1913) . .
Data.
Jersey cows' random sample milk yield
Guernsey cows' Advanced Registry milk yield .
Holstein-Friesian cows' Advanced Registry milk yield.
Jersey Registry of merit cows' milk yield .
British Holstein cows' milk yield
....
Co-efficient of
variation.
Per cent.
26.5
24.7
24.2
23.2
16—21
Graphs 3, 4 and 5 which compare the 1st, mean 1st 2 and mean 1st 3 lactation
yields respectively with maximum yields for these 194 cows, further support the
view already expressed that the mean of 2 or more lactation yields is more reliable
than the 1st calf yield. In these graphs, each point in the dotted curve gives the
mean yields and that in the continuous curve the maximum yield corresponding
to this mean yield for the 194 cows, the mean yields being arranged in the
ascending order according to their magnitude from, left to right. In each case, a
horizontal line is drawn through the 4,000 lbs. yield point to mark the standard
for selection, it being taken that any cows that do not give a yield of 4,000 lbs.
or more in their life are not worth keeping. This is the standard of production
used to-day at most of the dairy farms where the work of herd improvement is going
on. Of the 194 cows under study, there are 37 such as do not satisfy this standard
and which, therefore, need be culled. These diagrams show the total number of
cows as well as the proportion of good, indifferent or poor yielders in them, that have
to be culled to cull all these 37 poor yielders, when cows are culled on the basis of
their 1st, mean 1st 2 and mean 1st 3 lactation yields. Evidently of these three
measures of a cow's milk-giving ability, the one on the basis of which we have to
sacrifice the smallest number of good yielders to cull the 37 poor ones is the best.
Taking 1st calf " corrected" yield only as the standard on which to cull,
Graph 3, it will be seen that to cull all these 37 poor yielders, we shall have to cull
a very large number of good producers as well—cows that for one reason or an other
gave poor yields in their first lactation, though they gave very high yields later on.
In fact, to cull these 37 poor producers all the cows that gave yields lower than
NUMBER OF COWS.
GRAPH III.—SHOWING THE RELATION OF 1ST LACTATION YIELD AND MAXIMUM YIELD.
D2
NUMBER OF COWS.
GRAPH IV.—SHOWING THE RELATION OF MEAN 1ST 2 LACTATIONS YIELD AND MAXIMUM YIELD.
NUMBER OF COWS.
GRAPH V—SHOWING THE RELATION OF MEAN 1ST. 3 LACTATIONS YIELD AND MAXIMUM YIELD
LACTATION YIELDS AS MEASURES OF A COW'S MILKING CAPACITY
249
4,000 lbs. in their very first lactation have to be discarded. This is because the
1st calf yield of a cow is not an infallible measure of her future yield. Unless a cow
actually gives a yield of at least 4,000 lbs. in her first lactation itself, one can never
be sure as to whether she will ever give a yield of 4,000 lbs. in her life. It is
likely that a cow may yield only 1,000 lbs. in her 1st lactation and 5,000 lbs. or
even more in her very next lactation, though another cow may yield a little less
than 4,000 lbs. milk in her first lactation, and may never exceed this yield in any
of her subsequent lactations, her first lactation yield itself being her highest lactation
yield.
With mean first 2 lactations " corrected " yield, Graph 4, the case is materially
different, as here to cull the 37 poor producers we need cull a much smaller number
of good producers.
With mean 1st 3 lactations " corrected "yield, Graph 5, the conditions show still
further improvement, though to eliminate all the 37 poor producers on the basis of
this standard even, we have to cull a few good producers as well. All this goes to
show that though superlative accuracy is never possible, both mean 1st 2, or mean
1st 3 lactations yield, denote the milk yielding capacity of a cow more truly than
her 1st calf yield. Also that out of the mean 1st 2 or 1st 3 lactations yield, the
latter is a more dependable indication.
Table VII presents these results on a numerical basis. It shows how the cows
under study have behaved with regard to their maximum yield after giving different
amounts of milk in their 1st, 1st 2, or 1st 3 lactations.
TABLE VII.
Milk yield of
1st lactation,
or mean milk
yield of 1st
2 or 1st 3
lactations.
Below 1,000 .
1,000—1,999 .
2,000—2,999 .
3,000—3,999 .
4,000—4,999 .
5,000 or above
Percentage of cows giving maximum yields of
When judged by 1st
lactation yield
Less
than
4,000
lbs.
25
50
26
31
..
..
4,000
to
5,000
lbs.
50
8
34
41
49
..
Above
5,000
lbs.
25
42
40
28
51
100
When judged by mean 1st
2 lactations yield
Less
than
4,000
lbs.
..
80
44
21
..
..
4,000
to
5,000
lbs.
..
20
36
44
28
..
Above
5,000
lbs.
..
..
20
35
72
100
When judged by mean 1st
3 lactations yield
Less
than
4,000
lbs.
..
50*
66.
16
..
..
4,000
to
5,000
lbs.
..
50*
20
56
23
..
Above
5,000
lbs.
..
..
14
28
77
100
* Results of only one observation in each case.
250 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
A study of this Table reveals the same story, i.e., that first calf yield is not a
good measure from which to judge the future yield of a cow, and that mean 1st 2,
or mean 1st. 3 lactations yield is definitely better in this respect. For instance, of
the cows that yielded between 2,000—2,999 lbs. milk in their 1st lactation, 26 per
cent. gave a maximum yield of less than 4,000 lbs., 34 per cent. between 4,000 and
5,000 and 40 per cent. above 5,000 lbs.; though of those that gave 3,000—3,999 lbs.
in their 1st calf, 31 per cent. gave a maximum of below 4,000 lbs., 41 per cent.
between 4,000—5,000 lbs., and only 28 per cent. above 5,000 lbs. This means that
there is a higher proportion of poor producers, and a lower proportion of high pro-
ducers in the group of cows that gave 3,000—3,999 lbs. of milk in their first
lactation than in the group that gave 2,000—2,999 lbs., though, if the 1st calf yield
were a really reliable measure of a cow's milking capacity, the case ought to have
been the reverse, i.e., cows that yielded between 3,000—4,000 lbs. in their first
lactation ought to have all given higher yields than those that gave only between
2,000—2,999 lbs. in their 1st lactation. The data for the mean 1st 2 or mean 1st 3
lactations yield shows, however, that it is free from such anomalies, the figures
being all regular and consistent.
DISCUSSION.
From the results given in the preceding paragraphs, the tentative conclusion
may be drawn that as a measure of cow's milking capability much reliance cannot
be placed on any individual lactation yield, because of its high variability, and out
of the first 4 lactation yields, the first is the least reliable. Besides, the mean yield
of 2 or more lactations is definitely more reliable than any one individual yield, the
mean of a larger number of lactation yields being more reliable than that of a
smaller number, or, in plain English, the longer is the period for which a cow has
been milked, the more certain we can be about her milking qualities.
In view of this, there does not appear to be much justification for culling cows
on the basis of their 1st lactation yield alone, for by doing so there is the definite
risk of culling some good cows, who merely on account of some unfavourable circum-
stances, have not been able to give good yields and thus show their real merit, and
of keeping some poor animals that gave a tolerable yield in their 1st lactation, but
do not show any improvement over it in subsequent lactations, the first lactation
itself being their maximum yield for life. It seems only fair that all cows should
be tried well before it is decided to discard them.
Against this view, however, it may be argued, that since the poor yielding cows
in a herd are only a source of loss to their owner, as they merely live upon the
profits of good yielders or their owner's capital, the suggestion to keep poor yielders
in a herd for a number of lactations to try them, is undesirable as it is economically
LACTATION YIELDS AS MEASURES OF A COW'S MILKING CAPACITY
251
unsound, specially under Indian conditions, where the cattle are generally poor,
good and economical cattle rare, and consequently the cost of production of milk is
too high to make dairying a business proposition at most places. It may be urged
therefore, that only the best milkers be kept and the poor ones culled without any
unnecessary loss of time or capital. The argument is no doubt- plausible, but is
defective for the following reasons :—
(1) The suggestion of keeping only the economical cows in our herds is not
practicable at the present moment. For, judged by this standard, only few Indian
cows will be worth keeping. Unfortunately, besides, we have no exact data avail-
able as yet regarding the comparative cost of production of milk of cows of different
grades of production in our country. Only very recently the Department of
Agriculture, Punjab, has started work in the economics of milk production, and
published the results of an investigation into the cost of production of milk con-
ducted at the College Dairy, Lyallpur, for the year 1930-31 [Johnston and Kartar
Singh, 1932]. The cost of production of milk came to 98.67 annas per 100 lbs. of
milk for cows averaging 4,000 lbs. milk per lactation, or approximately one anna
per lb., which is the price at which milk sells in most Indian towns to-day. This
means that a cow that produces about 4,000 lbs. milk in a lactation, just pays for
her keep— results quite in line with those of Fraser in Illinois [1930]—, or that if an
owner is to have some profit, a cow should yield higher than 4,000 lbs. milk per
lactation.
The view, that majority of the Indian cows yield much less than 4,000 lbs. milk
in a lactation on an average, is corroborated by the available records of production
of Indian cows. For instance, at the Imperial Cattle Breeding Farm, Karnal, where
the work of cattle improvement has been going on for the last 10 years or so, of the
76 Tharparkar and 65 Hariana cows that completed a lactation in 1930-31, only
14 of the former and 7 of the latter breed produced over 4,000 lbs. milk, the average
yield per animal of the 2 breeds being only 2805 and 2464 respectively, [Smith,
1930-31]. Again, even at Pusa Dairy Farm, where the work of herd building has
been going on for the last 20 years, of the 76 Sahiwal cows on the roll during 1930-
31, excluding 19 heifers calved for the first time, 5 gave over 6,000 lbs., 14 over
5,000 lbs., and 11 over 4,000 lbs. milk in 300 days [Arjan Singh Mann, 1930-31].
Both these are Government-owned farms, where the cattle are properly fed,
cared for and gradually improved, and consequently their yields are bound to be
higher. The average yield of the unimproved, half-fed country cows should be
much less, though there are no records that can be presented in support of this.
Until such time, as a definite improvement has been brought about in Indian
cows, therefore, it will not be possible to stick to the principle of keeping only the
economical ones in herd building work.
252 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
(2) No doubt the practice of keeping poor yielders in a herd is economically
unsound, but since it costs very high to rear a calf to maturity age — about Rs. 250
to Rs. 300 on an average—it is equally undesirable and economically unsound to
dispose off a cow at the very low price at which she will generally sell, (Rs. 30 to
Rs. 40), after milking her for only one lactation and without giving her a fair
opportunity to prove her worth, especially when we know how poor a measure
of her real milking capability is a cow's first lactation yield.
To the author's mind, therefore, a safer plan for all herd building work will be
not to discard any cow merely on her first lactation yield provided she is otherwise
desirable on the basis of her confirmation. She should be given at least another
trial, and only after this should any decision be made regarding keeping or culling
her. In actual practice, however, the trial need not necessarily extend over the
complete lactation, for milking the cow for only a month or so will be quite suffi-
cient to give an idea of her expected milk yield for that lactation, since as Gavin
[1912] has shown the " Revised maximum " and the total yield of a lactation are
positively and highly correlated, and the latter can be predicted from the former
with a fair degree of accuracy. No doubt, this practice if followed, will always
cause a few undesirable cows to be kept for a slightly longer period, but it seems
necessary to follow it to save the good cows from being culled on account of their
accidental poor production in the first lactation.
Even by following this plan there is the risk of culling some good producers,
but it is not possible to avoid this risk altogether, as to do it the cows will have to
be tried for four or five lactations — a practice that cannot be economical as the
gain in accuracy secured will hardly be commensurate with the expenditure incurred
in proving the cow.
SUMMARY.
A statistical study of milk records of cows of the Sahiwal breed of India, con-
ducted in order to determine the comparative reliability of different lactation yields,
as measures of a cow's milking capacity, shows that :—
1. The value of correlation coefficient between the successive lactation yields
and the highest lactation yield — the measure used in the study as an index of a
cow's milking capability — when standardised to 85 days service period, goes on
increasing with successive lactation yields, the values being +.5026 ╤.0362 in case
of the 1st, and +.6642╤.027 in 2nd, + .6666 ╤.0271 in 3rd, and +.7745 ╤.0194
in 4th. This means that as a measure of cow's milking capability, later lactations
are more reliable than the earlier ones, and that although none of the latter lacta-
tion yields may be highly reliable, yet they are all better than the 1st. In fact the
first lactation yield is very unsatisfactory as a measure of cow's milk yield.
LACTATION YIELDS AS MEASURES OF A COW'S MILKING CAPACITY
253
2. The mean of two or more lactation yields is generally a more reliable
measure than individual lactation yields, thus confirming the results obtained by
Gowen, Gavin, Tuff, and Roberts.
3. The mean of a larger number of lactation yields is more reliable than that
of a smaller number, or in plain words, the longer is the period for which a cow
has been milked, the more certain we can be of her milking qualities.
4. The individual lactation yields are less reliable as a measure of a cow's milk-
ing capability on account of their greater reliability. Taking the mean of a few
lactation yields decreases this excessive variability and therefore increases their
reliability.
5. The practice of culling cows on the basis of their first lactation yield alone,
therefore, is unjustified, as by doing so, there is the risk of culling some good cows
too, and keeping some poor animals. This study suggests that for herd improve-
ment work the ideal plan would be to try all cows well, i.e., milk them for several
lactations, before it is decided to discard them. This, however, is not practicable
as it is economically unsound to keep poor producers for unnecessarily lengthy
periods. As a compromise between the practices of culling cows in the first lacta-
tion and trying them for several lactations, the suggestion is put forward that where
a cow is otherwise desirable, she should at least be tried for two lactations. In actual
practice the trial need not extend over the complete 2nd lactation, as the cow's
behaviour in the first month of a lactation period itself, gives an idea of her per-
formance for that lactation.
REFERENCES.
Arjan Singh Mann. (1930-31). Scientific Report of the Imperial Agriculturist, Pusa.
Eraser.
Gavin.
Gavin.
Gowen.
Gowen.
Gowen
Gowen.
(1930).
(1912).
(1913).
(1919).
(1920).
(1920).
(1924).
Daily Farming. John Wiley and Sons, New York.
Journal of the Royal Agri. Society of England, 73.
Journal Agri. Science, 5, 4.
Journal Agri. Research, 16, 3.
Genetics, 5, 2.
Journal of Heredity, 11.
Milk Secretion. Williams and Wilkins, Baltimore.
Johnston and Kartar Singh. (1932). Board of Economic Enquiry, Punjab, Rural Section
Publication, 25.
Lall Chand Sikka. (1931). Indian Journal of Veterinary Science and Animal Husbandry,
1,2.
Roberts. (1928), Proceedings World's Dairy Congress, 281-287.
Smith. (1930-31). Scientific Report of the Imperial Dairy Expert, Bangalore.
Tuff. (1928). Proceedings World's Dairy Congress, 275, 281.
CONGENITAL "BLINDNESS" OF CALVES IN INDIA.
A RÉSUMÉ OF THE POSITION.
BY
CAPTAIN S. C. A. DATTA, B.Sc., M.R.C.V.S.,
Temporary Veterinary Research Officer, Imperial Institute of Veterinary Research,
Muktesar.
(Received for publication on 17th August 1932.)
(With Plates XXI—XXIII and one chart.)
The object of the present résumé is to place on record in a brief compass the
information available at Muktesar on the occurrence of a peculiar " blindness " in
calves in India, in the hope that this will stimulate interest in the condition
amongst field workers, and lead possibly to the collection of further information
regarding its incidence. The seriousness and economic importance attaching to the
problem may be appreciated from the fact that an apprehension has been expressed
by some of the authorities concerned that cattle breeding at the Military Dairy
Farm at Quetta may have to be given up entirely if the condition of " blind
calves ", which is so common there, is not successfully tackled.
Cases of this peculiar "blindness" so far encountered, can be conveniently
divided into two classes depending upon the complexity and extent of the abnorma-
lities :—
Firstly, those in which the calves are born blind, the eyes being apparently
quite normal in size, shape and structure and showing no abnormal growth which
might explain the absence of visuality. Briefly speaking, these are cases of amau-
rosis and they appear to be far commoner than the other variety.
Secondly, those in which various sizes of teratomatous growths involving vary-
ing extents of the external eye and palpebral fissure are discovered, associated with
different grades of rudimentary eyeball, which are definitely related to the defect of
sight; briefly, cases of teratoma blindness (Plate XXI, fig. 1).
It is not clear whether the cases of calves being born blind with apparently
normal eyes and those which are born bind definitely as a result of the pressure
exerted by the dermoid teratoma on the eye have the same origin, but Dr. Darling,
Chief Officer of the Imperial Bureau of Animal Genetics, to whom reference will
( 254 )
CONGENITAL BLINDNESS OF CALVES
255
again be made later in this article, thinks that the available information suggests
" the possibility of the amaurotic and teratomatous conditions being different
degrees of the same defect". These two may, therefore, be considered together,
at least provisionally, as curiously enough they have been occurring together at the
same Farm for a number of years, and the speculative theories advanced so far to
explain the unknown etiology are based on the same principles, irrespective of the
class of abnormality involved.
It has also been ascertained from the above Bureau that these cases of " blind-
ness " at Quetta are quite different from those referred to by Crew [1925] as a
" peculiar type of blindness in Holstein-Friesian cattle ". It is to be noted that
all such specimens received at Muktesar for examination and report during a period
of about ten years have been provided by the same Dairy Farm at Quetta, but it
has recently been reported that the same condition occurs in Shikarpur, Sukkur and
surrounding villages in Sindh. Some cases of "blindness" in calves, apparently
identical with those at Quetta, have also been seen in Delhi by Colonel A. Olver,
Expert Adviser in Animal Husbandry to the Imperial Council of Agricultural
Research, and cases of teratomatous formation on the eye of calves have also been
encountered at the Veterinary College Clinic in Calcutta. The occurrence of mul-
tiple cases at Quetta and in Sindh is surprising as the observable defects in the
calves show nothing that can be associated with a parasitic or bacterial genesis.
From the evidence obtained from the reports and specimens collected at Mukte
sar, the dermoid tumour is found to be usually of a small size, a slight puffiness
being noticed around the eye. The growth may be situated at the corneo-scleral
junction as shown in Plate XXI, fig. 2, or simply on the membrana nictitans or the
conjunctiva alone. If the affected calf lives long enough, the size of the tumour
increases with the growth of the animal. In some cases the tumour may be so large
as totally to occlude the palpebral fissure (Atresia palpebrarum) with no more than
a speck of the vestigial eyeball being left behind [vide Plate XXII, figs. 1 and 2].
The outer and inner canthus are both equally affected, in fact, no segment of the
eyeball appears to be exempt. The orbital cavity is unaltered on both sides and
the microphthalmic eye is found situated in a pad of connective tissue. The tumours
are composed of structures resembling skin and contain hair, hair follicles, sweat
and sebaceous glands and pigment cells [vide Plate XXIII, figs. 1 and 2].
Usually affected calves live for some days only but they may live for years, if
allowed to do so. The growths may be considered as benign since the available
records do not suggest spread by metastasis and the histological picture of the
growth reveals no characters of malignancy. The condition appears to affect the
male and the female offspring alike, although a tabular statement supplied with a