NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
CROSS BREEDING FOR MILK YIELD IN INDIAN CATTLE
81
selection is admirably summarised by Lush [1935], and he concludes that fifty to
sixty per cent of the heifers bred must be retained for replacement alone, in a dairy
herd. The actual number of animals available, therefore, does not limit the selec
tion intensity, and there is, in fact, much to be said in favour of a herd of mode
rate size and limited financial demands. India has suffered severely from the
abandonment, on grounds of economy, of promising breeding schemes before they
had gone far enough to be of practical utility. For this reason also, improvement
by cross-breeding has a considerable advantage over improvement by selection,
in that there is an immediate and considerable rise in milk yield, which enables a
cross-bred herd to pay for its keep, where an indigenous herd frequently does not.
Two factors, which depend largely on the design of the experiment, influence
the efficiency of selection. The first is the number of characters for which selec
tion is exercised. Consider for the moment heifers alone, of which fifty per cent
must be retained to maintain the herd. If selection is exercised on five indepen
dent characters of equal importance, the intensity of the selection exercised on
each character is no greater than if the proportion to be retained were 5/√0.5 or
eighty-seven per cent [Lush, 1935].
To put it in another way, only half the heifers can be discarded, or the herd
will be depleted. Obviously it is not possible to discard the worst half on all five
characters and it will only be possible actually to discard the worst thirteen per
cent—a very lenient culling—of each character under selection. 13×5 = 65,
and the difference between this and fifty per cent is accounted for by the fact
that of those animals which appear in the worst thirteen per cent on one
character, some will also appear in the worst thirteen per cent for other characters
also.
In the method of back-crossing here advocated, the number of characters for
which selection must be exercised is reduced to a minimum, since all characters
desired from the indigenous breed are fixed automatically by the back-crossing
process without selection, and the selection intensity for the desired Western
characters is, therefore, at a maximum.
The second factor in design to be considered, is that selection among males
is much more rigorous than among females, since among bull calves the replace-
ment percentage is probably not more than five to ten. Consequently, any
breeding method which includes the use of cross-bred bulls will permit of a corres-
pondingly improved selection intensity. This is, of course, offset by the difficulty
of evaluating males for the most important characters, namely milk-yield and
butter-fat content.
It is beyond the scope of the present paper to advocate particular foreign
breeds, but a word must be said concerning the choice of matings. It is a sound
breeding policy to avoid introducing variability unnecessarily with regard to
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THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, II
characters in which the breeder is not particularly interested. For instance, the
size and type of animal required can usually be decided beforehand from a con-
sideration of the conditions of the tract for which the scheme is to be carried out,
and a suitable indigenous breed selected. The foreign breed with which it is to be
crossed should not differ more than necessary from it in those characters. Such
matings as Sindhi × Holstein are likely to introduce far more variability in size and
form and butter-fat content than, for example, Hariana x Holstein-Freisian or
Sindhi × Jersey, and will consequently take longer to breed back to a uniform
type in which inter-breeding can be started, and from which bulls can be provided
for the improvement of cultivators' cattle.
A SUGGESTED BREEDING SCHEME
F 1
It should be remembered that the F 1 is not a segregating generation, and F 1
animals will only differ in those characters, genes for which were heterozygous
in one or both parental stocks. As such differences may be expected to be un-
important relative to the differences between the breeds, no selection need be
exercised among F 1 heifers.
Since sex is determined by the distribution of the sex chromosome, the above
statement must be modified if any sex-linked genes for milk production are carried
by the sire. The F 1 generation will then be of two types, heifers which will have
received sex-linked genes for milk production from their sire, and bulls which
will not have received them.
Evidence for sex-linkage of some of the genes responsible for milk production
has been summarized by Smith and Robison [1933], who conclude that it is very
suggestive, but not conclusive. Of the bulls used in the breeding of Western
cattle breeds some have been what is known as ' prepotent sires ' and the ex-
ploitation of these has led to their contributing a disproportionate share, com-
pared with other bulls, to the ancestry of the breed. Since prepotency for milk
production results largely from a bull's ability to transmit his dam's excellence
to his daughters, the fact that all daughters receive a sex-chromosome from their
paternal grand-dam and only half receive any given autosome from her will result
in stronger selection for any genes for milk production situated in the sex chromo-
some, than for those situated in autosomes. It is, therefore, to be expected that
a disproportionate share of the genes for milk production carried by breeds heavily
selected for that character will be sex-linked.
The importance of this conclusion for a cross-breeding scheme with Indian
cattle is that, if the effects of sex-linkage can be safely ignored, F 1 bulls are geneti-
cally as valuable as F 1 heifers for the production of the first back-cross (or quarter-
CROSS BREEDING FOR MILK YIELD IN INDIAN CATTLE
83
bred) generation, and practically, they are much more valuable, since they can
sire many calves, whereas each heifer can produce only say six or eight calves in
her life. From the summary by Smith and Robison [1933] we conclude that in
the Western breeds examined the proportion of milk-yield from sex-linked genes to
that from autosomal genes is not high enough to demonstrate their existence with
certainty. If that is so where the genetic variance for milk production is com-
paratively small (i.e., within breeds) it is likely to be at most a very small pro-
portion of the whole in a cross between two breeds differing widely in milking
capacity, so that, even allowing for sex-linkage of milk production genes to the
extent suggested by Smith and Robison's data, the loss resulting from the use of
F 1 bulls in a breeding project of the type under discussion is likely to be negli-
gible.
We suggest, therefore, that both sexes of the F 1 generation should be bred
back to the indigenous breed. Then all the available females in the herd can be
made to contribute to the back-cross generation, and the maximum number of
animals will be provided for selection. A direct check on the accuracy of the
above estimate of the importance of sex-linkage in the inheritance of milk yield
will then be possible. Since both grand-dams of all back-cross heifers are of the
indigenous breed, a figure x can be calculated for each animal representing the
increment in milk yield over the mean yield of its two grand-dams. If sex-linkage
is important, the mean of x for heifers with F 1 dams will be significantly greater
than the mean of x for heifers with F 1 sires.
First back-cross or quarter-bred
This is the first segregating generation, and selection must, therefore, be exer-
cised. We suggest that all quarter-bred bulls should be eliminated from the herd,
since the performance of their dams (in a non-segregating generation) will pro-
vide only a negligible amount of information concerning their value. All heifers
will be bred back to a good bull of the indigenous breed, and selections made on
the basis of milking performance. Two points should be noted : first the im-
portance of the indigenous bull. The fact that high milking capacity is being
introduced from the Western breed does not release the breeder from the neces-
sity of using the best available indigenous stock. What little is known concern-
ing interaction between genes in quantitative inheritance suggests that genes
causing small increments in yield in a low-yielding strain may cause much greater
increments in strains of higher milking capacity [Smith and Robison, 1931].
Secondly, the importance of selecting the quarter-bred heifers on milk production
alone. The process of further back-crossing will be relied upon to breed out any
disadvantageous characteristics which may be carried by good milking animals.
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THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, II
It is not possible to lay down in advance the intensity of selection to be exer-
cised among heifers in each generation, but it should approach on the average that
which will allow maintenance of the strength of the herd, and very little more.
Second back-cross or eighth-bred
The second back-cross animals will resemble the indigenous breed closely
in most respects. The heifers should be bred back again to an indigenous bull,
and selected as in the quarter-bred generation. The second back-cross bulls may
be relied on to sire calves almost always superior to those of Indian breeds bearing
no foreign ' blood.' They may, therefore, be used in a village cattle improvement
scheme, and if suitable arrangements are made for estimating the value of their
progeny, the best of them can be picked out and brought back into the herd.
Later generations
Heifers of the third back-cross generation should also be back-crossed to the
indigenous breed, and selected on milking performance. As soon as bulls of the
second back-cross generation have been tested (on village cattle), the best of them
may be brought in and mated to the selected cows of the third back-cross genera-
tion. Thereafter, inter-breeding will proceed among heifers selected in each
generation on their own milk yield and bulls selected on the performance of their
progeny out of village cows.
It should be remembered that when inter-breeding is commenced, all charac-
ters of importance will have to be observed, and those besides milk yield which
prove not to have been fixed by the back-crossing process will have to be fixed by
selection.
GENERAL CONSIDERATIONS
Six quarter-bred cows whose performance is recorded by Littlewood [1933]
averaged 3,995 lbs. of milk per lactation as against an average of 4,068 lbs. by
nineteen F 2 cows. The difference is negligible, so that with the advantage in
favour of the quarter-bred that the whole of the selection can be concentrated
on milk yield, the production average of the parents of a second back-cross should
be considerably higher than that of the parents of an F 3 .
The available evidence indicates that the heterozygotes of milk-yield factors
are on the average nearly intermediate between the homozygotes. (The Mt.
Hope Index gives 0.7 [Goodale, 1927]). The inter-breeding of the best of the third
back-cross animals should, therefore, result in the production of a proportion of
heifers with a higher milking capacity than their parents. The advantages of
milk production in the first generation which cross-breeding gives over selection
in an indigenous herd is increased in the breeding scheme here discussed by the
increment in yield obtainable by inter-breeding at the end of the period of back-
crossing.
CROSS BREEDING FOR MILK YIELD IN INDIAN CATTLE
85
The fear is sometimes expressed that cross-breeding between widely different
types will result in genetic incompatibility, and consequently weakly and
unbalanced animals. The risk of such misfortunes is minimised by the back-
crossing method, as it ensures the re-building of a balanced indigenous type, with
only a minimum of introduced genes. Care must be taken to watch for evidence
of linkage (repulsion) between milk-yield genes and genes of the indigenous breed
which would otherwise be automatically fixed. If such are detected, the breeder
must himself decide whether they are of sufficient importance for him to direct
his selection towards the discovery and propagation of cross-over individuals, or
whether he can afford to allow some deviation from the indigenous type in charac-
ters other than milk yield.
This breeding scheme is aimed primarily at providing superior cattle which
can be relied on to improve cultivators' stock. It is, therefore, important to decide
at what stage untested bulls can be put to village cows with confidence, not mere-
ly that on the average their effect will be beneficial, but that there is no greater
risk than with good indigenous stock that any individual will have a deleterious
influence. If the best available indigenous stock is used in the breeding scheme,
second back-cross bulls, selected for vigour and conformation similar to that of
their indigenous sires should be safe for distribution. At that stage it is suggested
that bulls should be tested for the milk production of their daughters, and the
best of them used for inter-breeding with the best third back-cross heifers. Given
the confidence of the cultivators and provided a simple method can be devised of
estimating the yield of their cows from periodic test milkings, the testing, and the
subsequent return to the herd, of the best bulls should be a practical proposition.
In conclusion, it may be remarked that the breeding method here outlined
is but a modification for Indian conditions of the methods of grading up adopted
with great success in North and South America, South Africa, and elsewhere.
The exceptionally hard conditions in India make it necessary to grade up to the
indigenous instead of to the Western breed, but there is no reason why this modi-
fication should affect the chances of success. The cattle-breeders of the great
new cattle countries have used the best bulls in the world regardless of cost. If
this was worth while when the ground lost by the accidental introduction of an
inferior animal could be regained by replacement with a better, it is much more
important that the best possible Western bulls should be used to start such a
scheme, as is here suggested, where Western blood will be introduced once only.
ACKNOWLEDGMENT
The ideas here presented first developed in the mind of the senior author as
a result of a discussion of cattle-breeding problems with Dr. Burch H. Schneider,
of the Allahabad Agricultural Institute. The granting of study leave at the
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THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, II
Institute of Plant Industry, Indore, to the junior author by the Allahabad Agri-
cultural Institute provided an opportunity of working them out. Though Dr.
Schneider does not associate himself with the views expressed, we take this oppor-
tunity of expressing our indebtedness to him for his criticisms of the manu-
script.
REFERENCES
Goodale, H. D. (1927). Am. Nat. 61, 539.
Littlewood, R. W. (1933). Ind. J. Vet. Sci. & Anim. Husb. 3, 325.
Lush, J. L. (1935). Emp. J. Exp. Agric. 3, 25.
Smith, A. D. B. & Robison, O. J. (1931). Proceedings of the International Dairy Con¬
gross, Copenhagen.
—(1933).
Bibliogr. Genet. 10, 1.
A CHECK-LIST OF THE NEMATODE PARASITES OF THE
DOMESTICATED ANIMALS IN BURMA
BY
J. BHATTACHARJEE, B.Sc., M.R.C.V.S., F.C.S.
Offg. Veterinary Research Officer, Insein, Burma
(Received for publication on 28th January 1937)
I. INTRODUCTION
ALTHOUGH attempts have been made to record the nomatode parasites of the
domesticated animals in Burma by Evans and Rennie [1910], Gaiger [1910, 1915]
and quite recently by Bhalerao [1935], yet our knowledge of these parasites is
far from being complete. The present article is yet another attempt not only to
place on record an up-to-date knowledge of these parasites, but also to encourage
collection of these parasites by those who have ample opportunities of obtaining
material, as a great deal of collecting will have to be undertaken before our know-
ledge of these parasites can be considered anything like complete.
Unless specified, all the parasites listed in this article were identified by the
author not only from the collections of the Veterinary Research Laboratory, Insein,
Burma, which were in a good state of preservation, but also from large numbers
of fresh parasites collected by him in the course of his post-mortem examinations
on many experimental animals. The host animals considered in this article are
chiefly mammals, viz., elephant (Elephas indicus), cattle (Bos indicus), buffalo
(Bos bubalus), sheep (Ovis aries), goat (Capra hircus), horse (Equus caballus), mule
(Equus asinus × Equus caballus), dog (Canis familiaris), cat (Felis catus var.
domesticus), and pig (Sus cristatus).
II. CLASS NEMATODA Rudolphi, 1808, emend. Diesing, 1861.
Family ASCARIDAE Baird, 1853.
Genus Ascaris Linnaeus, 1758.
Ascaris lumbricoides Linnaeus, 1758.
Syn., Ascaris suum Goeze, 1782.
Ascaris ovis Rudolphi, 1819.
Ascaris suilla Dujardin, 1845.
Host. Pig.
Situation. Small and large intestines.
First record of this parasite from Burma.
Ascaris vitulorum Goeze, 1782.
Host. Cattle.
Situation. Small intestine.
Recorded by Bhattacharjee, 1930 [Mitchell, 1931]
Genus Parascaris Yorke and Maplestone, 1926.
( 87 )
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Parascaris equorum (Goeze, 1782).
Syn., Ascaris equorum Goeze, 1782.
Ascaris equi Schrank, 1788.
Ascaris megalocephala Cloquet, 1824.
Host. Horse.
Situation. Small intestine.
First record of this parasite from Burma.
Genus Toxocara Stiles, 1905.
Toxocara canis (Werner, 1782).
Syn., Lumbricus canis Werner, 1782.
Ascaris marginata Rudolphi, 1802.
Belascaris marginata Railliet and Henry, 1911.
Host. Dog.
Situation. Oesophagus, stomach, small intestine.
First record of this parasite from Burma.
Toxocara lonchoptera (Diosing, 1851).
Syn., Strongylus elephanti Rudolphi, 1819.
Ascaris lonchoptera Diesing, 1851.
Belascaris lonchoptera Leiper, 1911.
Host. Elephant.
Situation. Bile-ducts.
Recorded by Evans and Ronnie [1910]. Evans [1910].
Gaiger [1910], Bhalerao [1935]. None in the laboratory collection.
Family OXYURIIDAE Cobbold, 1864.
Genus Oxyuris Rudolphi, 1803.
Oxyuris equi (Schrank, 1788).
Syn., Trichocephalus equi Schrank, 1788.
Lepturis curvula Schlotthaubor, 1860.
Oxyuris curvula Rudolphi, 1803.
Oxyuris mastigodes Nitzsch, 1857.
Host. Horse.
Situation. Caecum, colon.
Also recorded by Gaiger [1910], Bhalerao [1935]
Family TRICHURIDAE Railliet, 1915.
Genus Trichuris Roederor, 1761.
Trichuris ovis (Abildgaard, 1795).
Syn., Trichocephalus ovis Abildgaard, 1795.
Trichocephalus affinis Rudolphi, 1802.
Trichuris affinis Rudolphi, 1802.
Host, Cattle, sheep goat.
Situation. Caecum, colon.
NEMATODE PARASITES OF THE DOMESTICATED ANIMALS IN BURMA
89
Trichuris ovis (Abildgaard, 1795)—contd.
Recorded by Bhattackarjee, 1930 [Mitchell, 1931].
Family ANCYLOSTOMIDAE (LOOSS, 1905).
Genus Ancylostoma (Dubini, 1843).
Ancylostoma caninum (Ercolani, 1859).
Host. Dog.
Situation. Small and large intestines.
Recorded by Bhattacharjee, 1930 [Mitchell, 1931].
Genus Bathmostomum Railliet and Henry, 1909.
Bathmostomum sangeri (Cobbold, 1879).
Syn., Dochmius sangeri Cobbold, 1879.
Uncinaria sangeri Cobbold, 1879.
Uncinaria os-papillatum Piana and Stazzi, 1900.
Host. Elephant.
Situation. Caecum, intestine.
Recorded by Gaiger [1910], Bhalerao [1935]. None in the laboratory
collection.
Genus Grammocephalus Railliet and Henry, 1910.
Grammocephalus varedatus Lane, 1921.
Syn., Grammocephalus clathratus (Baird, 1868).
Nematode No. 1. Evans and Rennie, 1910.
Grammocephalus intermedius Neveu-Lemaire, 1924.
Host. Elephant.
Situation. Bile-ducts.
Recorded by Evans and Ronnie [1910], Khalil [1922], Bhalerao [1935].
None in the laboratory collection.
Family METASTRONGYLIDAE Leipor, 1908.
Genus Dictyocavlus Railliet and Henry, 1907.
Dictyocaulus filaria (Rudolphi, 1809).
Syn., Strongylus filaria Rudolphi, 1809.
Host. Goat.
Situation. Bronchi.
Recorded by Giles, 1892, [Bhalorao, 1935].
None in the laboratory collection.
Dictyocaulus viviparus (Bloch, 1782).
Syn., Strongylus micrurus (Mehlis, 1831).
Host. Cattle.
Situation. Bronchi.
Recorded by Bhattacharjee, 1930 [Mitchell, 1931].
Family STRONGYLIDAE Baird, 1853.
Genus Chonianaium Railliet, Henry and Bauche, 1914.
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Choniangium epistomum (Piana and Stazzi, 1900).
Syn., Sclerostoma epistomum Piana and Stazzi, 1900.
Asifia vasifa Lane, 1914.
Host. Elephant.
Situation. Large intestine.
Also recorded by Meggitt, 1933 [Smith, 1933].
Genus Decrusia Lane, 1914.
Decrusia additicta (Railliet, Henry and Bauche, 1914).
Syn., Strongylus additictus Railliet, Henry and Bauche, 1914.
Decrusia decrusi Lane, 1914.
Host. Elephant.
Situation. Large intestine.
Also recorded by Meggitt, 1933 [Smith, 1933].
Genus Equinurbia Lane, 1914.
Equinurbia sipunculiformis (Baird, 1859).
Syn., Sclerostoma sipunculiforme Baird, 1859.
Cylicostomum sipunculiforme Railliet, Henry and Bauche, 1914.
Nematode No. 4. Evans and Ronnie, 1910.
Host. Elephant.
Situation. Intestine, caecum.
Also recorded by Evans and Rennie [1910]. Railliet, Henry and Bauche,
[1914]. Meggitt, 1933 [Smith, 1933], Bhalerao [1935].
Genus Murshidia Lane, 1914.
Murshidia falcifera (Cobbold, 1822).
Syn., Strongylus falcifer Cobbold, 1882.
Nematode No. 3. Evans and Rennie, 1910.
Host. Elephant.
Situation. Caecum.
Also recorded by Evans and Rennie [1910]. Railliet, Henry and Bauche,
[1914]. Meggitt, 1933 [Smith, 1933], Bhalerao [1935].
Murshidia indica (Ware, 1924).
Syn., Pterydopharynx indica Ware, 1924.
Host. Elephant.
Situation. Caecum.
Also recorded by Meggitt, 1933 [Smith, 1933].
Murshidia murshida Lane, 1914.
Host. Elephant.
Situation. Caecum, large intestine.
Also recorded by Meggitt, 1933 [Smith, 1933].
Genus Oesophagostomum Molin, 1861.
NEMATODE PARASITES OF THE DOMESTICATED ANIMALS IN BURMA
91
Oesophagostomum columbianum (Curtice, 1890).
Host. Cattle, sheep, goat.
Situation. Caecum, large intestine.
Also recorded by Giles, 1892, [Bhalerao 1935]. Bhattacharjee, 1930 [Mitchell,
1931].
Oesophagostomum radiatum (Rudolphi, 1803).
Syn., Strongylus inflatum (Schneider, 1866).
Oesophagostomum dilatatum (Railliet, 1896).
Oesophagostomum vesiculosum Ratz, 1898.
Oesophagostomum bovis Schnyder, 1906.
Host. Cattle, buffalo.
Situation. Large intestine.
Recorded by Bhattacharjee, 1930 [Mitchell, 1931].
Oesophagostomum venulosum (Rudolphi, 1809).
Syn., Strongylus venulosus Rudolphi, 1809.
Host. Goat.
Situation. Large intestine.
First record of this parasite from Burma.
Genus Quilonia Lane, 1914.
Quilonia renniei (Railliet, Henry and Joyeux, 1913).
Syn., Evansia renniei Railliet, Henry and Joyeux, 1913.
Nematevansia renniei Ihle, 1919.
Quilonia quilona Lane, 1914.
Host. Elephant.
Situation. Caecum, large intestine.
Also recorded by Evans and Rennie [1910]. Railliet, Henry and Joyeux,
[1913]. Meggitt, 1933 [Smith, 1933], Bhalerao [1935].
Quilonia travancra Lane, 1914.
Syn., Evansia travancra Railliet, Henry and Bauche, 1915.
Nematevansia travancra Ihle, 1919.
Host. Elephant.
Situation. Caecum, large intestine.
Also recorded by Meggitt, 1933 [Smith, 1933].
Genus Strongylus Mueller, 1780.
Strongylus equinus Mueller, 1780.
Syn., Sclerostomum equinus Looss, 1900.
Strongylus armatus Rudolphi, 1802.
Sclerostomum quadridentatum Sticker, 1901.
Host. Horse, mule.
Situation. Caecum, colon.
Also recorded by Gaiger [1910, 1911]. Boulenger [1921], Bhalerao [1935].
Genus Trichonema Cobbold, 1874.