Cattle Diversity by Blood Typing
With kind permission
of Dr A.P.Usha.
Extract from PhD Thesis, University of Edinburgh, 1996.
Improvement of domestic
livestock for traits of economic importance is dependent
on selection of future breeding stock whose performance
is better than that of the average population. The genetic
merit of a sire is largely determined by evaluating his
progeny. The value of such progeny test information depends
on the accuracy of the parentage records.
As a result of the
rapid development of artificial insemination in cattle,
the practice of mating cows to different bulls during the
same two consecutive heat periods has increased the risk
of unknown or uncertain pedigree. Situations which may lead
to disputed parentage include:
The risk of such errors
make it necessary to establish the parentage of individual
animals to verify their pedigree. Also, the breed societies
and herd books require verification of parentage on a routine
basis.
By the beginning of
this century, when Mendel's laws were found to be applicable
to human blood groups, animal geneticists studied the importance
of blood group genetics in livestock species, often with
a view to verify parentage. Although coat colour was previously
used for parentage
verification, blood groups were the first set of markers
widely accepted for parentage tests. In addition to the
blood groups, advances in electrophoretic separation methods
and immunochemistry enabled analysis of soluble proteins
giving additional genetic markers which could be used to
increase precision. For the past thirty years, parentage
verification has bee based on these readily identified gene
products.
The fundamental principle
of all tests for disputed parentage with the aid of a genetic
marker is that the factor carried by an individual must
be present in either or both its parents.
Blood Group Systems in cattle
The
antigenic moiety/determinant detected by a monospecific
reagent is termed a blood group factor or a specificity.
Each specificity is encoded by a single gene. A group of
factors coded by linked genes occur as a unit and is termed
as a blood group system, those on an individual chromosome
are referred to as a phenogroup. The blood group phenotype
is a combination of phenogroups inherited from both parents.
Phenogroups can vary occasionally through recombination.
The B and C blood group systems in cattle are coded by closely
linked genes. The chromosomal location of different blood
group systems have been determined - see table below.
| Locus |
Chrom. |
Linkage
group |
Synteny
group |
Antigens |
Reference |
| A |
15 |
5 |
19 |
A D H Z' |
1 |
| B |
29 |
12 |
27 |
B G I1 I2
K O1 O2 O3 O4
P1 P2 Q1 Q2
T1 T2 Y1 Y2
A' B' D' E'1 E'2 E'3
F' G' I' J'1 J'2 K' O' P' Q' Y'
B" G" I" |
2, 3,
4 |
| C |
18 |
|
9 |
C1 C2
E R1 R2 W X1 C' L' |
10 |
| F/V |
21 |
7 |
|
F1 V1 |
|
| J |
11 |
2 |
16 |
J |
1, 5 |
| L |
3 |
|
6 |
L |
10 |
| M |
23 |
1 |
20 |
M M' |
6, 7 |
| S |
21 |
7 |
4 |
S1 U1
U2 H' U'1 U'2 H"
S" U" |
2, 3,
4, 8, 10 |
| Z |
8 (10ref10) |
12 |
18 (5ref10) |
Z |
2, 3,
4, 9 |
| R'/S' |
16 |
|
1 |
R'1 S' |
10 |
| T' |
19 |
|
21 |
T' |
10 |
Eleven blood groups have been recognised in cattle - some
are simple with only one antigen presented, whilst others
are more complicated. The J system is the only one to be
associated with a naturally occurring antibody - antiJ -
and the titre varies greatly according to season of the
year and the age of the animal. The antigen of the M system
is known in two forms - M and M' - one of which is dependent
on the presence of the other and is thus called a subtype.
The
B system is the most extensive blood group system, with
about 300 variants reported. Not all the phenogroups are
equally present in different breeds or herds of cattle.
Some of the blood groups are characteristic of certain breeds,
while others are common to many. For example, R1 is common
in Herefords and rare in other breeds while the B phenogroup
OTE'3K' is common in Jersey but unknown in Friesians. Thus
some phenogroups are indicative of breeds. Each animal inherits
one phenogroup from each parent, so the blood type as it
appears is a combination of two contributions. An animal
which has the blood type GY1D'O3J'K' can be formed by two
phenogroups, which are distinguished by segregation in calves,
half of which may inherit the blood type GY1D', the other
half O3J'K'. The B system provides a large number of different
genetic markers which greatly increases the sensitivity
if blood group methods in discriminating between different
populations of cattle.
Standard protocols
are used in blood typing.
Protein
polymorphism
Apart
from antigenic variation between the red cells of different
individuals, there are variations among serum proteins.
These variants are normal with respect to their biological
function and differ from each other in a few amino acids.
The variation in the serum proteins can be detected by electrophoresis.
The electrical charge of the protein molecule depends on
its amino acid content. Amino acid substitutions occurring
in proteins as a result of mutation alter the charge of
the protein, which affects their electrophoretic migration.
The
first electrophoretic protein described was S haemoglobin.
Haemoglobin and transferrin are frequently used for parentage
verification in domestic animals. Transferrin is a protein
which transports iron in the body and integrates this on
to the haemoglobin in the reticulocyte. Allelic differences
are revealed in the polypeptide chain of transferrin molecules
depending n the amount of sialic acid attached. Four alleles
- A, D1, D2, and E - are described for the transferrin protein
in British cattle. More alleles occur in other breeds, for
example, G and F in Zebu cattle. Other commonly studied
proteins include albumin, amylase, ceruloplasmin, esterases,
and alkaline phosphatase. The efficiency of parentage testing
based upon blood groups is increased by 5% when supplemented
with information on transferrin and haemoglobin polymorphism.
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References
