Immunogenetics and Biochemical Polymorphisms and their Application in Animal Improvement | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Immunogenetics and Biochemical Polymorphisms

• Lots of genetically controlled chemical variants found in cells and body fluids of farm animals.
• Some are antigens carried on red blood cells, known as blood groups.
• Identification through immunological procedures involving antibodies.
• Naturally occurring antibodies can be used as test substances.

• Antibodies for testing are produced by transfusing blood from individuals with a specific antigen into animals without it.
• Antibodies obtained from the blood serum of transfused animals.
• Antisera must be fractionated to produce a reagent specific for desired antigens.

• Testing based on agglutination or lysing of red blood cells when mixed with specific antisera.
• Most farm animal blood group identifications based on lysing.

• Developing a complete range of antisera requires effort and is costly.
• Only a few labs globally capable of making blood group determinations in farm animals.

• Term for molecular variants of proteins and other compounds.
• Detection through biochemical procedures like electrophoresis.
• Electrophoretic separation based on different proteins' electrical charges.

• Despite some associations with fertility, survival, or productivity, the biological significance of blood groups and polymorphisms remains a puzzle.
• Determining their functions has been challenging.
• Some combinations in families can have deleterious effects.

• Neonatal isoerythrolysis in horses due to blood group incompatibility.
• Analogy to Rh factor in humans causing hemolytic disease in babies.

Blood Groups and Protein Polymorphisms in Farm Animals

• Some farm animals show associations between specific blood groups or protein polymorphisms and reduced fertility or survival rates in certain populations or breeds.
• Research findings on these associations need confirmation in diverse populations to determine their general applicability.
• In chickens, differences in blood group loci are linked to skin graft rejection and susceptibility to avian leukosis-sarcoma virus infection.
• Studies have explored the correlation between production traits in farm animals and specific blood groups and biochemical polymorphisms.
• While some results suggest relationships in certain breeds, the variance explained by blood groups or polymorphisms is often too low for practical selection purposes.
• Blood groups and protein polymorphisms have been most useful in verifying parentage records, requiring stable and heritable characteristics expressed early in life.
• These markers are also used to study the genetic relatedness of breeds, offering unbiased insights into genetic similarities among populations.
• Genetic distances estimated through these markers can help in preserving genetic diversity in animal populations, crucial for future adaptation.
• Immunogenetics studies in cattle have significantly advanced molecular genetics and aided in parentage verification.

Blood Factors and Phenotypic Systems

• Cattle have 12 blood group systems with approximately 80 antigenic substances.
• Other animal species exhibit similar but less complex genetic systems controlling blood antigens.

Blood Groups in Different Species:

• Cattle: Have 12 blood group systems with a variety of antigens and complex genetic inheritance.
• Dogs: Possess 9 blood factors with specific typing procedures for recognition.
• Horses: Feature 20 blood group systems with distinct phenotypic characteristics.
• Pigs and Sheep: Have their own blood group systems with varying numbers of antigenic substances.

Blood Typing Procedures:

• Cattle: Typing involves hemolysis with specific systems and alleles.
• Dogs: Blood typing is through agglutination and hemolysis methods.
• Horses: Hemolysis and agglutination are common typing procedures.
• Pigs and Sheep: Blood typing techniques vary, reflecting diverse phenotypic systems.

Species and Blood Typing Procedures:

• Pigs and Sheep are commonly used in blood typing procedures.
• Agglutination, Hemolysis, and Antiglobulin are key methods used in typing blood.

Recognized Blood Group Systems:

• There are 15 recognized systems of blood groups, each with a varying number of alleles.
• These systems include A-O, B, C, D, E, F, G, H, I, J, K, L, M, N, and O systems.

Agglutinins and Blood Group Systems:

• Some agglutinins act as incomplete agglutinins, requiring antiglobulin or dextran solutions for agglutination.

Blood Group Inheritance:

• Blood group systems, like the B system, exhibit complex inheritance patterns with multiple alleles.
• Changes in antigenic combinations are rare, generally preserving the integrity of blood group systems.

Genetic Complexity of Blood Group Loci:

• Blood group loci are genetically complex, potentially composed of subloci controlling specific antigens.

Blood Group Genotypes and Phenotypes:

• Genetic systems are represented by letters, with genotypes determined by inherited antigenic combinations.

Blood Group Frequencies and Variability:

• Blood group frequencies vary widely among different breeds and types of cattle and farm animals.
• Each farm animal species possesses multiple blood group systems, with cattle having the most extensive variety.

Blood Proteins in Farm Animals:

• Various protein variants are found in farm animals, including globulins, albumins, enzymes, and hemoglobin.
• Different proteins like transferrin, albumin, esterase, and others play crucial roles in blood function.

Blood Protein Polymorphisms

• Blood protein polymorphisms in various species are actively researched, with new variants frequently discovered.
• Most blood protein polymorphisms are controlled by allelic pairs or series without dominance, known as co-dominance.
• Detection of specific substances in the blood is indicative of the presence of corresponding genes in the genotype.

Milk Proteins

• Approximately 30% of milk protein comprises casein, with three major types in cattle: a, B, and x, alongside minor types.
• The remaining protein in milk exists as whey proteins, including a-lactoglobulin and B-lactalbumin.
• Each of the five main protein types has multiple genetic variants linked to single autosomal genes.
• Starch gel electrophoresis is utilized to simultaneously identify variants of casein and whey proteins.
• Ongoing studies aim to correlate the amino acid sequences of genetic variants with specific RNA molecules.