To achieve efficient implementation of the breeding programs that include selective reproduction, it is necessary to have errorless pedigree information and correct relationships between the animals in the population. Breeding strategies in domesticated livestock are based on animal model evaluations, which include all known genetic relationships between the animals in the calculations. Successful and efficient use of Progeny Testing program is a key factor for genetic improvement of the milch animals. Failure to record correct parentage can cause bias in sire evaluation by introducing errors in estimates of heritability and breeding values. Accuracy of genetic parameters and sire evaluation are dependent on correct recording of genetic relationship.
Microsatellite Markers used in parentage testing can have many different sizes and it is this variability that makes them useful for parentage analysis. All animals, including humans, have two copies of each gene. Parentage testing relies on the principle that an individual will inherit one copy from its mother and one from its father. Therefore, if a particular marker size (called an ‘allele’) is present in the calf, but absent in both of the nominated parents, then the parents must be excluded from the calf’s pedigree. Parentage testing is based on the exclusion of relationship when an animal has a genotype inconsistent to a putative relationship.
The Method involves DNA Extraction from Sire, Dam and Calf – Multiplex PCR Amplification of microsatellite markers – Capillary Electrophoresis – Comparison of Calf DNA with Sire and Dam DNA to establish relationship.
Fig: The figure illustrates what a Microsatellite Marker looks like once it has been converted to a digital image on the computer. The numbers below each peak correspond to the size of the marker and this is the digit that appears on the animal’s DNA typing report. In this simple representation it can be seen that Sire qualifies as calf has inherited its two alleles (marked green) one each from Sire and dam.