MICROSATELLITE MARKERS FOR PEDIGREE VЕRIFICATION IN CATTLE

Abstract

In order to achieve efficient implementation of the breeding programs that include selective reproduction, cor- rect pedigree information and relationships between the animals is the basic condition. Breeding strategies in domes- ticated livestock are based on animal model evaluations, which include all known genetic relationships between the animals in the calculations. However, as demonstrated in some studies, the main assumption of this model for achiev- ing unbiased evaluations – that all pedigrees and relationships are correctly recorded, is not always fulfilled. Misiden- tified animals are expected to bias the estimation of genetic parameters and breeding values and can lead to loss in se- lection response and reduced genetic progress as they are a function of the number of misidentified progeny. Errors in pedigrees could also result in incorrect decisions about selective mating of the animals, which could increase the in- breeding depression. In the past, parentage/paternity testing in cattle has been carried out through the blood group and the protein polymorphism analysis, but because of some drawbacks, these tests have been replaced with new ones that are based on detection of certain "genetic markers". Most informative and most commonly used are the microsa- tellite markers (Short Tandem Repeats) which are highly polymorphic and are located on the noncoding intron re- gions of the bovine genome. The advantage of microsatellite based tests is that theoretically any sample containing nuclear DNA can be used for analysis, and when genotyping recommended set of markers, the accuracy of the test is much higher as the probability of detecting mistaken parentage is a direct function of the polymorphism of the mark- ers used. The research of the cattle genome conducted in the past resulted in identification of several thousand mi- crosatellite loci, among which nine most informative are recognized by the International Society for Animal Genetics (ISAG) as "international marker set" and are recommended as a minimal panel to be included in cattle pedigree veri- fication in order to facilitate the record exchange between laboratories.