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ABSTRACT
A total of 6040 Israeli Holstein cows from 181 Kibbutz herds listed as progeny of 11 sires were genotyped for 104 microsatellites. Seventeen markers were deleted due to a frequency of erroneous genotypes >1%, leaving 160,470 valid genotypes. Conflicts between the putative sire and daughter in at least 2 markers and for at least 10% of the markers genotyped per cow were required to reject paternity. Cows that did not meet the requirements for paternity confirmation or rejection were deleted from further analysis. The frequency of rejected paternity was 11.7%. The effects of recorded sire, birth year, geographical region, herd, and inseminator on the frequency of paternity rejection were analyzed with linear and nonlinear models. Only the effects of inseminator and recorded sire were significant in all models tested that included these effects. The main causes of incorrect paternity recording appear to be inseminator recording mistakes, and possibly mistakes with respect to semen labeling at the AI institutes. Incorrect paternity recording due to multiple inseminations by different sires could explain, at most, 20% of the paternity mistakes. Instituting a system of quality control, especially at the level of the inseminator, should reduce paternity errors to no more than 8%, and increase genetic progress by at least 1%.
(Key words: paternity error, DNA microsatellites, dairy cattle, Israeli Holstein)
Abbreviation key: Ex = exclusion probability, ISAG = International Society of Animal Genetics.
INTRODUCTION
Correct pedigree information is paramount in a successful breeding program and its importance has increased with the introduction in 1990 of individual animal models for national genetic evaluations. Even though pedigree assignments are generally not questioned, several studies have shown that the proportion of errors in sire identification varies from a few percent to as much as 22% (Christensen et al., 1982; Geldermann et al., 1986; Bovenhuis and van Arendonk, 1991; Ron et al., 1996; Visscher et al., 2002). These mistakes reduce the rate of genetic progress (Van Vleck, 1970a,b; Israel and Weller, 2000; Banos et al., 2001; Visscher et al., 2002).
Christensen et al. (1982) give the following reasons for errors in paternity recording: 1) mistakes by AI institutes in labeling semen; 2) AI technicians incorrectly identifying semen samples; 3) the insemination of cows already pregnant by a previous insemination;...