Effect of Misidentification on the Estimation of Breeding Value and Heritability in Cattle1

Abstract

For daughter groups of 15 test bulls, controls of paternity were performed by using blood group factors and biochemical polymorphisms. Data of incorrectly assigned daughters influenced the estimation of breeding values, heritabilities and correlations for milk performance traits. Formulae are given that show the effects of variable misidentification rates on estimation of breeding values, selection intensities, heritabilities, and genetic gains. For example, for milk fat yield, the genetic gains drop at a misidentification rate of 15% between 8.7% (for h2 = .5) and 16.9% (for h2 = .2) below values attained without misidentifications. Consequently, decreasing misidentification rates in progeny of test bulls can be used to diminish the progeny size per test bull for constant genetic gain, to achieve more precise ranking of all or distinct test bulls according to their "true" breeding values and(or) to increase the number of test bulls by using the same amount of test inseminations and the same precision of ranking. Actions to reduce misidentification rates in cattle populations are discussed.

Impact of Paternity Errors in Cow Identification on Genetic Evaluations and International Comparisons

“…New reputed daughters assigned to high-merit bulls through random replacement were expected to be of generally lower merit than the true progeny that were replaced. Estimated annual genetic trends decreased by 11 to 15% overall (Table 3), which was similar to results from the simulation study of Gelderman et al (1986) but more than found through simulation by Israel and Weller (2000). The observed decrease in annual trend was larger than Israel and Weller's (2000) probably because truly top bulls would not have been used as heavily here, had selection been based on their biased genetic evaluation.…”

“…Paternity errors are expected to bias estimation of genetic parameters (Van Vleck, 1970b), breeding values of individual animals (Israel and Weller, 2000;Van Vleck, 1970a), and genetic progress (Gelderman et al, 1986;Van Vleck, 1970a). Van Vleck (1970b) also showed that bias increased as the proportion of records with errors increased.…”

“…However, the literature suggests that this assumption is incorrect. Reported rates of paternity misidentification in various cattle populations worldwide reached almost 25%-around 5% in Israel (Ron et al, 1996), around 12% in The Netherlands (Bovenhuis and van Arendonk, 1991), 5 to 15% in Denmark (Christensen et al, 1982), 8 to 20% in Ireland (Beechinor and Kelly, 1987), and 4 to 23% in Germany (Gelderman et al, 1986).…”

“…Van Vleck (1970b) also showed that bias increased as the proportion of records with errors increased. Those studies were based on either deterministic analysis that considers the sire-daughter inheritance path (Gelderman et al, 1986;Van Vleck, 1970a and1970b) or stochastic simulation of commercial cattle populations and animal model evaluations (Israel and Weller, 2000). In the latter study, an error rate of 10% was simulated for cow paternity and resulted in decreased genetic gain and biased EBV.…”

Pedigree and marker information requirements to monitor genetic variability

“…Several studies [5,7,14] show that the misidentification rate in cattle pedigrees varies between about 3 and over 20%. Even in Lipizzan horse pedigrees where a great importance is attached to correct pedigree recording, a small number of pedigree errors has been revealed by mtDNA analysis [10].…”