Comparison of genomic breeding values of Holstein in the Czech Republic

In a present period are globally introduced genomic evaluations using huge number of genetic SNP markers from genetic chips and genomic enhanced breeding values (GEBV) are calculated. Goal of genomic evaluation is higher reliability of evaluation for young animals without own phenotype and using them more early in breeding. Majority of countries are now using for GEBV calculation by multi-step procedures (Meuwissen et al., 2001), which works with preselected group of genotyped animals. Linear models according BLUP and Bayesian methodology are used. Input data in evaluation are “pseudo-phenotype data” daughter yield deviations (DYD) or deregressed proofs (DRP). More advanced is the single-step procedure (ssGBLUP) (Misztal et al., 2009; Christensen and Lund, 2010) which overcomes some disadvantages of previous methods. Namely works directly with recorded phenotypes of entire nation-wide population and directly compared genotyped and ungenotyped animals, eliminates bias from preselection of genotyped animals and infl uences also breeding value of others ungenotyped animal in evaluated population.


Introduction
Small populations of dairy cattle are strongly infl uenced by import of foreign sperm and bulls.Import is frequently connected with some time delay, when already some evaluations about foreign animals are known.Therefore there is possibility to compare domestic evaluation with foreign values.
In a present period are globally introduced genomic evaluations using huge number of genetic SNP markers from genetic chips and genomic enhanced breeding values (GEBV) are calculated.Goal of genomic evaluation is higher reliability of evaluation for young animals without own phenotype and using them more early in breeding.Majority of countries are now using for GEBV calculation by multi-step procedures (Meuwissen et al., 2001), which works with preselected group of genotyped animals.Linear models according BLUP and Bayesian methodology are used.Input data in evaluation are "pseudo-phenotype data" daughter yield deviations (DYD) or deregressed proofs (DRP).More advanced is the single-step procedure (ssGBLUP) (Misztal et al., 2009;Christensen and Lund, 2010) which overcomes some disadvantages of previous methods.Namely works directly with recorded phenotypes of entire nation-wide population and directly compared genotyped and ungenotyped animals, eliminates bias from preselection of genotyped animals and infl uences also breeding value of others ungenotyped animal in evaluated population.
Purpose of this study was to compare domestic GEBV of young bulls for milk traits with theirs foreign evaluation.

Material and methods
Milk traits are evaluated from test-day records using BLUP / ssGBLUP Animal model procedures.Evaluation (Plemdat 2015) is conducted utilizing 3-lactations-RRTDM with Legendre Polynomials (LP): where: Y -test-day record of milk yield of cow in lactation k <1, 2, 3> X TD -design matrix for herd-test-days  -vector of herd-test-day contemporary groups within a herd in lactation k (fi xed eff ect) X fg, k -design matrix for fi xed average LP of lactation curve for groups of cows within management classes sharing similar environments (Zavadilová et al., 2005b) Z -design matrices for random LP of lactation curve for permanent environmental of cow and genetic eff ects of animal ƒ -LP for fi xed (fg), permanent environmental of cows (pe) and genetic eff ect of animal (an).With pe and an are connected covariance matrices of regression coeffi cients of LP (Zavadilová et

Figure 2
Correlation of domestic GEBV of young bulls with their MACE evaluation according foreign data

Conclusions
Due to persistent strong import of foreign sperm the reliability of domestic evaluation of young animals are low.This is particularly seen in evaluation of young bulls, which frequently have both parents foreign.Genomic evaluation by ssGBLUP procedure in a Czech condition helps and notably improves reliability of evaluation.
Genomic evaluation by ssGBLUP has several advantages and especially in a small populations.Increasing the reliability of evaluation according volume of information has curvilinear course.Inclusion of genomic data helps and reliability in a small population will approach to the situation in a big populations.
Domestic evaluation with foreign evaluations have medium to high correlations.Conversion of foreign EBV/ GEBV according MACE procedure is more precise than according GMACE procedure.