The variance of true breeding value of the animals selected on the basis of EBV can be expressed as:
where * denotes values after selection, G is true breeding value, [[sigma].sub.G.sup.2] is the variance of G before selection, k is the proportional reduction in the variance of the selection criterion due to selection, and [r.sub.EBV.sup.2] is the reliability of EBV.
Regression coefficients of true breeding values on the GEBV of preselected bulls in the reference population (1) Bulls preselected according to PA (2) (progeny-testing 50 daughters per test bull) Heritability No.
This approach requires correlation of the true breeding value
and the GEBV to define every genomic trait rGBV.
Every year about 70% of female offspring born stayed in the herd as replacements and the rest were removed and only 5% of the top male calves were selected based on simulated true breeding value to be used as sires of the next generation.
Using the following equations and parameters true breeding value for milk yield trait was simulated (Jahanbakhshi et al.
Genetic trend: Genetic trend of milk yield was computed as regression of true breeding values on year for three scenarios.
Selection was made based on the true breeding value (relative weights for each trait should be entered into the program via a parameter file), phenotypic value (relative weight needed), and estimated breeding value (relative weight needed).
Thereafter, it was selected based on phenotypes, estimated breeding values, and/or true breeding values. Heifers were also selected based on their phenotypes during the first 3 years and later changed according to each selection method.
In the simulation study of Strabel and Misztal (1999), RR models were significantly better than an analysis of 305d in terms of correlation between estimated and true breeding values
.To analysis the date of SCC trait, we normalized the SCC distribution by a logarithmic transformation.
Accuracy of breeding value estimates are represented as the correlation between true breeding values and estimated breeding values and 1,000 replicates were processed for each case to estimate the accuracy.
For the low heritability model ([h.sup.2] = 0.10), the breeding values estimated using genomic information (GEBV) were generally more highly correlated to the true breeding values than those estimated using pedigree information (PEBV).