Estimation of Genetic Trends in Simulated Data

Estimation of genetic trends and effect of genetic trends on sire evaluation

“…The Method 1 estimator is different from that of all other workers although inspired by Harville and Henderson (1967) and Everett et al (1967). Method 2 is the same as used by Harville and Henderson (1967).…”

Estimation of genetic trends and effect of genetic trends on sire evaluation

“…However, older sires may tend to be mated to older cows. Smith accounts for this by modifying Equation [2] so it becomes ^^^P'T/S^ " ^ ® ^DA'T/S'/-' ô Everett et al (1967) alter Equation [1] to consider the regression of age of dam on time, yielding g E(bp.^) = t + g(l -…”

“…Note that was not included in the denominator. Everett et al (1967) estimated a term, AC, defined as the bias due to culling of dams over time, and calculated as bp,^ -^alf of AC was subtracted from in their estimator which was otherwise the same as Equation [10]. It seems that AC is a phenotypic trend, not genetic as they stated, and should be regressed by heritability.…”

Intraherd prediction of beef cattle genetic values using linear model techniques

“…Extravagant interpretation is to be avoided regardless of the source of the data. The use of simulated data has become a common and accepted procedure for the study of mixed-model methodology (e.g., Everett et al, 1967;Pollak and Quaas, 1981;Famula and Van Vleck, 1982;Boyle et al, 1983).…”