Interpreting the Sire Summary - CCA Breed Improvement

Glossary
Accuracy – used to show the reliability of an EPD. As accuracy approaches 1.00, it means that more performance
information (progeny, grand-progeny, sibs and other relatives) was used in the evaluation of a sire. As the accuracy
increases the EPD is a better predictor of the animal’s true genetic merit. PE indicates accuracy values of less than
0.15 for carcass traits.
Active Dam – any dam with at least one performance-tested progeny born within the last two years.
Active Sire – any sire with at least one performance-tested progeny born within the last two years.
Birth Weight EPD - the expected difference in average birth weight (pounds) of progeny. Birth Weight reflects
prenatal growth. Positive values indicate heavier birth weights.
Calving Ease EPD – The expected difference in average percent-unassisted calves. A larger number means a
higher percentage of unassisted calves.
Carcass Weight EPD – The expected difference in average carcass weight of progeny in pounds. A larger number
means that carcasses will weigh more at a constant age.
Contemporary Group - two or more animals of the same sex that have been born within a 90 day range, raised in
the same environment under the same management conditions.
Current Population – all calves born in the last two years.
Environment - all of the non-genetic factors that affect the life and performance of an animal.
Expected Progeny Difference (EPD) - EPDs are an estimate of how the average progeny of a sire are expected to
compare to progeny of a breed average sire for the trait of interest. EPDs predict differences and not absolutes.
They can be used to compare expected progeny performance of different animals.
Fat EPD - The expected difference in back fat thickness of progeny in millimeters. A larger number means that
carcasses will have more back fat at a constant age.
Genes - the basic units of heredity that occur in pairs and have their effect in pairs in the individual, but which are
transmitted singly from each parent to the offspring.
Genetic Correlation - a measure of how closely traits vary together genetically and reflect the effect that selection
for one trait can have on other traits. Correlations may range from -1.0 to +1.0. When two traits (e.g. weaning and
yearling weight) are positively and highly correlated to one another, successful selection for one will result in an
increase in the other trait.
Genotype - actual genetic makeup of an individual determined by its genes or germplasm.
Genotype-environment interaction - variation in the relative performance of different genotypes from one
environment to another. For example, the optimal animal (genotypes) for one environment may not be optimal in
another environment.
Genetic evaluation - a set of complex calculations (called Best Linear Unbiased prediction - BLUP) designed to
estimate the portion of variation in performance of animals which is due to genetics rather than environmental
conditions. The results of these calculations are expected progeny differences for a variety of traits on each animal
in the database.
Lean Yield EPD – The expected difference in average lean yield of progeny in percent. Lean yield is the percent of
lean meat produced in relation to the total carcass weight. A larger number means that a higher percentage of the
carcass weight will be lean meat at a constant age.
Marbling EPD – The expected difference in average marbling score of progeny. A larger number means that
progeny of the animal will have a lower average marbling score and thus express a higher degree of marbling at a
constant age.
Milk EPD – the genetic ability of a sire’s daughters to express in pounds of weaning weight in her calves due to her
maternal ability through mothering instinct and milk.