Which statement best defines the expected progeny difference (EPD) for a trait?

Which statement best defines the expected progeny difference (EPD) for a trait?

• A. The average performance of the trait across the population.
• B. The difference between a sire's and dam's phenotype for the trait.
• C. The standard deviation of progeny performance.
• D. The expected progeny difference is the expected performance of the progeny of a parent, expressed as a deviation from the mean.

Answer: (D)

EPD represents the expected difference in performance of a parent’s offspring compared with the population mean for a trait. It isolates additive genetic merit and is estimated from pedigree and progeny data to separate genetic effects from environmental influences. Because it’s expressed as a deviation from the mean, a positive EPD means the progeny are expected to perform above average for that trait, while a negative EPD means below average. This is different from the overall population average, from any simple difference between sire and dam phenotypes, or from a measure of variation like a standard deviation. The idea that the EPD reflects the expected progeny performance of a parent, expressed as a deviation from the mean, is what makes it a useful tool for selection.

EPD represents the expected difference in performance of a parent’s offspring compared with the population mean for a trait. It isolates additive genetic merit and is estimated from pedigree and progeny data to separate genetic effects from environmental influences. Because it’s expressed as a deviation from the mean, a positive EPD means the progeny are expected to perform above average for that trait, while a negative EPD means below average. This is different from the overall population average, from any simple difference between sire and dam phenotypes, or from a measure of variation like a standard deviation. The idea that the EPD reflects the expected progeny performance of a parent, expressed as a deviation from the mean, is what makes it a useful tool for selection.