An EPD (expected progeny difference) predicts how an animal's calves will compare with the calves of an average animal of the same breed. EPDs are worked out from the records players create in the game: every birth weight, the calf's sex, its sire and dam, and the cow that carried it. Nothing hidden is used.
Birth weight (BW)
The BW EPD is in pounds. A bull at -2.0 is expected to sire calves 2 lb lighter at birth than a bull at 0.0 when both are bred to the same cows. Zero is the average foundation animal of the breed, so a breed's average can drift up or down as breeders select.
Accuracy (ACC)
Accuracy runs from 0 to 1 and says how much information stands behind the number. A young animal gets its EPD from its pedigree and its own birth weight, so its accuracy is low and its EPD can move. A sire with many recorded calves has a high accuracy and an EPD that will barely change. An animal with almost nothing known shows a dash.
Rank
The rank compares the animal with the active registered cattle of its breed. Top 10% for birth weight means only one animal in ten has a lower BW EPD.
Who gets EPDs
- Only registered cattle. An animal with papers in two registries has an EPD in each, and the two are not on the same scale.
- EPDs are breed by breed. An Angus +1.0 and a Maine-Anjou +1.0 are not the same calf weight; compare animals within a registry.
- A registry starts getting EPDs once 100 of its registered cattle were born in the game with a recorded birth weight and a known sire and dam.
- Starter cattle have no parents on record. A starter begins at the breed average with no accuracy and earns its EPD through its calves.
When they change
Every registry is re-evaluated each Sunday. An animal registered during the week gets an EPD straight away, marked interim if it has not been through a Sunday evaluation yet.