Genetic estimates for milk production for beef bulls are usually cited as Milk EPDs or Maternal Milk EPDs. EPD is the acronym for expected progeny difference or a measure of the transmitted genetic effect of a sire or dam. Obviously, beef cows are not milked, so there is no direct measure of milk production. However, because a major share of weaning weight is due to milk production, weaning weight differences can be used to estimate the "pounds of weaning weight due to milk." Thus, milk EPDs estimate the pounds of weaning weight due to milk, not the pounds of milk produced by a bull's daughters. When a bull is 4 1/2 years old his daughters wean their first calves, and the milk EPD can be estimated with some degree of accuracy. The "direct" genetic effect of a bull on weight of his progeny can be separated from his "maternal" genetic effect on the weight of his grand-progeny (through his daughter's milk). Thanks to large, sophisticated computers, this separation of the direct and maternal effects allows for reasonably accurate estimates of milking ability. These estimates are much more accurate in older bulls that have daughters in production, but Milk EPDs can be made from pedigree estimation for yearling bulls (and yearling heifers). All the major beef breeds publish EPDs for Milk or Maternal Milk in their sire evaluation reports.

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