American Angus Association Selection Tools
Maternal EPDs Heifer Pregnancy (HP) , is a selec- tion tool to increase the probability or chance of a sire’s daughters be- coming pregnant as first-calf heifers during a normal breeding season. A higher EPD is the more favorable direction and the EPD is reported in percentage units. Calving Ease Maternal (CEM) , is expressed as a difference in per- centage of unassisted births with a higher value indicating greater calving ease in first-calf daughters. It predicts the average ease with which a sire’s daughters will calve as first-calf heifers when compared to daughters of other sires. Maternal Milk EPD (Milk) , is a predictor of a sire’s genetic merit for milk and mothering ability as expressed in his daughters com- pared to daughters of other sires. In other words, it is that part of a calf’s weaning weight attributed to milk and mothering ability. Teat Size EPD (Teat) , expressed in units of teat size score, with a higher EPD indicating a sire will produce daughters with smaller teat size compared to that of other sires’ daughters. Udder Suspension EPD (UDDR) , expressed in units of udder suspen- sion score, with a higher EPD indi- cating a sire will produce daughters with tighter udder suspension compared to that of other sires’ daughters. Functional Longevity EPD (FL) , expressed in number of calves, is a predictor of the number of calves a sire’s daughters are predicted to produce by 6 years of age com- pared to that of other sires’ daugh- ters. A higher EPD is the more favorable direction indicating more calves produced on average.
Management EPDs Docility EPD (Doc) , is expressed as a difference in yearling cattle temperament, with a higher value indicating more favorable docility. It predicts the average difference of progeny from a sire in comparison with another sire’s calves. In herds where temperament problems are not an issue, this expected differ- ence would not be realized. Claw Set EPD (Claw) , is expressed in units of claw-set score, with a lower EPD being more favorable in- dicating a sire will produce progeny with more ideal claw set. The ideal claw set is toes that are symmetri- cal, even and appropriately spaced. Foot Angle EPD (Angle) , is ex- pressed in units of foot-angle score, with a lower EPD being more favor- able indicating a sire will produce progeny with more ideal foot angle. The ideal is a 45-degree angle at the pastern joint with appropriate toe length and heel depth. Carcass EPDs Carcass Weight EPD (CW) , ex- pressed in pounds is a predictor of the differences in hot carcass weight of a sire’s progeny com- pared to progeny of other sires. Marbling EPD (Marb) , expressed as a fraction of the difference in USDA marbling score of a sire’s progeny compared to progeny of other sires. Ribeye Area EPD (RE) , expressed in square inches, is a predictor of the difference in ribeye area of a sire’s progeny compared to progeny of other sires. Fat Thickness EPD (Fat) , expressed in inches, is a predictor of the dif- ferences in external fat thickness at the 12th rib (as measured between the 12th and 13th ribs) of a sire’s progeny compared to progeny of other sires.
Expected Progeny Difference (EPD) An EPD is the prediction of how future progeny are expected to perform relative to progeny of other animals within the same database. EPDs are expressed in units of mea- sure for the trait, plus or minus. Production EPDs Calving Ease Direct (CED ), is expressed as a difference in per- centage of unassisted births, with a higher value indicating greater calving ease in first-calf heifers. It predicts the average difference in ease with which a sire’s calves will be born when he is bred to first-calf heifers. Birth Weight EPD (BW) , expressed in pounds, is a predictor of a sire’s ability to transmit birth weight to his progeny compared to that of other sires. Weaning Weight EPD (WW) , ex- pressed in pounds, is a predictor of a sire’s ability to transmit weaning growth to his progeny compared to that of other sires. Yearling Weight EPD (YW) , ex- pressed in pounds, is a predictor of a sire’s ability to transmit yearling growth to his progeny compared to that of other sires. Residual Average Daily Gain (RADG) , expressed in pounds per day, is a predictor of a sire’s genetic ability for postweaning gain in future progeny compared to that of other sires, given a constant amount of feed consumed. Scrotal Circumference EPD (SC) , ex- pressed in centimeters, is a predic- tor of the difference in transmitting ability for scrotal size compared to that of other sires.
2
Made with FlippingBook - Share PDF online