Have you ever wondered what all those numbers and ratings mean when folks get together to talk bulls? Expected Progeny Difference and Value Index in Angus Bulls explained. The definitions below are from the American Angus Association.
Expected Progeny Difference (EPD) , is the prediction of how future progeny of each animal are expected to perform relative to the progeny of other animals listed in the database. EPDs are expressed in units of measure for the trait, plus or minus. Interim EPDs may appear on young animals when their performance has yet to be incorporated into the American Angus Association National Cattle Evaluation (NCE) procedures. This EPD will be preceded by an “I”, and may or may not include the animal’s own performance record for a particular trait, depending on its availability, appropriate contemporary grouping, or data edits needed for NCE.
EPDs are enhanced by genomic results generated by:
$Value Index ($Value), an economic selection index allows multiple change in several different traits at once pertaining to a specific breeding objective. The $Value is an estimate of how future progeny of each sire are expected to perform, on average, compared to progeny of other sires if the sires were randomly mated to cows and if calves were exposed to the same environment.
Accuracy (ACC), is the reliability that can be placed on the EPD. An accuracy of close to 1.0 indicates higher reliability. Accuracy is impacted by the number of progeny and ancestral records included in the analysis.
PRODUCTION EPDs
Calving Ease Direct (CED), is expressed as a difference in percentage 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), expressed 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), expressed 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 post weaning gain in future progeny compared to that of other sires, given a constant amount of feed consumed.
Dry Matter Intake (DMI), expressed in pounds per day, is a predictor of difference transmitting ability for feed intake during the post weaning phase, compared to that of other sires.
Yearling Height EPD (YH), is a predictor of a sire’s ability to transmit yearling height, expressed in inches, compared to that of other sires.
Scrotal Circumference EPD (SC), expressed in centimeters, is a predictor of the difference in transmitting ability for scrotal size compared to that of other sires.
Docility (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 difference would not be realized.
MATERNAL EPDs
Heifer Pregnancy (HP), is a selection tool to increase the probability or chance of a sire’s daughters becoming 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 percentage 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 compared to daughters of other sires. In other words, it is that part of a calf’s weaning weight attributed to milk and mothering ability.
Herds (MkH) indicate the number of herds from which daughters are reported.
Daughters (MkD) reflects the number of daughters that have progeny weaning weight records included in the analysis.
Mature Weight EPD (MW), expressed in pounds, is a predictor of the difference in mature weight of daughters of a sire compared to the daughters of other sires.
Mature Height EPD (MH),expressed in inches, is a predictor of the difference in mature height of a sire’s daughters compared to daughters of other sires.
Cow Energy Value ($EN), expressed in dollar savings per cow per year, assesses differences in cow energy requirements as an expected dollar savings difference in daughters of sires. A larger value is more favorable when comparing two animals (more dollars saved on feed energy expenses). Components for computing the cow $EN savings difference include lactation energy requirements and energy costs associated with differences in mature cow size.
CARCASS EPDs
Carcass Weight EPD (CW), expressed in pounds is a predictor of the differences in hot carcass weight of a sire’s progeny compared 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 differences 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.
Group/progeny (C Grp/ Pg and U Grp/Pg) reflects the number of contemporary groups and the number of carcass and ultrasound progeny included in the analysis.
FOOT SCORE EPDs
Claw Set EPD (Claw), is expressed in units of claw-set score, with a lower EPD being more favorable indicating a sire will produce progeny with more ideal claw set. The ideal claw set is toes that are symmetrical, even and appropriately spaced.
Foot Angle EPD (Angle), is expressed in units of foot-angle score, with a lower EPD being more favorable 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.
PAP EPDs
$VALUE INDEXES
$Value indexes, an economic selection index allows multiple change in several different traits at once pertaining to a specific breeding objective. The $Value is an estimate of how future progeny of each sire are expected to perform, on average, compared to progeny of other sires if the sires were randomly mated to cows and if calves were exposed to the same environment.
Maternal Weaned Calf Value ($M) , an index, expressed in dollars per head, predicts profitability differences from conception to weaning with the underlying breeding objective assuming that individuals retain their own replacement females within herd and sell the rest of the cull female and all male progeny as feeder calves. The model assumes commercial producers will replace 25% of their breeding females in the first generation and 20% of their breeding females in each subsequent generation. Traits included are as follows: calving ease direct, calving ease maternal, weaning weight, milk, heifer pregnancy, docility, mature cow weight, claw set and foot angle.
Weaned Calf Value ($W), an index, expressed in dollars per head, to predict profitability differences in progeny due to genetics from birth to weaning. The underlying objective being producers will retain 20% of the female progeny as replacements and sell the rest of the cull females and their male counterparts as feeder calves. Traits included are as follows (in no particular order): birth weight, weaning weight, milk, and mature cow weight.
Feedlot Value ($F), an index, expressed in dollars per head, to predict profitability differences in progeny due to genetics for post weaning feedlot merit compared to the progeny of other sires. The underlying objective assumes producers will retain ownership of cattle through the feedlot phase and sell fed cattle on a carcass weight basis, but with no consideration of premiums or discounts for quality and yield grade. Traits contributing directly to the index are as follows: yearling weight (gain), carcass weight and feed efficiency.
Grid Value ($G), an index, expressed in dollars per carcass, to predict profitability differences in progeny due to genetics for carcass grid merit compared to progeny of other sires. The underlying objective assumes producers will market cattle on an above-industry-average carcass grid. Traits included in the index are as follows (in no particular order): carcass weight, marbling, ribeye area, and fat.
Beef Value ($B), a terminal index, expressed in dollars per carcass, to predict profitability differences in progeny due to genetics for post weaning and carcass traits. This terminal index assumes commercial producers wean all male and female progeny, retain ownership of these animals through the feedlot phase and market these animals on a carcass grid. Traits included in the index are as follows: yearling weight, dry-matter intake, marbling, carcass weight, ribeye area and fat.