At the begining of each year, the American Gelbvieh Association releases their updated guide to EPD’s. Below you will find this information from their website, www.gelbvieh.org.
Guide to the American Gelbvieh Association Expected Progeny Differences (EPDs)
Expected progeny differences (EPDs) can be used to predict the average performance of a bull’s offspring compared to other calves in their contemporary group (a contemporary group being calves that were born in the same calving season, in the same year, herd, sex, and were managed similarly). EPDs are measured in the units of the trait, and show the differences in performance between animals. For example, if Bull A has a weaning weight EPD of 80, and Bull B in the same herd has a weaning weight EPD of 70, then bull A’s calves would be expected to be 10 pounds heavier at weaning than those of bull B.
It is important to remember that this number is just a prediction of performance. Actual performance depends on many factors such as environment, management, etc. This being said, an EPD is by far the most reliable indicator of an animal’s genetic merit due to the amount of information incorporated into the calculation.
The American Gelbvieh Association uses all available information to predict an animal’s EPD. This information includes: individual performance, pedigree, progeny and grand progeny performance, plus available genomic information. All this information is combined into one easy to use number for selected traits that helps breeders make genetic improvement in their herd.
In an EPD listing, an accuracy number is often published below its corresponding EPD. Accuracy is defined as the strength of the relationship between a prediction (EPD) and a sire’s true genetic value. In other words, accuracy is an indicator of the reliability of an EPD. Accuracy is improved by the number of records reported for an animal and with genomic information. For example, a three year old bull with 90 calves would have EPDs of higher accuracy than a virgin yearling bull. Accuracies range from zero to one, with numbers closer to one being more accurate.
Listed below are the definitions of American Gelbvieh Association EPDs and the units in which they are published. The EPDs with an asterisk (*) next to the name are available to members only.
Calving ease direct (CED): Percent of unassisted births of a bull’s calves when he is used on heifers. A higher number is favorable, meaning better calving ease. This EPD can be vital to a rancher looking to decrease the amount of calves pulled in his herd.
Milk (Milk): The genetic ability of a sire’s daughters to produce milk expressed in pounds of weaning weight.
Calving ease maternal (CEM): Represented as percent of unassisted births in a sire’s first-calving daughters. A higher number represents more favorable calving ease. This EPD is important to a rancher’s bottom line because it predicts which animals produce daughters with a genetic pre-disposition to calve unassisted as heifers.
Heifer pregnancy (HP): Predicts the probability that a bull’s daughters will become pregnant as first-calf heifers in a regular breeding season, expressed as a percent. A higher value of this EPD is favorable, meaning that a higher percentage of a sire’s daughters get pregnant as first calf heifers compared to other sires in his contemporary group.
30-month pregnancy (Pg30): Predicts the probability that a bull’s daughters will become pregnant and calve at three years of age, given that they calved as first-calf heifers. This EPD is expressed as a percent, again, with a higher number being more favorable meaning a higher percentage of a sire’s daughters will calve at three years of age, given they calved as first-calf heifers.
Stayability (ST): Predicts the genetic difference, in terms of percent probability, that a bull’s daughters will stay productive within a herd to at least six year of age. The stayability EPD is one of the best measures currently available to compare a bull’s ability to produce females with reproductive longevity.
Birth weight (BW): Predicts the difference, in pounds, for birth weight of the calf.
Weaning weight (WW): Predicts the difference, in pounds, for weaning weight (adjusted to age of dam and a standard 205 days of age). This is an indicator of growth from birth to weaning.
Yearling weight (YW): Predicts the expected difference, in pounds, for yearling weight (adjusted to a standard 365 days of age). This is an indicator of growth from birth to yearling.
*Mature weight EPD (MW): Predicts the average difference in pounds of mature weight of a sire’s progeny compared to their contemporaries.
Yield grade (YG): Differences in yield grade score, which is a predictor of percent retail product. Smaller values suggest that progeny will have a better lean to fat ratio.
Carcass weight (CW): Differences in pounds of hot carcass weight, adjusted to an industry standard age endpoint.
Ribeye area (REA): Differences in ribeye area in inches between the 12th and 13th rib. Greater ribeye areas are preferable.
Marbling (MB): Predicts the differences in the degree of marbling within the ribeye as expressed in marbling score units. Greater marbling numbers are preferable and are an indicator of higher carcass quality grades.
Fat (FT): Differences for fat thickness, in inches, for a carcass over the 12th rib, smaller numbers of fat thickness are preferable as excess fat can be detrimental to yield grade.
Dry matter intake (DMI): Represents the average daily dry matter intake per day consumed in pounds. A negative, or lesser value, is more favorable. For example, Bull A has a DMI EPD of .15 and Bull B has a DMI EPD of -.20, so the progeny of Bull B consume, on average, .35 pound less dry matter per day than progeny from Bull A.
*Average daily gain (ADG): Difference in average daily gain in pounds based on an animal’s performance during a feed intake test period.
*Residual feed intake (RFI): Defined as the difference between an animal’s actual daily feed intake and its predicted daily intake based on growth rate and body size. Animals with a positive RFI value are deemed more inefficient because they consume more than expected while animals with a negative RFI value are considered more efficient because they consume less than expected.
Indexes are tools that allow producers to select for several EPDs at once, making selections more efficient than selecting on one trait at a time. Indexes weigh traits based on their importance to a producer’s bottom line by using a trait’s economic and genetic value. Indexes are a good way to put selection emphasis on traits that are economically relevant.
Total maternal (TM): An index that combines growth and milk information as a prediction of the weaning weight performance of calves from a sire’s daughters. As an index, this value is not reported with an accompanying accuracy. A greater TM value means a mother that returns comparatively higher weaning weights on her calves. TM Index = MK EPD + ½ WW EPD.
$Cow: Represents the genetic value in dollars of profit of an animal when retained as a replacement female relative to other animals in the herd. A higher number represents more profitable genetics for maternal productivity. $Cow will serve producers in selecting bulls that will sire daughters with stayability and reproductive efficiency as well as other traits that lead to profitability in a production system, such as milk, calving ease, moderate mature weight and the ability of calves to gain. A female’s genetics also influence the performance of her calves in the feedlot and at slaughter, so traits such as feed efficiency and carcass value are also included in $Cow.
Efficiency profit index (EPI): An economic selection index developed to aid producers in selecting for more feed efficient cattle that still have acceptable amounts of gain. The EPI provides slight negative pressure on intake, while keeping gain at a constant value. By selecting on this index, producers will be able to find those animals that gain the same amount as their contemporaries while eating less.
FPI: An economic selection index designed to aid producers in selecting sires whose progeny will perform in the feedlot and are sold on a grade and yield standpoint. Well ranking sires for FPI have higher marbling and carcass weight than their contemporaries. As a terminal index, little emphasis is put on maternal traits such as stayability and calving ease.