DATA TERMS EXPLAINED
Charolais
Each EPD reported is accompanied with an Accuracy (ACC) value. ACC is a measure of reliability regarding the EPD evaluation for a performance trait. Accuracy is reported as a decimal number between zero and one: large values indicate greater accuracy and more certainty the EPD will show little change as additional progeny information is obtained. Birth Weight EPD (BW) The expected difference in average birth weight (pounds) of progeny. Birth weight reflects prenatal growth. Calving Ease Direct (CE) is expressed as a difference in percentage of unassisted births in first calf heifers. A higher value indicates greater calving ease. It predicts the average difference in unassisted births with which a sire's calves will be born when bred to first-calf heifers. Weaning Weight EPD (WW) The expected difference in average weaning weight of calves. The evaluation reflects the genetic influence on pre-weaning growth rate. Yearling Weight EPD (YW) The expected difference in average yearling weight of progeny. The evaluation reflects genetic influence on both pre-weaning and post-weaning growth rate. Maternal Milk EPD (Milk) The genetic ability of a sire’s or dam’s daughters to express in pounds of weaning weight in her calves due to her maternal ability through mothering instinct and milk. Total Maternal EPD (MTL) A value to predict the weaning weight performance of calves from a animal’s daughters due to genetics for growth and maternal ability. Total Maternal is calculated by adding ½ the WW EPD to the Maternal Milk EPD. Carcass records are adjusted to an age constant endpoint. Therefore selection based on any or all of the carcass merit EPD are comparable among cattle at the same age endpoint. For example selection based on increased EPD for carcass weight will result in heavier carcass weights than those animals with lower EPD for carcass weights when the cattle are harvested at the same age. Ribeye Area EPD (REA) Ribeye area is measured from a cross-sectional area of the longissimus dorsi muscle at the 12th rib. Ribeye area is a major component of the USDA yield grade equation and selection for increased ribeye area should result in larger ribeyes and lower yield grades between animals with the same carcass weight. Ribeye area has a positive relationship with weight, the larger the animal the larger the ribeye area. Ribeye Area EPD are expressed in square inches and is a predictor of differences in ribeye area between parents progeny at a constant age endpoint. Fat Thickness EPD (FAT) Fat thickness is measured at the 12th rib and is the primary component to the USDA Yield Grade equation. Fat thickness has a negative relationship to cutability; therefore, selection base on decreased fat thickness should result in lower yield grades and leaner cattle given the same age endpoint. Fat Thickness EPD are expressed in inches and are a predictor of differences in fat thickness between parent’s progeny at an age constant endpoint.
Marbling Score (MARB) Marbling is a subjective measure of the amount of intramuscular fat in the ribeye muscle. Marbling score is the primary component of USDA Quality grade and selection for increased Marbling Score EPD should result in cattle with higher quality grades at the same age endpoints. Marbling score has a small genetic correlation with fat, therefore producers may select for increased marbling score EPD while not changing external fat thickness when cattle are harvested at the same age-constant endpoint. Marbling EPD is a prediction of the differences in the USDA subjective marbling score between parent’s progeny at an age constant endpoint. Marbling is expressed in the same units as the USDA Marbling Score (see table below), see the accompanying table for USDA Marbling Score in the Carcass Section. Terminal Sire Index (TSI) The AICA Terminal Sire Index (TSI) is a formal method of combing Expected Progeny Differences (EPD) – BW, WW, YW, REA, CW, MARB and FAT – into one single value on which to base selec - tion decisions. The TSI uses estimates of the genetic relationships between traits with an economic default value based on three year rolling USDA data. The TSI represents a dollar index per terminal progeny produced for a bull in the AICA database, ranking them for profit potential. This dollar index is to be interpreted much like single trait EPD. For example, if Sire A’s index is $191.66 and Sire B’s index is $200.00, then we would expect Sire B’s offspring to average $8.34 more net return ($200.00 minus $191.66) than Sire A’s offspring. Heritabilities and Genetic Correlations Heritibility may be defined as the proportion of the observed phenotypic variation that is due to genetic variation. For example, when analyzing a group of Charolais calves from the same sire, one would expect some variation in the weaning weights. Since weaning weight is 25 percent heritable, 25 percent of the observed variation is attributable to genetics while the remaining 75 percent of the observed variation is due to environmental influences. Traits with low heritability estimates are influenced more by environment than by genetics, thus genetic progress from selection may be slow. Traits with low heritability respond greater to the effects of crossbreeding. Since heritability is already an integral part of the EPD calculation, EPD reflect actual differences and require no adjustment.
2025 CHAROLAIS NON-PARENT EPD AVERAGES
CE BW WW YW MILK MTNL REA FAT MARB TSI 11.4 -1.2 63.1 114 24.5 56.1 0.71 0.015 0.13 254.54
Red Angus
HB • HerdBuilder is a maternal selection index that predicts the economic differences of animals for traits that are important from conception through weaning. Expressed as dollars per head born, HB is calculated based on the scenario that bulls are matedto heifers and cows, replacement heifers are retained and all remaining progeny are marketed at weaning. Traits included in the HB index include Calving Ease Direct, Calving Ease Maternal, Weaning Weight, Milk, Mature Weight, Heifer Pregnancy and Stayability (Index/ High Value). GM • GridMaster is a selection index that predicts the average economic difference of non-replacement calves through the postweaning phase of production. GM places selection pressure on growth, feedyard performance and carcass traits. Expressed as dollars per head born, GM is calculated based on the sce - nario that progeny are fed out to slaughter and marketed on a quality-based carcass grid. Traits included in GM include Average Daily Gain, Carcass Weight, Dry Matter Intake, Marbling, Back Fat and Rib Eye Area (Index/High Value).
CED • Calving Ease Direct predicts differences in the percent of calves born unassisted out of 2-year-old dams. (Percent/High Value) BW • Birth Weight predicts differences in actual birth weight of progeny. (Pounds/Low Value) WW • Weaning Weight predicts differences in 205-day weaning weight. (Pounds/High Value) YW • Yearling Weight predicts differences in 365-day yearling weight. (Pounds/High Value) MILK • Milk predicts differences in weaning weight attributed to the milking ability of the animal’s daughters. (Pounds/High Value) STAY • Stayability predicts differences in the ability of an animals’ retained daughters to remain productive in the herd – calve every year – through 6 years of age. (Percent/High Value) MARB • Marbling predicts differences in marbling score – amount of intramuscular fat measured at the 13th rib. (Marbling Score Units/High Value) REA • Ribeye Area predicts differences in square inches of ribeye area measured at the 13th rib.(Square Inches/High Value)
2025 SPRING RED ANGUS NON-PARENT EPD AVERAGES
HB GM CED BW WW YW MILK REA MARB STAY 53 52 13 -1.8 65 104 26 0.16 0.45 14.6
4 WEST FORK RANCH
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