Expected Progeny Differences - (EPD’s
CALVING EASE DIRECT (CED) is the difference in percentage of unassisted births when a sire is bred to first-calf heifers when compared to progeny of other sires. A higher number is desirable. BIRTH WEIGHT (BW) is reported in pounds as the difference in average birth weight of progeny compared to that of other sires. WEANING WEIGHT (WW) is reported in pounds and predicts the difference in weight of progeny averaged at 205- days of age to calves of other sires. YEARLING WEIGHT (YW) is reported in pounds and predicts the difference in weight of progeny averaged at 365- days of age to calves of other sires. MILK (M) predicts the sire’s genetic merit for milking ability as expressed in his daughters compared to daughters of other sires. Milk accounts for the part of a calf’s weaning weight attributed to milking ability of the dam. TOTAL MATERNAL (TM) is reported in pounds as a reflection of a sire’s daughters milking ability and growth poten- tial of their calves when compared to other sire’s daughters. It is equal to the Milk EPD plus one half of the WW EPD. CALVING EASE MATERNAL (CEM) is the difference in percentage of unassisted births of a sire’s daughters as first- calf heifers when compared to daughters of other sires. A higher number is desirable. SCROTAL CIRCUMFERENCE (SC) is reported in centimeters and predicts the difference in yearling scrotal circum- ference of a bull’s male progeny compared to sons of other sires. U.S. RIBEYE AREA (REA) is reported in square inches as the prediction of difference in square inch ribeye area of a bull’s beef bound progeny compared to progeny of other sires. U.S. FAT THICKNESS (FT) is reported in inches as the prediction in difference of fat thickness on a carcass when mea- sured between the 12th and 13th ribs of a bull’s beef bound progeny compared to progeny of other sires. U.S. INTRAMUSCULAR FAT (IMF) is reported in decimal terms representing percentage of intra-muscular fat, which is highly correlated with USDA marbling score, a major determinant of USDA quality grade. As with all EPDs, the ab- solute value has no inherent relevance, but is used to compare one sire to another. HEIFER PREGNANCY (HP) is reported in percentile units and represents the probability of a sire’s daughters becom- ing pregnant during their first breeding season compared to daughters of other sires. STAYABILITY (STAY) is reported in percentile units and represents the probability that a cow will have five consecu- tive calves compared to her yearling contemporaries. MATURE COW WEIGHT (MCW), expressed in pounds, is a predictor of the difference in mature cow weight of a sire’s daughters when compared to daughters of other sires. TERMINAL INDEX (TI) is a bio-economic index which considers six growth and carcass-related traits, each trait weighted according to its heritability and economic importance in a feedlot situation with carcasses valued by weight, yield, and quality grade. The value is expressed in standard deviation terms, which can be difficult to com- prehend. IBBA advises breeders to evaluate the percentile rank rather than the actual index value.
Genetic Partners | Page 7
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