Quick Reference to ASA EPDS and Indexes
Expected Progeny Differences (EPDS): EPD ’ s are the most accurate and effecti v e tool a v ailable for comparing genetic le v els . In using EPD , the difference bet w een t w o sires ’ EPD represents the unit difference e x pected in the performance of their progen y . For e x ample , if sires A and B ha v e EPD of + 10 and – 5 , a 15 - unit difference w ould be e x pected in their progen y ( mo v ing from - 5 to + 10 y ields 15 units ). Ke y to using EPD is kno w ing w hat units the y are e x pressed in . For e x ample , if the abo v e case referred to w eaning w eight EPD , A w ould be e x pected to sire 15 - pounds more w eaning w eight than B . If cal v ing ease w ere the trait , A w ould be e x pected to sire 15 - percent more unassisted births in first - calf heifers ; in other w ords , if B sired 30 assists in a group of 100 heifers , w e ’ d e x pect A to require 15 assists . A percentile - ranking chart is required to determine w here a bull ’ s EPD rank him relati v e to other bulls in the breed . For percentile rankings or more detailed information about EPD ’ S and inde x es v isit www . simmental . org . EPD’s are the most accurate and effective tool available for comparing genetic levels. In using EPD, the difference between two sires’ EPD represents the unit difference expected in the performance of their progeny. For example, if sires A and B have EPD of +10 and –5, a 15-unit difference would be expected in their progeny (moving from -5 to +10 yields 15 units). Key to using EPD is knowing what units they are expressed in. For example, if the above case referred to weaning weight EPD, A would be expected to sire 15-pounds more weaning weight than B. If calving ease were the trait, A would be expected to sire 15- percent more unassisted births in first-calf heifers; in other words, if B sired 30 assists in a group of 100 heifers, we’d expect A to require 15 assists. A percentile-ranking chart is required to determine where a bull’s EPD rank him relative to other bulls in the breed. For percentile rankings or more detailed information about EPD’S and indexes visit www.simmental.org.
ASA EPD Definitions
All - Purpose Inde x ( API ): Dollars per co w e x posed under an all - purpose - sire scenario . All-Purpose Index (API): Dollars per cow exposed under an all-purpose-sire scenario. Back Fat (BF): Inches of backfat. Birth Weight (BW): Pounds of birth weight. Calving Ease (CE): Percent of unassisted births when used on heifers. Maternal Calving Ease (MCE): Percent of unassisted births in first-calving daughters. Milk (MLK): Pounds of weaning weight due to milk. Marbling (MRB): Marbling score. Ribeye Area (REA): Square inches of ribeye. Warner-Bratzler Shear Force (WBSF): Pounds of force required to shear a steak. Back Fat ( BF ): Inches of backfat . Birth Weight ( BW ): Pounds of birth w eight . Cal v ing Ease ( CE ): Percent of unassisted births w hen used on heifers . Maternal Cal v ing Ease ( MCE ): Percent of unassisted births in first - cal v ing daughters . Milk ( MLK ): Pounds of w eaning w eight due to milk . Marbling ( MRB ): Marbling score . Ribe y e Area ( REA ): Square inches of ribe y e . Warner - Brat z ler Shear Force ( WBSF ): Pounds of force required to shear a steak . Sta y abilit y ( STAY ): Percent of daughters remaining in the co w herd at 6 y ears of age . Stayability (STAY): Percent of daughters remaining in the cowherd at 6 years of age. Terminal Index (TI): Dollars per cow exposed under a terminal-sire scenario. (See below for more details.) Terminal Inde x ( TI ): Dollars per co w e x posed under a terminal - sire scenario . ( See belo w for more details .)
Weaning Weight ( WW ): Pounds of w eaning w eight . Weaning Weight (WW): Pounds of weaning weight. Yearling Weight (YW): Pounds of yearling weight. Yield Grade (YG): Yield grade score. Yearling Weight ( YW ): Pounds of y earling w eight . Yield Grade ( YG ): Yield grade score .
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