Glossary of Terms

EPD Terms and Abbreviations

Maternal EPDs

Calving Ease (CE): The average (%) difference of unassisted births from two-year old heifers. A higher value indicates greater calving ease.
(Excellent 14.0 to Low 2.0.)

Birth Weight (BW): Predicts the average difference in an animal's offspring at birth. The lower the number, the lighter the bull's calves will be. Used primarily for variance in WW that is due to milk.
(Excellent -3.1 to Low 4.1.)

Weaning Weight (WW): Predicts the average difference in an animal's offspring at weaning. The higher the number the more lbs at weaning. It does not account for variance in weaning weight that is due to milk.
(Excellent 49.7 to Low 18.1.)

Yearling Weight (YW): Predicts the average difference in an animal's progeny at one year of age. The higher the number the more lbs at yearling.
(Excellent 86.1 to Low 34.5.)

Maternal Calving Ease (MCE): Predicts calving ease of a bull's first-calving daughters compared to the daughters of a different sire.
(Excellent 9.1 to Low -1.9.)

Milk (MILK): Expressed as pounds of calf weaned. Reflect the average (%) difference due to the dam's milking ability. The dams would be the bull's daughters.
(Excellent 14.5 to Low -2.7.)

Maternal Weaning Weight (MWW): Expressed as pounds of calf weaned. Account for average differences from weaning weight direct and from the dam's milk. Also measures a sire's ability to transmit milk production and growth rate through his daughters.
(Excellent 32.8 to Low 11.0.)

Carcass EPDs

Carcass Weight (CW): Estimate average differences in carcass weight at a given age endpoint.
(Excellent 18.9 to Low -17.8.)

Yield Grade (YG): In an effort to apply the same scale the industry uses in qualifying meat yield the Percent Retail Cuts EPD is now expressed as an YG EPD. As with all EPDs, YG EPD is expressed as a deviation. Unlike its predecessor, negative values are desirable. To use it, keep in mind that it is in yield grade units. Therefore, lower is better. For example, a bull with a -.33 YG would be expected to sire offspring that are a 1/3 of a yield grade better (lower) than a 0.0 YG bull. If bulls with a zero EPD for Yield Grade sired an average of 3.0 in a particular environment and management system, offspring of a -0.33 bull would be expected to have an average yield grade of 2.67 (1/3 of a yield grade better/lower).
(Excellent -0.17 to Low 0.10.)

Marbling (MARB): The average difference in USDA Quality Grade in a bull's progeny at a given end point. A numerical marbling score where one point equals one USDA marbling score.
(Excellent 0.41 to Low -0.06.)

Back Fat (BF): Inches of carcass backfat at 475 days.
(Excellent -0.02 to Low 0.04.)

Ribeye Area (REA): The average difference in ribeye area in a bull's progeny at a given endpoint.
(Excellent 0.51 to Low -0.17.)

All-Purpose Index (API): Dollars per cow exposed under an all-purpose-sire scenario. Evaluates sires for use on the entire cow herd (bred to both Angus first-calf heifers and mature cows) with the portion of their daughters required to maintain herd size retained and the remaining heifers and steers put on feed and sold grade and yield.
(Excellent 136 to Low 78.)

Terminal Index (TI): Dollars per cow exposed under a terminal-sire scenario. Evaluates sires for use on mature Angus cows all offspring put on feed and sold grade and yield.
(Excellent 74 to Low 53.)

Using API and TI: First, determine which index to use; if you are keeping replacements use API, if not, use TI. Zero in on the difference between bulls. The difference can be used to determine how much a bull is worth compared to a different bull. Example: Bull 1 scores a +100 for API compared to Bull 2 with a score of +50. Bull one would be worth an extra $6000 over 4 years when exposed to 30 cows ($50 difference x 30 head x 4 years. = $6000).

Terms and Abbreviations for Actual Carcass Data

Hot Carcass Weight (HCW):

Avg. Daily Gain (ADG):

Ribeye Area (REA):

Back Fat (FT):

Carcass Yield Grade (CYG):

Ribeye/100 weight (REA/Cwt): (Based on 160)

Percent Retail Cuts (% RP)

Marbing Score (MBS):

Updated 2/04/2010