EPDs for Beef Cattle: A Glossary of Traits

If you are interested in beef cattle, one of the tools you will soon become familiar with is the EPD, or estimated progeny difference.

Perhaps you have already seen some EPDs in ads. Among the major selling points listed for a bull, you may have seen something like “WW +10,” for example. That is an EPD.

So what does it mean? And how is it useful?

Simply put, EPDs are for comparing the genetic value of different bulls of the same breed. If you understand the EPDs, you will have a general idea of the direction that a given sire will take your herd, genetically speaking.

Over the next few weeks, we’ll take a look at how to decipher EPDs, and then we’ll discuss the pros and cons of this breeding tool.

This week, we’ll start by examining some of the traits that EPDs seek to evaluate. Along the way, you’ll find out what the “WW” in “WW +10” means.

Notice that different breeds use different sets of EPDs, frequently geared toward mitigating the weaknesses and maximizing the profit potential of each breed. There are a few EPDs that are common to all or many breeds

The Four Standard EPDs

BW: Birth weight. Evaluates the birth weight of a sire’s progeny in pounds. This is a useful indicator of calving ease.
WW: Weaning weight. Evaluates the weight of a sire’s progeny at 205 days of age in pounds. This number is important to cow-calf producers because they sell calves by weight.
YW: Yearling weight. Evaluates the weight of a sire’s progeny at 365 days of age in pounds. This number is used to gauge how early a feeder calf will be ready for slaughter.
MM or Milk: Maternal milk. Evaluates the maternal ability of a sire’s daughters in pounds of calf, presumably directly related to milk production. This EPD is a little more controversial than some of the others. On the one hand, cows able to raise heavier calves can bring in more money from the sale barn. On the other hand, they tend to have higher maintenance costs.

Growth, Production, and Maternal Traits

CE or CED: Calving ease or calving ease direct. The ease with which a sire’s calves are born from first-calf heifers as a percentage of unassisted births. CE is used by Simmental producers, while CED is used by Angus, Charolais, Hereford, Limousin, and Red Angus producers. Gelbvieh producers sometimes use the two acronyms interchangeably.
CEM or MCE: Calving ease maternal. The ease with which a sire’s daughters will calve for the first time as a percentage of unassisted births. Used by Angus, Charolais, Gelbvieh, Limousin, and Simmental producers.
CETM: Calving ease total maternal. The probability of a sire’s daughter calving without assistance as a percent. Used by Hereford and Red Angus producers.
DOC: Docility. An estimate of a sire’s ability to produce docile progeny. Used by Angus, Charolais, Limousin, Maine Anjou, and Salers producers.
M&G, TM, or MWW: Milk and growth, total maternal, or maternal weaning weight. A formula for estimating a sire’s ability to transmit growth and milk production to his daughters. 1/2 WW + MM = M&G. Widely used, but the acronym varies by breed.
MW or MCW: Mature weight. An evaluation of the mature weight of a sire’s daughters in pounds. Used by Angus and Hereford producers.
SC or SCR: Scrotal circumference. A prediction of scrotal circumference in centimeters. This measurement is significant because a larger scrotal circumference typically corresponds to earlier puberty and better semen quality. Used by Angus, Beefmaster, Brangus, Charolais, Gelbvieh, Hereford, and Limousin producers.
ST or Stay: Stayability. The probability that a sire’s daughters will remain in the herd for a set period of time (usually six years), expressed as a percent. This is an indication of longevity and reproductive ability, since nonproductive cows are usually culled. Used by Gelbvieh, Limousin, Red Angus, and Simmental producers.

Angus and Red Angus

HPG: Heifer pregnancy. The probability of a sire’s daughters becoming pregnant during the first breeding season as a percent. Used by Angus and Red Angus producers.
ME: Maintenance energy. An estimate of the energy a sire’s daughters spend on body maintenance in megacalories per month. Used by Red Angus producers.
MH: Mature height. An evaluation of the mature height of a sire’s daughters in inches. Used by Angus producers.
RADG: Residual average daily gain. An estimate of a sire’s ability to transmit weight gain to his offspring in pounds per day. Used by Angus producers.
YH: Yearling height. An estimate of a sire’s ability to transmit height to his offspring in inches. Used by Angus producers.

Gelbvieh

GL: Gestation length. An evaluation of the gestation length of a sire’s progeny in days. Shorter gestation lengths appear to be linked to greater calving ease. Used by Gelbvieh producers.

Hereford

TEAT: Teat size. An estimate of a sire’s contribution to the teat size of his daughters based on a 9-point scale. Teat size affects the ability of a calf to nurse easily. Used by Hereford producers.
UDDR: Udder suspension. An estimate of a sire’s ability to transmit sound udders to his daughters based on a 9-point scale. Used by Hereford producers.

Carcass Traits

CW: Carcass weight. An evaluation of the carcass weight of a sire’s progeny immediately prior to chilling in pounds. Used by Angus, Brahman, Brangus, Charolais, Gelbvieh, Hereford, Limousin, Red Angus, Simbrah, and Simmental producers.
Fat: Fat thickness. A prediction of the backfat thickness over the ribeye between the 12th and 13th ribs in a sire’s progeny in inches, as detected by ultrasound. As backfat increases, percent retail product decreases. Used by Angus, Brahman, Brangus, Charolais, Gelbvieh, Red Angus, Simbrah, and Simmental producers.
IMF: Intramuscular fat. An estimate of a sire’s ability to transmit intramuscular fat between the 12th and 13th ribs to his progeny as a percentage of fat compared to muscle, as detected by ultrasound. Used by Angus, Hereford, and Limousin producers.
MB or Marb: Marbling. An estimate of a sire’s ability to transmit marbling to his progeny based on the USDA scoring system, as detected by ultrasound. This trait is significant because increased marbling earns higher scores and therefore higher prices. Used by Angus, Brahman, Brangus, Charolais, Gelbvieh, Limousin, Red Angus, Simbrah, and Simmental producers.
REA or RE: Ribeye area. An estimate of the ribeye area of a sire’s progeny in square inches, as detected by ultrasound. This trait is useful in predicting carcass weight and percent retail product. Used by Angus, Brahman, Brangus, Charolais, Gelbvieh, Limousin, Red Angus, Simbrah, and Simmental producers.
SHR: Shear force. An estimate of the force needed to cut the meat of a sire’s progeny in pounds. Shear force is a good indicator of meat tenderness. Used by Brahman and Simmental producers.
YG: Yield grade. An estimate of the yield of salable beef of a sire’s progeny based on a yield grade scoring system. Used by Limousin, Simbrah, and Simmental producers.

Brahman

%RP: Percent retail product. An estimate of the yield of salable beef relative to waste products of a sire’s progeny expressed as a percent. Used by Brahman producers.

Profit ($) Indexes

All profit indexes are calculated in dollars per head unless otherwise noted.

$F or FM: Feedlot value. An evaluation of the revenue and cost of a sire’s progeny after weaning. Used by Angus and Gelbvieh producers.
$G or CV: Grid value or carcass value. An evaluation of the economic advantage of a sire’s progeny based on USDA quality and yield grading systems. Used by Angus and Gelbvieh producers.
API: All-purpose index. An evaluation of the economic performance of a Simmental sire’s progeny from Angus cows using a model where some of the progeny are kept for breeding and some are sent to the feedlot. Used by SimAngus and Simmental producers.
TI: Terminal index. An evaluation of the economic performance of a Simmental sire’s progeny from Angus cows when all of the offspring are sent to the feedlot. Used by SimAngus and Simmental producers.

Angus and Red Angus

$B: Beef value. An estimate of the revenue and costs of a sire’s progeny based on both postweaning performance and carcass merit. Used by Angus producers.
$EN: Cow energy value. A gauge of the input requirements of a sire’s daughters in dollar savings per cow per year. Used by Angus producers.
$QG: Quality grade. An evaluation of the economic advantage of a sire’s progeny based on USDA quality grade, which is in turn based primarily on marbling. Used by Angus producers.
$W: Weaned calf value. An evaluation of both the revenue and the cost of a sire’s progeny up to weaning based on birth weight, growth, maternal milk, and mature size. Used by Angus producers.
$YG: Yield grade. An evaluation of the economic advantage of a sire’s progeny based on red meat yield grade. Used by Angus producers.

Hereford

BII$: Brahman influence index. An evaluation of the economic performance of a Hereford sire’s Brahman-cross progeny when marketed through conventional channels. This EPD was designed specifically for Southerners who need to include Brahmans in their breeding programs for heat tolerance, but who do not want to lose meat quality. Used by Hereford producers.
BMI$:Baldy maternal index. An evaluation of the economic performance of a Hereford sire’s Angus-cross progeny when marketed through the Certified Hereford Beef program. Used by Hereford producers.
CHB$: Certified Hereford Beef index. An evaluation of the economic performance of a Hereford sire’s crossbred progeny when marketed through the Certified Hereford Beef program. This is a method of combining growth and carcass traits. Used by Hereford producers.
CEZ$: Calving ease index. An evaluation of the economic performance of a Hereford sire’s progeny born to first-calf heifers when marketed through the Certified Hereford Beef program. Only figuring first-calf heifers into the equation emphasizes calving ease, since these heifers are the most likely animals to have calving difficulties. Used by Hereford producers.

Limousin

$MTI: Mainstream terminal index. An evaluation of the economic performance of a Limousin sire’s progeny born to British-cross cows when marketed through conventional channels. Used by Limousin producers.

Now that you have a glossary to work with, you’re ready to start learning how to use EPDs.

Next week: Crunching the Numbers