by Larry Kuehn, Bailey Engle and Warren Snelling, USMARC

National cattle evaluation (NCE) and the resulting expected progeny differences (EPDs) have resulted in substantial genetic change since their inception in the 1970s. However, because of differences in the genetic bases, EPDs are generally only comparable within breed.

Since 1993, the U.S. Meat Animal Research Center (USMARC) has produced a table of factors to adjust the within-breed EPDs of cattle so that the merit of individuals can be compared across breeds. Adjustment factors for carcass traits have been calculated since 2009, and carcass weight was added in 2015. To be included, breeds must have carcass data in the USMARC database and report their carcass EPDs on an actual carcass basis using an age-adjusted end point.

Bulls of different breeds can be compared on the same EPD scale by adding the appropriate adjustment factor to the EPDs produced in the most recent genetic evaluations for each of the 18 breeds.

Normally, the EPDs of animals from different breeds cannot be compared because many breed associations compute their EPDs in separate analyses, and each breed has a different base point. The across-breed adjustment factors allow producers to compare the EPDs for animals from different breeds for these traits; these factors reflect both the current breed difference (for animals born in 2024) and differences in the breed base point.

The across-breed EPDs (AB-EPDs) are most useful to commercial producers purchasing bulls of more than one breed to use in crossbreeding programs. For example, in terminal crossbreeding systems, AB-EPDs can identify bulls in different breeds with similar growth potential or favorable carcass characteristics.

The factors are derived by estimating breed differences from the USMARC germplasm evaluation program and adjusting these differences for the EPDs of the sires that were sampled in the system. Traits for which factors are estimated are birth weight (BW), weaning weight (WW), yearling weight (YW), maternal weaning weight (Milk), marbling score (Marb), ribeye area (RE), backfat depth (Fat) and carcass weight (CW) (see Table 1). The factors adjust the EPDs to an Angus base.

As an example, suppose a Red Angus bull has a CW EPD of + 20.0 pounds (lb.), a Hereford bull has a CW EPD of + 72.0 lb., and an Angus bull has a CW EPD of 52 lb. The across-breed adjustment factors for carcass weight (see Table 1) are -3.8 lb. for Red Angus, -68.2 lb. for Hereford and 0.0 for Angus. We adjust accordingly to get the AB-EPDs.

When mated to cows of another breed (Braunvieh, for example), the Red Angus bull in the example would be expected to sire calves with carcasses averaging 12.4 lb. heavier (16.2 – 3.8 = 12.4) than progeny of the Hereford bull and 35.8 lb. lighter than progeny of the Angus bull.

Brahman EPDs for marbling score are reported on a different scale than the other breeds with marbling score EPDs. For Brahman 300 = Sl⁰⁰ and 400 = Sm⁰⁰; whereas, for the other breeds, 4.00 = Sl⁰⁰ and 5.00 = Sm⁰⁰, meaning the Brahman EPDs are reported on a scale that is 100 times larger in magnitude in addition to a base shift. As a result, EPDs from other breeds need to be multiplied by 100 after being adjusted to Brahman, and Brahman EPDs need to be divided by 100 prior to applying the adjustment factors.

For instance, to adjust a Simmental bull with a marbling score EPD of 0.15 to compare to Brahman bulls using the factors from Table 1, add the Simmental factor, subtract the Brahman factor, and then multiply by 100: [0.15 + (-0.15) – (-0.67)] * 100 = 67. Similarly, to adjust a Brahman bull with a marbling score EPD of 40 to compare to Simmental bulls using the same factors, first divide by 100, then add the Brahman factor, and subtract the Simmental factor: 40 ÷ 100 + (-0.67) – (-0.15) = -0.12.

Please note that as of 2024, yearling weight EPD adjustment factors are derived using a BIF adjusted postweaning gain and weaning weight as separate traits, which is consistent with most national cattle evaluations. Thus, these factors directly relate to EPDs from national cattle evaluations.

It is important to note that the table factors (Table 1) do not represent a direct comparison among the different breeds because of base differences between the breeds. They should only be used to compare the EPDs (AB-EPDs) of animals in different breeds. To reduce confusion, breed-of-sire means (i.e., one half of full breed effect; breed-of-sire means predict differences when bulls from two different breeds are mated to cows of a third, unrelated breed) for animals born in 2024 under conditions similar to USMARC are presented in Table 2.

The adjustment factors in Table 1 were updated using EPDs from the most recent national cattle evaluations conducted by each of the 18 breed associations (current as of January 2026). The breed differences used to calculate the factors are based on comparisons of progeny of sires from each of these breeds in the Germplasm Evaluation Program at USMARC in Clay Center, Neb. These analyses were conducted by USMARC geneticists Larry Kuehn, Bailey Engle and Warren Snelling.