AMERICAN ANGUS ASSOCIATION - THE BUSINESS BREED

In the American Angus Association’s weekly genetic evaluation, the genomic results are incorporated using a single-step method to calculate EPDs. Including genomic results helps to better define the genetic relationship among animals. With the traditional pedigree-based approach of EPD predictions without genomics, relationships between animals are determined by pedigree alone. For example, pedigrees would dictate all full-siblings have a genetic relationship to one another of 0.5, and the relationship between grandparent and grand-progeny would be 0.25. Because of the way DNA is inherited, differences in these relationships are present. The animal’s genotype allows us to determine which flush-mates or siblings are more genetically related. In fact, genomic testing allows all pedigree relationships to be better defined.

These relationships are quantified using SNP data (genomic results) known as an animal’s genomic relationship. For example, if a newly tested animal shows to have a strong genomic relationship. For example, if a newly tested animal shows to have a strong genomic relationship to an animal who is proven to excel for a trait like marbling, then the newly-tested animal’s marbling EPD will increase. On the contrary, if an animal is found to be more related to a low performing animal in the pedigree, its EPDs will adjust accordingly.  

Animals more closely related to ancestors with large amounts of actual performance data (weaning weights, yearling weight, carcass data, etc.) and genomic results will experience a greater benefit from genomic testing, including greater EPD accuracy and spread, than those with less data in the Association database.

Importance of phenotypic performance data 

Genomic testing is not a replacement to performance data recording. Breeders sometimes ask if it is no longer necessary to collect weights and measures, such as weaning weights, scan/carcass data, and heifer breeding records. On the contrary, phenotypic measures continue to be an important part in further developing improved genomic panels and refining this technology over time.

Table 1. Progeny equivalents (PE)

**Carcass trait PE equates to actual carcass harvest data, not ultrasound scan equivalents.

Trait

2024 PE

Calving Ease Direct

24

Calving Ease Maternal

18

Birth Weight

22

Weaning Weight

25 

Yearling Weight

20

Yearling Height

14

Dry Matter Intake

15

Scrotal Circumference

11

Docility

10

Foot Claw Set

12

Foot Angle

12

Pulmonary Arterial Pressure

7

Hair Shed Score

9

Heifer Pregnancy

16

Maternal Milk

38

Mature Weight

14

Mature Height

9

Carcass Weight**

13

Marbling Score**

10

Ribeye Area**

10

Backfat Thickness**

20

Percent ranks provided with genomic results

Percent ranks (1-100) are provided by the American Angus Association to assist in establishing direction of interest for each trait, as illustrated in Table 2.  

If you are making selection decisions for traits that have an EPD provided by the Association, then the EPDs should be considered the selection tool of choice. The EPD and accuracy account for all sources of information available on the animal of interest (e.g., pedigree, own record, weights/measures, genomic results). Using EPD and genomic percent ranks separately leads to double counting information and will decrease selection efficiency. With that, the EPD provides the most accurate and up-to-date information as it is updated every week; whereas, genomic percent ranks only update once a year and are a by-product of the system. 

EPDs with genomic data are the best estimate of an animal’s  genetic value as a parent combining all available sources of  information. Genomics permit higher prediction accuracies for younger animals and characterize genetics for traits where it’s difficult to measure the phenotype. To learn more about available genomic tests and place an order, click here.

Table 2. Establishing direction of percent ranks.

Trait

PE

Observation

Calving Ease Direct

1%

 More Unassisted

Calving Ease Maternal

1%

 More Unassisted

Birth Weight

1%

Lighter

Weaning Weight

1%

Heavier

Yearling Weight

1%

Heavier

Milk

1%

More Maternal Milk

Yearling Height

1%

More Hip Height

Mature Weight

1%

Larger Cow Weight

Mature Height

1%

More Cow Height

Dry Matter Intake

1%

Eat Less

Docility

1%

More Docile

Foot Claw Set

1%

Less Toe curl, More Symmetrical Toes

Foot Angle

1%

Less Extreme Angle and Toe Length/ More Ideal Angle (45°) and Toe Length

Pulmonary Arterial Pressure

1%

Lower PAP Score

Hair Shed

1%

Earlier Summer Shedding

Heifer Pregnancy

1%

Increased Pregnancy Probability

Scrotal Circumference

1%

 Larger Size

Carcass Marbling

1%

Greater

Carcass Ribeye

1%

Larger

Carcass Fat

1%

Leaner

Carcass Weight

1%

Heavier

Tenderness

1%

More Tender

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