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BeefTalk: EPD Accuracy – Contemporary Groups

Good Contemporary Group Data Good Contemporary Group Data
A lot of data is discarded because it does not meet organizational criteria.

By Kris Ringwall, Beef Specialist

NDSU Extension Service

The easy part is data collection. The tough part is having enough cattle treated alike so the calculated number based on the data set actually means something.

A lot of data is discarded because it does not meet organizational criteria. For example, when calves are split within different management options, the performance in those different options is more than likely not the same.

Calves on different pastures do not have the same opportunity to gain weight. The utilization of the data for genetic evaluations is compromised if those management groups are not noted in the data sheets sent to the recording organization.

Good data comes from contemporary groups, which are essential to obtain usable data. Contemporary groups are same-sex calves maintained under similar management in the same location and environment. It’s a simple concept, but not a simple process when managing a herd of cattle.

For example, as cattle are moved around and re-sorted for breeding, the contemporary groups can be reduced in size. It is best to try to maintain a decent number of calves within contemporary groups.

If one reads the guidelines for data organization, those recommendations should be readily available. For example, if one goes to, one can find the guidelines for submitting records to the Angus association.

The association notes that “a useful contemporary group size is 10 or more animals of the same sex born within a 90-day period and weighed within a three-day window.” This parameter is important to understand so the data submitted can be utilized to calculate the expected progeny differences (EPDs) within the National Cattle Evaluation.

The desired outcome requires good planning and understanding of the definitions. In this case, producers must plan the process they are going to implement within the herd to maximize the number of acceptable records eligible for submission to the database.

Planning needs to start now and be followed through the entire time the calf needs to be part of the allotted contemporary group. Many times after calving, calves from a contemporary group are split up and put in smaller groups to be evaluated for various traits. This reduces the number of calves within the contemporary group and distracts from the data.

For example, the sending of a particular sire’s calves to different feed yards to see how they perform in the different environments, especially when the number of calves from that sire are limited. That would be a way to evaluate feed yards, but at the expense of losing genetic data. The more calves in a contemporary group, the better the estimate of the average of the desired trait and the better the distribution of estimated weights. Plan first and then make sure contemporary groups are properly maintained so the estimate of the individual’s performance, in respect to the average of the contemporary groups, may contribute to the National Animal Evaluation for a breed.

The utilization of sire data needs to start at the front end of the process with the submission of good data. The methods utilized by the many breed associations today are very effective at providing education and estimates of genetic potential, which in this case is EPDs.

However, as breeders of cattle, it ultimately is up to individual breeders to submit data that will allow for the maximum number of cattle within the breeder’s operation to be added to the national database. Why go through all the effort of selecting good cattle and building good breeding programs only to have a higher percentage of the data fall out of the database due to mistakes made in data collection or the assigning of contemporary groups?

Astute breeders understand data. Set some aside time to reread your association’s guidelines for data collection.

Understanding the rules is worth it.

May you find all your ear tags.

Your comments are always welcome at

For more information, contact the NDBCIA Office, 1041 State Ave., Dickinson, ND 58601, or go to on the Internet.

NDSU Agriculture Communication

Source:Kris Ringwall, (701) 483-2348, ext. 103,
Editor:Rich Mattern, (701) 231-6136,
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