Contemporary Groups… You can’t have accurate EPDs without them
Now that ASA is an official team member of the International Genetic Solutions group, with an even larger performance database, today is probably a good time for a refresher on contemporary group designations. Perhaps the most important component of data submission and therefore EPD accuracy, is accurate contemporary grouping. After many years’ worth of tracing down breeder questions relative to EPD changes, most times we find that inaccurate contemporary groupings are the cause of the issue.
Let’s review what a contemporary group is relative to genetic evaluation. A contemporary group consists of animals that have been exposed to the same external environment. ASA currently defines this in five, automatic contemporary group splits:
1 – Same sex
2 – Born in the same herd and season (within 90 days)
3 – Managed together and treated alike
4 – Have the same weigh date
5 – All Calves born from first-calf dams
Items 1, 2, 4 and 5 are self-explanatory.
Managed Together and Treated Alike
Most contemporary group errors are made when submitting weaning data in the management code and management group sections of ASA forms. Management code details are noted first. Please remember to note any designations when submitting performance data.
ASA Management Codes
1 – no creep, raised by natural dam
2 – received creep feed, raised by natural dam
3 – fed for show, within show/sale group
4 – embryo transfer
5 – irregular, such as twin, sick, injured
ASA Management Group
The second section contains optional management group information. Most generally this is where the confusion comes in. If one group of cows are run on irrigated pasture with exceptional forage resources and another group of cows are grazing native prairie grass there will probably be a difference in the weaning weights of the calves. Therefore, the calves in each group should be reported as being in different management groups even if they have the same weigh date. For example, the group code could be 1 for irrigated pasture and 2 for native prairie grass.
Commonly, breeders think calves can be grouped together even if they were raised in different pastures. Most think that differences in “prairie grass” pastures on the same ranch are minimal. Studies have shown that pastures next to each other that visibly look the same can still cause large discrepancies in weaning weights among the calves in those different pastures. Inaccurate submission of the data from these two pastures as the same group causes negative and inaccurate effects on the EPD of both the calf and the entire pedigree. For example, the group code in this case could be 1 for one of the pastures and 2 for the other pasture, even if the weigh dates are the same.
To most producers, larger contemporary groups are perceived to equate to more accurate EPDs. This is true in reference to higher calculated accuracy values such as are listed by each trait in the Sire Summary. If larger groups should be split into smaller groups due to pasture differences, the EPDs you generate by doing this will be more informative and more accurately relate to the true differences.
Contemporary Group Example
A breeder has weaning weights on 15 bull calves each from three different sires. Each sire had 5 calves in three different pastures. If we ignore the rules and group all 45 calves together, it is true that the calves’ EPDs will have a slightly higher calculated accuracy than if we went by the book and sorted them into 3 contemporary groups. On the other hand, grouping all the calves together will actually lower their factual accuracy compared to placing the calves in 3 groups.
As a breeder we do see value in knowing that a sire can perform across multiple different environments and therefore understand that the accuracy value is going to increase due to the performance in the three pasture groups as opposed to a single-contemporary group situation. This example helps us remember that we are trying to identify the genetic merit in an animal as opposed to the difference our environment causes. Once you think about it is simple. Just doing the simple things right will enhance the accuracy of your EPDs and the EPDs of other breeders using the same genetics. Just take a few minutes and double check your data before sending it in.
Common Pitfalls when turning in performance information
- Don’t bias ratios, take weights on the entire crop – not just the top 50%
- Accurately record Management Codes
- Split off Twins
- Split off Sick or Injured calves
- Make sure to denote those animals pulled out and fed, such as show cattle
- Accurately record Pasture Management Groups
- If you cut bulls at weaning record sex as a bull not a steer
- Make sure most calves are between 160 and 250 days of age for weaning
- Contact the ASA before weighing if you have questions
- Correct errors if data was recorded incorrectly
