Contemporary Grouping
Everything you need to know to ensure your calves get the credit they deserve.
DEFINING GROUPS
Contemporary groups are the cornerstone of genetic evaluation. They are the best way to account for environmental effects so that remaining differences among animals may be attributed to genetics, ultimately resulting in expected progeny differences (EPDs).
A contemporary group is a set of animals that have had an equal opportunity to perform such as same sex, managed alike, and exposed to the same environmental conditions and feed resources.
Breeder Defined
The responsibility of proper contemporary grouping lies with the individual breeder. Consideration should always be given to the way the calves are managed and to their nutrition. In many cases, one contemporary group per sex is sufficient. However, differences can exist within the same operation that requires the establishment of two or more contemporary groups. Management and group codes may be helpful in these cases.
Success Starts at Birth
Contemporary groups are defined at birth. The number of contemporaries either stays the same or becomes fewer as animals age and are separated from each other for management reasons. Contemporary groups cannot be recombined after herd mates are separated from their defined birth groups.
A typical plan is to take weaning and yearling weights and measurements on all calves on the same day and to include as many calves in the contemporary group as possible. Then, the management and group codes can be used to specify known group differences.
Examples of group code use:
- Calves from 2-year-old dams in one pasture may be reported as Group A, while calves from mature cows in another pasture are Group B.
- The entire calf crop is reported as Group A, but an orphaned calf is placed in Group B, and a chronic sick calf is placed in Group C.
Each of the categories above will be a separate contemporary group for comparative purposes as indicated by a different lot identification (Lot ID) in the upper left-hand corner of the Angus Herd Improvement Records "Sire Summary" sheets.
GROUPING GUIDELINES
What makes a group?
A set of calves (two or more) that are the same sex, managed alike and exposed to the same environment.
Calves of differing sex (bull or heifer) are automatically placed in separate birth contemporary groups.
How will groups be split?
- 90-day birth date window
- Management codes (creep vs. non-creep)
- Group codes
- Weaning dates more than three days apart
- Location codes
- Registered vs. commercial dams
- Natural vs. embryo transfer (ET) calves, registered Angus vs. other recipients
- Submitting data on calves that could be in the same contemporary group on different days or through different forms (AAA Login, spreadsheets, or paper forms).
NOTE: Sending data on calves at later dates than their other contemporaries can cause unwanted groups to be formed. These calves will not be joined with the previously submitted calves.
Manage Your Herd
Register and transfer animals, track and submit herd data and pay your bill.
BUILDING CONTEMPORARY GROUPS
Birth types separate calves
Natural calves: Contemporary groups for natural calves are separated by whether the dam is a registered Angus or commercial female.
Embryo Transfer (ET) calves: They are not grouped with natural-born calves. ET calves from registered Angus recipient females are assigned to a separate group from ET calves out of other non-registered recipient females.
Calves born within a 90-day period of one another can be placed in the same birth contemporary group.
The birth group code is used to distinguish groups of calves whose mothers were not managed in the same environment before the birth of the calf (e.g. different nutrition resources during gestation).
Group codes are defined by the breeder, consisting of one letter or number. (e.g. A-B-C or 1-2-3).
It is important for producers to place individual calves in the correct birth contemporary groups as this group will follow the animals for the entirety of their life. The birth contemporary group criteria will be the first building block to form weaning contemporary groups.
Weaning date separates calves
Calves weighed outside of a three-day window will be split into separate groups. For example, calves weighed on Monday, Tuesday and Wednesday can be included in the same group.
Divide by codes
The management code designates whether or not calves were creep-fed or supplied supplemental feeding and separates them accordingly.
Code 1 is for non-creep-fed calves, while code 3 is for creep-fed calves.
The group code is used to designate a set of calves managed differently from another set of calves. Calves from different groups or pasture units can be designated by using a letter code, such as A, B, C or D. Orphaned or extremely sick calves should be assigned a separate group and not be compared against their normal herd mates.
Group codes are defined by the breeder, consisting of one letter or number. (e.g. A-B-C or 1-2-3). Weaning groups are the building blocks of yearling groups.
Yearling weight date separates calves
Yearling weaned outside of a three-day window will not have the same yearling contemporary group. For example, calves weighed on Monday, Tuesday and Wednesday can be included in the same group.
Divide by codes
Additional group codes may be assigned to distinguish different management cases, if necessary.
Group codes are defined by the breeder, consisting of one letter or number. (e.g. A-B-C or 1-2-3).
TRACK HERD PROGRESS
Use the Association’s AIMS tool to create customized herd reports and format data for submission.
GROUPS, RATIOS AND EPDS
Contemporary grouping allows animals to be evaluated on how well they performed compared with their herd mates raised under similar environmental conditions. This grouping accounts for environmental or unequal treatment effects between two groups, so that heritable differences, such as EPDs, can be predicted.
For most traits, two or more animals of the same sex are necessary in the contemporary group for the EPD to be calculated, assuming other data edits are met. Some traits (feed intake, hair shed, etc.) will require five animals in a contemporary group. Each animal is compared relative to the average performance of the contemporaries in the defined group. You cannot have EPDs beyond a pedigree index interim EPD without contemporary groups. A contemporary group of one animal does not provide any information to compute EPDs from the Association's National Cattle Evaluation.
There are 10 bull calves weaned at your farm or ranch (treated alike, same sex, fed/managed the same). The bulls form one weaning contemporary group. You send two calves to the bull test station and keep the remaining eight at home. Their yearling and ultrasound records will be processed as two separate contemporary groups, not as one.
If you send one bull to a test station, this creates a contemporary group of one for the yearling and ultrasound data. Association ratios for these traits will be 100, and the animal's own yearling and ultrasound performance will not be used in evaluation procedures for EPDs.
A ratio is the performance of an individual animal relative to the average performance for his or her contemporaries. Contemporary groups should include as many animals as can be accurately compared.
Continuing our example, the 10 bull calves at weaning weighed an average of 600 pounds (lb.). One calf weighed 630 lb., so he is 5% above the average of his contemporaries.
His ratio is 105. Ratio = (630 ÷ 600) x 100 = 105
Another calf weighed 570 lb., which is 5% below the contemporary group average of 600 lb.
His ratio is 95. Ratio = (570 ÷ 600) x 100 = 95
In the calculation of EPDs, the animal's own record (a weight or measure) is used relative to the contemporary group's average performance. It is sometimes a misunderstanding that the numerical ratio (like the ratio computed above) is used in the computations. Ratios can be a within-group tool; however, the use of more advanced selection tools, like EPDs, provides comparisons among all animals in the breed with greater accuracy.
Interested in learning more?
Watch the video below or click here to discover how to understand and create contemporary groups.
