What is a Contemporary Group?
Contemporary groups within performance recording are a group of individual animals who have had equal opportunity to perform. They have been run under the same conditions and are comparable amongst one another within the analysis for any trait observed and recorded by the breeder.
How does a Contemporary Group form?
A contemporary group is automatically formed (generally) based on the following:
- Herd of measurement
- Birth year
- Embryo transfer (ET) vs natural and AI
- Twin-born vs single-born
- Sex
Then there are factors that are influenced by the breeder that further contribute to group formation:
- Observation date (the date the animals were weighed or measured)
- Age slicing or Calf age spread (age of oldest animal vs the age of youngest, generally being 45 day split for early in life traits and 60 day slit for later in life e.g. carcase data)
- Sex (bulls vs steers)
Contemporary groups can be further influenced by information provided by the breeder through:
- Management Groups (breeder defined)
What is a Management Group, how do I define it, and do I really need one?
A management group provided by the breeder further separates a group of animals who have performed under different non-genetic factors. A management group is a three-character reference you provide on your performance submission to indicate if an individual or group of animals have been treated differently to the others. These are factors beyond those listed above.
For example, you might choose to define a management group based on:
- Injury/Illness.
- Grain fed vs pasture fed.
- A mob split over different properties with different environments (pasture quality, seasonal factors).
An example of defining a management group on your performance data submission would be an animal who was removed from the main mob to be treated for injury. This could be identified on your performance submission form using a management group code: INJ.
Why should I manage my animals to maximize contemporary group size.
Maximizing contemporary group size increases the reliability, accuracy, and fairness of genetic evaluations by providing stronger comparisons among animals raised under the same environmental conditions. This results in more accurate WBVs and better breeding decisions.
Benefits of Larger Contemporary Groups
Separates genetics from environment
- Animals raised under the same conditions experience similar environmental effects.
- Larger groups make it easier to determine whether performance differences are due to genetics rather than management or environmental variation.
Increases accuracy of Wagyu Breeding Values (WBVs)
- More animals within a group provide more data points.
- This allows genetic evaluation systems to estimate an animal’s genetic merit with greater confidence.
Improves ranking of animals
- Larger groups help distinguish superior and inferior genetics more reliably.
- Breeders can make better selection decisions.
Reduces bias
- Small groups can be heavily influenced by unusual environmental factors or individual animal effects.
- Larger groups reduce the impact of these random influences.
Enhances connectedness between herds
- When large contemporary groups are linked through common sires or genetics, comparisons across herds and years become more accurate.
How large is an effective Contemporary Group
As contemporary group size increases, the accuracy of Wagyu Breeding Values (WBVs) also improves because more animals are available for comparison. However, the benefit does not increase indefinitely.
The greatest gains occur when moving from very small groups to moderate-sized groups:
- 2–5 animals: minimal accuracy
- 10–20 animals: substantial improvement
- 20–40 animals: higher accuracy
- Above 40 animals: further improvement occurs, but at a much slower rate
In other words, the returns begin to diminish once groups reach around 20–40 animals.
Management Still Comes First
While larger groups are generally better, accurate grouping is more important than group size alone. Breeders should never combine animals that have been managed differently simply to create a larger group. Two correctly defined groups of 20 animals will provide more reliable information than one poorly defined group of 40 animals.
Key Take-Home Message
The biggest gains in genetic evaluation accuracy come from increasing contemporary group size from small numbers to around 20–30 animals. Beyond that point, improvements continue but at a diminishing rate. For most breeders, the goal should be to maintain the largest possible contemporary groups while ensuring all animals have had an equal opportunity to perform
