Minimum Contemporary group increase from October
From October 2021, NZAEL is increasing the minimum size of a contemporary group from 2 to 5 animals.
This increase gives four points of reference the animal can be compared with instead of one and will increase the reliability of breeding value accuracy for the industry.
Data from animals with less than 5 individuals in their contemporary group will be excluded from animal evaluation.
More detailed information can be found in the September 2021 NZAEL newsletter
Animals in a contemporary group are reared and managed alike, in the same environmental conditions and with the same feed resources. When grouped in this way, it allows us to compare them on an even playing field.
We can then separate genetic differences from environmental effects and differences in performance are likely due to genetic differences.
Contemporary group testing
Cows are assigned to the same contemporary group if they are herd tested:
- in the same herd (e.g. same farm location and herd number)
- on the same test day (e.g. using am and pm, am only, pm only, OAD)
- belonging to the same age group (2-year-old, 3-year-old, 4-year-old, or 5 to 7 year-old)
- with the same season of calving (spring or autumn under the same sampling regime)
For liveweight, body condition score or Traits Other than Production (TOP), a contemporary group is a group of animals who are:
- in the same herd or mob (e.g. same farm location and herd number)
- weighed/assessed on the same day
- belong to the same age group (2-year-old, 3-year-old, 4-year-old, or 5 to 7-year-old)
- with the same season of calving (spring or autumn)
Note: For TOP and BCS, only 2-year-old records are used.