Management groups
Meat & Livestock Australia September 22, 2021
An animal’s performance is a result of environmental and genetic factors. To capture the genetic potential of an animal (and calculate ASBVs), we need to account for the environmental and management influences. The environmental differences between animals which may influence their performance are captured by management groups, which should reflect how animals are run on farm prior to recording trait measurements.
Management groups are submitted by the breeder and should capture differences in management or environment that result in differences in performance. Examples of different management conditions may include:
- difference in feed or nutrition availability
- supplementary feeding a certain mob
- a stress event occurred in one mob e.g., the trough broke in one paddock meaning that mob was without water for a couple of days
- a ‘hospital mob’ of animals that were sick e.g., a mob of lambs with dams that had mastitis
Mobs run in different paddocks do not necessarily need to be submitted in different management groups. Where conditions are similar across two paddocks, animals can be submitted in one management group. The performance of animals in different management groups is not directly compared to each other. Therefore, large management groups allow for more animals to be compared to each other, creating a more robust evaluation of genetic merit.
Every measurement is submitted with a management group, to inform the analysis of which animals were running together under the same management conditions in the lead up to being measured.
You only need to keep track of how animals are managed (management grouped) up to the trait which you are recording. This management group should be entered into your software with the relevant age stage (that matches the age of the animal when it is recorded).
Prior management groups for previous age stage trait measurements are recorded and stored in your software and the Sheep Genetics database. You do not need to keep track of this yourself.
When animals are split out into separate management groups, they will remain split out in the evaluation for the remainder of their life. However, this does not mean you cannot run them together on farm in the same management group in the future.
Things to remember when splitting mobs into management groups:
- It is crucial to have progeny from a common sire represented across management groups and across year drops to provide a ‘link’.
- It is important to ensure that there are progeny from multiple sires (must be more than one sire) in each management group.
- Make sure the sire has multiple progeny of the same sex in the management group (i.e. if it’s a group of ewe lambs, have multiple ewe progeny included from the sires).
- Measure the entire management group for the trait on the same day.
Maintaining effective progeny numbers in each management group is important to ensure accuracy of ASBVs. Effective progeny refers to how useful or valuable the progeny data is in contributing to a sire’s ASBVs. The effectiveness of recording is affected by the amount of pedigree recorded, the number of animals in the group, and the number of sires represented in the group. Effective progeny numbers allow reliable comparison between the sires represented in the group to determine genetic merit. At least eight animals are required per sire, each of the same sex, management group and date of trait measurement. When an animal is grouped out, it remains grouped out for life. This means that animals in different birth groups will never be directly compared as contemporaries at any stage of life for any measurements.