This section covers:
- Pedigree recording
- Linkage
- Grouping
- Avoiding selective recording
Pedigree recording
You must have full pedigree on your flock to use MateSel properly. There are two reasons to have full pedigree, the first is to get more accurate ASBVs. The second is to keep track of inbreeding.
Plus having full pedigree means you will have more accurate ASBVs and make more genetic gain.
When you have dam pedigree, the ASBVs will take account of:
- Full siblings
- Dam age
- Dam’s maternal genetics
- Birth type and rear type
- Removes mating bias (mating good rams to poor ewes or vice versa)
If you are interested in reproductive traits, you must record dam pedigree.
When you have sire pedigree, the ASBVs will take account of:
- Linkage
- Better accuracy
- Improves the sire’s ASBV’s
Syndicate mating is a sub-optimum practice in a seed-stock flock. The benefits of MateSel are lost if you use syndicate matings.
Linkage
Linkage is vital for across flock evaluation. It allows us to compare ASBVs across the country. Without linkage, we don’t know how much of the difference in performance between groups is due to environment and how much is genetic.
You should consider linkage at the following levels:
- Between contemporary groups within a drop
- Between drops within a flock
- Between flocks or sites
- Between strains and breeds
How do you get linkage?
Use of common sires is the main method to ensure linkage:
- Use sires from outside flocks
- Participate in young sire programs
- Enter in Central Test Sire Evaluation / Resource Flocks
- Ensure link sires have adequate progeny numbers
The analysis does not consider linkage between groups within a flock so take care to ensure groups are well linked.
Your linkage checklist:
Do external sires:
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Have progeny in more than one flock?
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Have decent progeny numbers (>10)?
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Have sire of sire showing?
Do sires:
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Have decent numbers of progeny recorded?
Does the flock:
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Have sires used in consecutive years?
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Have common sires between AI and back up matings?
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In full pedigree flocks dams help link across time
Grouping
Why group animals?
- Compare apples with apples
- Separate animals that have been treated differently
- Ensure data is accurate
You group animals by supplying a management group in your software with each measurement.
When you submit data to Sheep Genetics, you do not need to over complicate the grouping. Once the data is received, Sheep Genetics will make what are called contemporary groups. The table below shows what you need to submit and what Sheep Genetics does.
Management groupsUser defined – in software Birth Groups (Group)
Sub-groups
|
Contemporary groupsCreated by analysis
Slicing for age differences
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Avoiding selective recording
It is best to measure all of the lambs that are born. This will produce better quality data that represents the flock’s range in performance.
Not recording the lower performing animals will severely bias you data. It will in fact penalise the higher performing animals. When the lower animals are taken out, the average of the group is higher so the top animals look less distinguished.
Example 1: All lambs in the drop are weighed. The average is 30kg and the heaviest is 37kg. This means it is 7kg heavier than the average.
Example 2: Selective recording has taken place so not all lambs in the drop are weighed. The average is the 34kg and the heaviest is 37kg. This means it is now only 4kg heavier than the average.
