Estimated Breeding Values

What are they?

EBVs are a tool that can provide you with objective information about a ram's genetic potential. EBVs are particularly useful for traits that are not easy to see on sale day (such as eye muscle depth (EMD) or lamb survival (NLW)). EBVs allow breeders to compare the genetic potential of animals independent of the environment and location.

That said, EBVs are not a substitute for a full visual inspection of your potential ram team. Checking rams for conformation and physical soundness prior to purchase is still essential. Cull faults are cull faults, regardless of how good the EBVs are.  

Everyone's sheep breeding enterprise is unique. We all farm in different environments and there are a host of other factors that determine what our ideal production system is: scale, number of staff, parasites and diseases, market demands, and the 'what gets me out of bed?' factor. EBVs are simply a tool that help to you find the genetics that can produce the sheep that best suits your needs.

How can I access EBVs?

Anybody can access EBVs via the MERINOSELECT website. If you are a ram buyer, should should ask your ram breeder to supply you with EBVs on their sale rams. If you are a ram breeder, your should either get in touch with NZM, or go directly to Sheep Genetics who will be able to support.

Since 2013, the number of fine-wool ram breeders in New Zealand generating EBVs has jumped from three to over twenty. NZM has worked with New Zealand's fine-wool ram breeders to help them move their data into genetic evaluation systems and produce EBVs for their stud ewes and rams. The MERINOSELECT system managed by Sheep Genetics Australia is directly suited to fine wool sheep because of its depth of data and genetic parameters and is used across Australia and New Zealand.

The great benefit of this work is that, with access to EBVs, commercial ram buyers are able to better differentiate between rams - based on the rams' genetic potential - across all characteristics that are desirable for their particular production system. Rather than relying solely on a visual assessment of a ram, ram buyers can use a combination of EBVs and visual appraisal to assess the ram. This is particularly useful for identifying rams with superior genetic potential in traits that cannot be seen in the sale pen, i.e. disease resistance. 

Selecting Fine Wool Genetics for Your Farming Business

Grab a percentile table and a ram catalogue, and follow the video to hear from Mark Ferguson, director of neXtgen Agri, on what to keep in mind when choosing your fine wool rams and ewes.

Resources

This is a series of quick links to useful resources:

• Estimated breeding values - a guide for ram buyers

• Breeding objective tool

• A pocket guide to ASBVs (Australian Sheep Breeding Values)

• ASBV percentile band table

• Using the Sheep Genetics selection indexes

• MERINOSELECT

Linkage tips for Estimated Breeding Values

It's important to consider linkage in your recorded stud flock as mating approaches. Genetic Linkage is the sharing of common genes, for example, when a ram has progeny in multiple flocks there is genetic linkage. Genetic linkage is an essential part of producing EBVs as it accounts for the difference in environments between sites, allowing animals to be compared across flocks. If the Sheep Genetics EBV analysis cannot link your EBVs with other flocks, you will receive a within-flock breeding value, and not be comparable to others.

How often does my flock have to link to other flocks?

It's recommended you use genetics from other flocks routinely. Sheep Genetics calculates linkage using the last 5 years of pedigree.

Where do I need linkage?

Linkage is required:

• Between flocks – genetics measured in your flock and in another flock

• Between years – common sires across years

• Across groups – common sires across management groups

Across flock linkage is calculated by the analysis across years and across groups. However, linkage needs to be managed by breeders.

Do I need to be linked for all traits?

To be linked for a trait group, the link sire needs to be linked for the trait. This sire needs to have progeny recorded for the traits you want at both sites he is used, i.e. if you want footrot BV linkage, both of you must be collecting footrot data on your shared ram's progeny.

Ways to ensure across year and group linkage;

• Rule of thumb: use at least 1 sire per 10 sires used that has progeny recorded in a previous year.

• Manage progeny from each sire across management groups

Ways to become linked across flock;

• Use at least 1 sire used in other Sheep Genetics flocks per 10 sires used. Artificial Insemination (AI) is a good way for many breeders to use the same sires

• Buy new sires (or semen) from other flocks that have data in Sheep Genetics

• Sell rams to other Sheep Genetics recorded flocks for use as sires

• Use paternal half-sib sires (i.e., sons of one ram) across years, or groups, within a flock and use paternal half-sib rams in different flocks (commonly done through natural mating)

• Participation in linkage programs such as Young Sire Programs that share young sires across flocks or Sire Evaluation schemes (i.e. a Central Progeny Test)

A rule of thumb, 30 progeny are the minimum required from one link sire and should be managed in all subgroups.

Strong linkage is important and the stronger linkage is the more it reduces the risk that animals compared across flocks will be inaccurately compared.

Using a selection index

A selection index can help you balance the traits that are most important to you. EBVs for several traits are weighted and combined to give a single index value for a particular ram.  

There are different kinds of indexes, and the type of index that suits you will depend on your production system. Sheep Genetics provides a range of indexes, depending on your breeding objective.

Bear in mind that indexes are developed for a general breeding objective and can only tell whether the ram you are considering will help you move in the general direction you want to move.  

It is important to check the ram's specific breeding values for traits that are important to you (both desirable and undesirable traits) to make sure there are no unwanted surprises down the track!

MERINOSELECT

MERINOSELECT generates across-flock and across-breed genetic information (in the form of breeding values) for fine-wool sheep in Australasia. The breeding values are updated twice a month by Sheep Genetics, using data submitted by breeders from across the industry. 

Click here for more information about the MERINOSELECT database and using estimated breeding values to assess the genetic potential of fine-wool sheep.

Sire Genotyping

What is involved?

Each year, fine-wool ram breeders collect DNA samples from their rams and DNA is extracted from each sample and genotyped using SNP chip technology (an analysis that defines the DNA sequence at different locations across the genome).

Why has the information been collected?

These genotypes are being used to build a reference population for the New Zealand fine-wool industry, particularly the footrot breeding value project - FeetFirst.