Selecting the right genetics

When selecting sheep, producers should be guided by the breeding program goals or breeding objectives identified in the enterprise business plan.

In selecting for a breeding objective, it is important to remember that a ram can potentially influence the genetic makeup of 40-60 lambs per year and is the main driver of ongoing genetic improvement. A ewe can generally only influence one or two lambs per year, so an investment in ram genetics is likely to deliver greater genetic gain.

The performance of an individual sheep, and its appearance, is governed by two genetics and the environment.

In selecting sheep to meet a particular breeding objective, producers need to determine how much of what they see in an animal is an expression of the genetics and how much is due to environmental factors such as animal husbandry, nutrition and seasonal conditions. Breeding values are the best way to do this.

Breeding values

Breeding values allow producers to evaluate an animal's genetic potential for a range of traits that directly impact on profitability.

Breeding values enable producers to:

• Reduce the risk associated with ram selection.
• Improve the rate of genetic gain.
• More reliably meet market specifications and improve overall productivity.

There are two breeding values for sheep:

1. Australian Sheep Breeding Values (ASBVs) - enable genetic comparisons across flocks within a breed and across breeds among terminal sire breeds.
2. Flock Breeding Values (FBVs) - enable genetic comparisons of sheep only within a flock.

Having identified the traits that are important to the enterprise, producers should look for breeding stock with desirable ASBVs for their selected traits.

LAMBPLAN and MERINOSELECT help producers understand and use ASBVs in their sheep production enterprise.

Breeding values and visual assessment

How an animal's genetic potential interacts with environmental factors ultimately determines how the genetic potential is expressed and, therefore, the productive potential of the sheep.

The visual assessment of sheep also enables the assessment of traits for which ASBVs have not yet been established.

When selecting breeding stock, it is recommended that more animals than needed are initially selected based on ASBVs. Producers should then make final decisions based on visual appraisal.

A selection of visually assessed traits can now be scored and reported as breeding values by Sheep Genetics in the same way as measured traits using the Visual Sheep Scores booklet.

More information

• Module 9: Gain from genetics from the Making More From Sheep producer's manual
• Sheep Genetics
• EDGEnetwork