Performance

At North-South Borders we use Lambplan to performance record all animals in our flock and as a result each animal has an Australian Sheep Breeding Value (ASBV).

ASBVS and Indexes explained.

What are ASBVs?

ASBVs are the units of measurement LAMBPLAN use to analyse animals.

Australian Sheep Breeding Values are an estimate of an animal’s true breeding value based on pedigree and performance recorded information.

They are essentially a projection of how that animals progeny will perform for a range of traits.

ASBV types

• Birth Weight. ASBV is based on measured birth weight adjusted for age of dam. Where birth weights are not available it is estimated as a correlated trait from weights measurements as the lamb matures. The lower the ASBV the lighter is the estimated progeny birth weight potential.
• Weight. ASBVs describe the animal’s genetic merit for growth rate. A positive ASBV means the animal is genetically faster growing.
• Fat Depth. ASBVs describe the value of animal’s genes for fat depth at a constant weight – a negative ASBV means a genetically leaner animal.
• Eye Muscle Depth. ASBVs describe the value of animal’s genes for muscle depth at a constant weight – a positive ASBV means a genetically thicker-muscled animal, and one that will have slightly more of its lean tissue in the higher priced cuts.
• Wool Weight. ASBVs describe the value of animal’s genes for wool weight – a positive ASBV means genetically heavier-cutting animal.
• Fibre Diameter. ASBVs describe the value of an animal’s genes for finer or coarser wool.
• Reproductive ASBVs describe the value of an animal’s genes for lambing and/or marking rate.

What are Indexes?

Selecting animals involves balancing several key traits.

To make selection easier traits can be combined into a selection index.

A selection index combines ASBVs for several traits to give a single value.

This reflects the performance of the sheep relative to the breeding objective of the particular index.

Index types include:

$ Value Indexes: A dollar index indicates the value of an animal based on its suitability for a particular market. The value is given in real dollar figures and expressed a $/ewe joined/yr. For example a dollar index of 105 indicates that a ram will produce $5 extra value for every ewe joined compared to a ram with an $ index of 100.

Desired Gains Indexes: Work on a proportional gain of a combination of traits. For example the Carcase Plus index puts 60% emphasis on increasing growth, 20% on decreasing fat and 20% on increased eye muscle depth.