Lamb Production

Developing Adult Equivalents for extensive-zone sheep

Sheep Central, February 10, 2015

A recent project developing an adult equivalent methodology for cattle commissioned by Meat & Livestock Australia has raised the question of how the grazing load of sheep is calculated, and how it compared to cattle in extensive rangeland areas.

The Dry Sheep Equivalent (DSE) is an established system for sheep, however suggested conversion ratios for DSE:AE range anywhere from 6:1 to 12:1.

The conversion chosen has a big impact on calculations on relative numbers that can be carried, and on the relative performance of sheep and cattle enterprises, when they are analysed on a common basis (either AE or DSE).

To address this, consultancy Bush AgriBusiness, which was contracted by MLA to develop the cattle AE model, has also applied the AE methodology to sheep, to allow an ‘apples & apples’ comparison to be made between sheep and cattle grazing under extensive rangeland conditions.

This was done by determining a sheep’s energy requirements using the ‘Nutrient Requirements of Domesticated Ruminants’ report (also known as Australian Feeding Standards, published by CSIRO 2007).

Unlike cattle where different breed types affect energy requirements, only a single set of AE tables was necessary for sheep. The differences between breeds in terms of performance is captured by the AE ratings, being based on performance.

The process determined a DSE:AE conversion of 8.4:1, although the AE calculations are for sheep grazing under extensive rangeland conditions, consistent with cattle AE calculations, and may not be applicable for all circumstances (for example, highly productive southern systems).

Click here to access the set of sheep AE tables.

Click here to view the beef AE article and tables.

 

  • Ruminant nutrition advice for the application of the AE methodology to sheep was provided by Toowoomba nutritionist and vet, Dr Shane Blakeley, while David Counsell of Dunblane, Barcaldine, contributed quality sheep performance data and knowledge to the project.

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