Sheep pregnancy scanning benchmarks

Page last updated: Tuesday, 6 December 2022 - 4:18pm

Please note: This content may be out of date and is currently under review.

Sheep pregnancy scanning occurs at around 90 days after joining and is performed by a skilled operator using an ultrasound scanner. Pregnancy scanning is an important tool to understand the potential of the lambing season and to efficiently manage the ewe flock.

The Pregnancy Scanning Benchmarks Tool shows the range of reproductive rates in the WA sheep flock and will help you to understand where your flock's scanning results fit.

Pregnancy scanning is conducted around 90 days from joining and is done with an ultrasound scanner. Producers can choose to scan for:

  • pregnant or not, sometimes called wet and dry scanning, which predicts pregnancy status (ewes pregnant per ewes joined)
  • multiple foetuses to determine litter size – reported as reproductive rate (number of foetuses per ewe joined) percentage.

Scanning for litter size is considered best practice as it allows producers to know the potential lambing and the relative feed requirements for the pregnant ewe for accurate feed budgeting. It also allows the producer to understand the potential lambing in that season.

For more information on pregnancy scanning and reproductive rate please see the links section.

The Pregnancy Scanning Benchmarks Tool will help understand where your flock’s scanning results fit with other producers across the agricultural zone of Western Australia. The data shown has been gathered from pregnancy scanning contractors in WA. Currently the benchmark tool includes data from approximately 1.3 million ewe scans from 2016 to 2022.

Reproductive rate is calculated using the pregnancy scanning for litter size data and is the total number of foetuses divided by the number of ewes joined. It is an expression of both fertility and prolifacy.

Conception rate is usually expressed as the number of ewes pregnant divided by the number of ewes joined and gives a measure of fertility.

The reproductive rate is influenced by the breed of ewe, her nutritional status at joining, the success of joining (ram performance), the time of joining and whether it is in the normal breeding season.

Reproductive rate can be used to determine likely supplementary feeding and stocking rates for lambing, determining lamb survival rate and mapping the progress of genetic selection for reproduction traits.

To view the latest pregnancy scanning rates (reproductive rate) of WA sheep flocks, please view the Pregnancy Scanning Benchmarks Tool.


Rebecca Butcher
Katherine Davies