Ovine Observer

Pregnancy Scanning Benchmarks Tool  

Rebecca Butcher, DPIRD, Moora, WA
Author correspondence:

A new Pregnancy Scanning Benchmarks Tool has been developed to assist sheep producers’ decision-making about pregnancy scanning their flocks, to benchmark scanning rates and improve flock management and profitability. The tool, available on the Department of Primary Industries and Regional Development’s website, is based on an extensive database of nearly half a million results from experienced scanners in WA.

The Pregnancy Scanning Benchmarks Tool shows the range of reproductive rates in the WA sheep flock and allows producers to determine how their ewes perform against others in their region to aid management strategies and optimise their flock’s reproductive rate.
The easy to use tool, allows the user to select for results within years 2016 – 2019, medium rainfall or cereal sheep zone and sheep type – meat or merino. The tool represents reproductive rate as the number of foetuses scanned per 100 ewes joined and displays the data in a bar graph, noting the total number of flocks and ewes used in the comparison.
Figure 1 shows the reproductive rate for Merino ewe flocks in the Central Sheep Zone for early lambing (April and May) while Figure 2 shows the results for mid-winter lambing (June and July).
Figure 1 Reproductive rate of 36 Merino ewe flocks in the Cereal Sheep Zone lambing in April and May
Figure 1 Reproductive rate of 36 Merino ewe flocks in the Cereal Sheep Zone lambing in April and May
The figures demonstrate that the average flock size is slightly higher for early lambing with 2018 ewes compared to 1909 for mid-winter lambing. The shaded bar on each figure represents a flock with a reproductive rate of 135%, which is higher than average for early lambing and average for mid-winter lambing.  Reproductive rates are more variable for early lambing and range from 90 to 180%, although the percentage of farms with a reproductive rate less than 105% or greater than 150% is low.
Figure 2 Reproductive rate of 38 Merino ewe flocks in the Cereal Sheep Zone lambing in June and July.
Figure 2 Reproductive rate of 38 Merino ewe flocks in the Cereal Sheep Zone lambing in June and July


Currently the tool does not include reproductive rate results for ewe lamb mating, embryo transfer or artificial insemination, however these may be included when sufficient data becomes available.

Reproduction support links

The webpage also features links to supporting articles on reproduction potential and marking rates, the value of pregnancy scanning for twins and managing pregnancy in ewes. By understanding the performance of their sheep reproductive rate, producers may be able to determine where their management strategies are working or where improvements can be made. Reproductive rate can also 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.

Pregnancy scanning in Western Australia

The 2018 WA Sheep producer survey showed that the average reproduction rate of the State flock ranges from 1.15 to 1.35 foetuses per ewe, depending on the season. Currently 17% of producers, about 30% of the State flock, scan for litter size, while a further 25% of the flock is scanned to determine whether their ewes are pregnant or not. 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 for that season. As scanning rates increase the data available to the tool increases providing producer with more information about how their ewes perform against other ewes in the region.
By identifying ewes with twins and triplets, producers can manage them differentially to improve lamb survival and production by focusing on twinning ewe nutrition, segregating them into a mob of multiples and providing suitable shelter. With this additional attention, the investment could translate into improved marking rates and more profit from each ewe – particularly with current favourable sheep prices with each additional lamb on the ground worth $85 to $110 each.

Accessing the tool

To access the Pregnancy Scanning Benchmarks Tool search the department’s website for ‘Pregnancy Scanning Benchmarks’ at
The tool will continue to evolve as more information becomes available. Pregnancy scanning services which do not currently contribute their data are encouraged to participate to improve the understanding of reproduction rates in WA.