This blog post was adapted from the OMAFRA Factsheet “Pregnancy Scanning: Management Tips” (AGDEX 433/22) by A. O’Brien.
Introduction
Pregnancy scanning, using real-time ultrasound equipment, is a useful management tool for Ontario sheep and goat producers. When scanning is performed within the recommended time frame by trained professionals, accuracy of identifying animals that are not pregnant and counting the number of fetuses is high. Pregnancy scanning can be used to assign open ewes to new breeding groups, make culling decisions, and optimize feeding management based on expected litter size.
Benefits of Ultrasound Scanning
- Identify and manage open (not pregnant) ewes or does.
- Count fetuses to improve feeding management.
- Improve newborn survival through appropriate feeding management.
- Determine appropriate dry-off time in dairy animals.
Factors Affecting Ultrasound Scanning Accuracy
For producers to get the maximum benefit from pregnancy scanning, factors affecting accuracy need to be well understood. Some of the factors that seem to reduce accuracy of pregnancy scanning in sheep flocks include:
- full rumen (fresh off pasture)
- dirty sheep (in the crutch-udder area)
- fat animals
- prolific animals (lots of triplets, quads, etc.)
- extra-wild, jumpy lambs or yearlings
- too much variation from the 78-day ideal (below 55 and above 100 days)
- too many operations (marking, hand recording animal ID, drafting off scanned animals) and not enough staff.
Planning for Success
With good setup, a throughput of 100 to 150 ewes or does per hour is possible. To ensure a successful scan, consider the following tips:
- Book appointment as early as possible.
- Know dates of ram or buck entry and removal.
- Aim to scan between 70 and 90 days.
- Ask the scanner about their protocols and prepare your working area accordingly.
- Take sheep off feed in preparation.
- Have adequate labour available.
- Do NOT plan to do other jobs while scanning.
- Provide some means of equipment cleanup.
Cost-Benefit of Pregnancy Scanning
To demonstrate the cost-benefit of scanning, consider the example of a breeding group of 200 ewes, with a typical open rate of 5%. Ewes open at scanning can be culled immediately, taking advantage of seasonally strong cull prices, or moved into the next breeding group and exposed again for breeding. For the purposes of this example, cost of scanning is assumed to be $2.00 per animal. In many instances, the cost will be less than this, depending on travel distance and whether other flocks in the same area are being scanned at the same time. Scanning may be billed on a per ewe or doe basis or charged by the hour, depending on the scanner.
The revenues and costs used in this example were updated in 2021 based on consultation with service providers and Ontario Sheep Farmers’ Market Reports (5-Year Averages from 2016 to 2020). These figures are provided for illustrative purposes only.
Cost of scanning:
200 ewes @ $2.00 each = $400
Income from sale of culls:
5% open = 10 ewes @ 145 lb average weight and $1.25 / lb = $1,812.50
Feed Savings:
Feed savings, relative to normal culling time, can be calculated using the following formula:
Number of open ewes * number of days to lambing * pounds feed / ewe / day
Hay: 10 ewes * 60 days * 5 lb / day = 3,000 lb (1.36 metric tonnes)
1.36 metric tonnes @ $150 / tonne = $204
Grain: 10 ewes * 45 days * 1.5 lb/day = 675 lb (0.31 metric tonnes)
0.31 metric tonnes @ $200 / tonne = $62
Savings in Lamb Mortality:
Through better feeding management, singles will be smaller and multiple lambs will be larger. Reducing lamb mortality from 12% to 10% for a flock averaging 2.0 lambs born per ewe this will result in an extra 6 lambs in this sample flock. At today’s market prices, this reflects an extra $1,200 to $1,800 in gross income for the six lambs in our sample flock.
Conclusion
Ultrasound pregnancy scanning is a cost-effective management tool to improve breeding program management, feeding management, and newborn survival.
