14 January 2025
Pregnancy scanning and making the best use of the results
January is the month during which many lowland sheep flocks will be getting their breeding ewes pregnancy scanned. Head of Sheep Knowledge Transfer at Teagasc, Michael Gottstein explains how pregnancy scanning interlinks with a number of important tasks.
These tasks include:
- Identifying which ewes are empty. Given current high sheep prices, there may be an opportunity to cull non pregnant ewes.
- Identifying pregnant ewes and the number of lambs that they are carrying.
- Identify the stage of the pregnancy and expected lambing date.
Pregnancy scanning is a relatively cheap and highly cost effective practice when the information is subsequently used to better target concentrate supplementation. The biggest financial benefit arises from a reduction in concentrate usage where ewes are fed according to litter size, body condition and target lambing date. This will require grouping ewes in late pregnancy into different groups based on litter size, body condition score (BCS) and lambing date. The table below outlines an example of how this can be practically achieved.
| Group | Animal type | Lambing date | Concentrate feeding regime |
|---|---|---|---|
| 1 | Triplet bearing ewes plus twin bearing ewes in poor BCS | First two weeks | Start feeding 8 – 10 weeks pre lambing |
| 2 | Twin bearing ewes plus single bearing ewes in poor BCS | First two weeks | Start feeding 6 – 8 weeks pre lambing |
| 3 | Single bearing ewes | First two weeks | Start feeding 4 – 6 weeks pre lambing |
| 4 | Triplet bearing ewes plus twin bearing ewes in poor BCS | Week 3-4 of lambing | Can be penned with group 2 |
| 5 | Twin bearing ewes plus single bearing ewes in poor BCS | Week 3-4 of lambing | Can be penned with group 3 |
| 6 | Single bearing ewes and all other ewes lambing after 4 weeks of onset of lambing | Week 3-4 of lambing | Commence concentrate supplementation four weeks after group 3. |
An example of how this would work for a mid-season lambing flock of ewes being fed 70% DMD silage could be as follows:
- 10 weeks pre lambing – commence feeding triplet and thin twin bearing ewes lambing to 1st cycle
- 8 weeks pre lambing – commence feeding twin and thin single bearing ewes lambing to 1st cycle plus triplet bearding ewes lambing to 2nd cycle
- 6 weeks pre lambing – commence feeding single bearing ewes lambing to 1st cycle and twin and thin single bearing ewes lambing to 2nd cycle
- 4 weeks pre lambing – commence feeding all other pregnant sheep.
When to scan?
The ideal time to scan ewes is between day 45 and 80 of pregnancy. From a practical point of view, it is generally recommended that scanning takes place 80 days post ram turnout. To aid the scanning operator to successfully identify the litter size of the ewes, it is a good idea to have the ewes fasted for eight to 10 hours prior to scanning. This is to reduce the area taken up by stomach contents.