Pregnancy scanning for ewes

Pregnancy scanning ewes

Scanning is a highly valuable tool to identify pregnant and dry ewes in a flock. The ewes that are in lamb can then be preferentially managed, and there is the option to sell, rejoin or retain dry ewes for wool production. 

The use of ultrasound technology to identify a ewe’s pregnancy status and/or litter number has contributed improved lamb survival within both wool and crossbred lamb enterprises.

Scanning can assist with management decisions in terms of: 

• Which ewes to feed and your projected feed requirements (pasture and supplements)
• Which ewes to sell
• When to start a feeding program,
• What feed quality is needed
• The differential management of dry, single and multiple bearing ewes prior to lambing.

The benefits of scanning ewes

In dry seasons, scanning results for spring joined flocks can often be lower than expected with low conception rates, high dry ewe numbers and low twinning rates 

In general, the higher the dry ewe percentage in a flock, the greater the benefit from scanning.

As the scanning rate (foetuses/100 ewes) increases, the benefit of scanning for multiples and managing these ewes separately increases compared to the benefit of scanning for just pregnant versus non-pregnant ewes.

Scanning and differential nutritional management of ewes based on pregnancy/foetal number can help improve:

• ewe and lamb survival rates
• ewe wool quality and cut
• progeny lifetime wool quality and cut
• lamb muscle development and growth rates
• placental development
• udder development
• milk production and quality
• flock fertility
• production efficiencies
• classable ewe numbers
• saleable lambs, breeding ewes and/or mutton.

It will also assist in the reduction of:

• supplementary feed costs (through targeted feeding of supplements to those ewes most in need)
• enterprise production costs.

The value of scanning also increases if poor seasonal conditions and/or drought occurs. Targeted paddock selection and/or strategic feeding of multiple bearing ewes to improve ewe/lamb survival and their life-long productivity have positive benefits to cost outcomes.

Recouping cost of scanning

Scanning costs vary with location and scanning choices (in other words, scanning for wet/dry, multiples, early/late). There is also additional handling costs associated with scanning, which include mustering and labour for the scanning procedure.

There are many ways that the cost of scanning is returned. These include:

• saving feed costs
• greater pasture for pregnant ewes
• improved flock fertility (a maiden ewe that isdry will rear 10-15% less lambs/year)
• increased value of lambs as there is less chance of long-term effects of poor nutrition during pregnancy. 

Effects of poor nutrition during pregnanacy can include:

• slower growth
• less muscle development
• compromised immune system
• lower adult reproductive performance.

The potential income from selling dry ewes will vary with scanning percentage. Ewes could be sold on the restocker market as breeders or directly over the hooks.

It is important to remember that selling dry ewes will reduce flock numbers and alter flock structure, which needs to be included in a flock management plan. It is evident that the lower the potential scanning percentage is, the greater the importance of scanning. Scanning pays no matter the season as it allows more accurate management of a flock’s production cycle.