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Pregnancy Scanning your Flock

It is important to know what ewes are in lamb, when they are due to start lambing and how many lambs each ewe is carrying. This information is vital for pre and post lambing management and involves scanning ewes as close as possible to 80 days post ram turn out, says Eamonn Dempsey, Teagasc Advisor

Scanning at 80 days

The decision on the correct time to scan is supported by recording the date breeding started and the use of raddle to enable identification of what ewes have been served and when they were served. Scanning at 80 days will ensure that the scanner can pick up all of the ewes that are in lamb. Ewes should be restricted from food for about 10 hours in advance of scanning to allow the ultrasound to accurately predict the number of lambs a ewe is carrying. The process of scanning itself is quick, stress free and can be carried out when the sheep is in a standing position in a designated crate.

Preparing for Scanning

In preparation for the scanning, make sure you have a good marking system to identify single, twin, triplet and barren ewes and whether they are early, middle or later lambing as will be detected or identified by the technician doing the ultrasound.

  • If you scan ewes that are greater than 90 days pregnant, it will be more difficult to identify how many lambs the ewe is carrying.
  • Equally if you scan a ewe before 80 days post ram turn out, there is a chance the scanner won’t give accurate results or may even identify a pregnant ewe as barren.

Scanning of early lambing flocks is carried out in October/November and the scanning of mid-season flocks is carried out in December but it is up to you to pinpoint the best possible date to achieve accurate scanning results and make arrangements with the Ultrasound Technician.

Using Scanning results

Scanning results can be used to increase flock productivity and profitability by grouping ewes on predicted litter size and appropriate nutrition to produce lambs of optimum birth weight and ensuring ewes have adequate colostrum for their new born lambs.

Not every sheep farmer pregnancy scans their flock, but once they start scanning they generally continue to do so as the benefits become clear.

Some of the benefits include:

  • identifying barren ewes that can be culled and sold
  • the total litter size is known in advance of the lambing season, and
  • ewes can be grouped according to number of lambs scanned to avoid under or over feeding.

Feeding the ewe in late pregnancy

In developing a nutrition plan for housed ewes in late gestation it is essential to carry out a representative forage analysis to determine its feed value, particularly dry matter digestibility.

  • Ewes carrying triplets should start concentrate supplementation 10 weeks pre lambing
  • ewes carrying twins should begin at 8 weeks pre lambing and
  • ewes carrying singles at 6 weeks pre lambing

– all starting off on 0.2kg of concentrates per head per day and increasing in line with recommendations as lambing approaches.

After scanning if there are twin bearing ewes behind target on body condition score, they should be penned with triplets and put on a higher plain of nutrition to help increase body condition.

Scanning is a cost effective management tool used in sheep production, it has numerous benefits which remove guesswork from pre-lambing management decisions.

The Teagasc Sheep Specialists and Teagasc Advisors issue an article on a topic of interest to sheep farmers on Tuesdays here on Teagasc Daily.  Find more on Teagasc Sheep here  Teagasc provides a Local Advisory and Education service to farmers. Find your local Teagasc office here