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ARTICLES >> Livestock Articles

Scanning Ewes makes 'Cents'

Posted by Bestprac on Feb 02 2012

By Geoff Duddy, Livestock Officer (Sheep & Wool), Industry & Investment NSW
It is estimated that around 32% of the national ewe flock are scanned annually with an increasing number of producers now identifying litter size.


This increase has initially been driven by producers targeting feed cost savings during the drought. More recently, producers have recognised that improved twin-bearing ewe nutrition can lead to significant improvements in lamb and ewe survival, marking percentages, wool quantity and quality and marketable lamb numbers.

Sheep producers considering scanning for this year’s lamb crop need to plan to have scanning operators on-farm between 70 to 100 days after rams were first introduced to the ewe flock. Where rams are joined for 6 weeks the optimum timing is around 90 days after ram introduction.

Identifying dry, single and multiple bearing ewes will cost slightly more (~70c/hd depending on flock size, travel etc) than simply identifying ‘wet’ and ‘dry’ ewes (~45c/hd). Scanning for multiples is recommended as potential gains that can be made in terms of feed budgeting, lamb and ewe survival and productivity and profit margins generally usually far outweigh costs incurred.

Plan to scan the ewe flock 70 to 100 days after rams were introduced to the ewes (day 1 of a 6 week joining). This period coincides with rapid development of the placenta - the ‘lifeline’ for the developing foetus(‘s). Research has shown that improvements in nutrition, particularly increased protein intake, during the second trimester will significantly increase placenta size and ultimately benefit twin foetus development. This usually leads to improvements in twin-born lamb birth weights and improvements in lamb vigour, suckling and survival.

In self replacing merino flocks, scanning and improved ewe nutrition has been shown to lead to improvements in lamb(s) lifetime fleece weight (+0.2 kilograms) and fibre diameter (a reduction of up to 0.4 microns finer fleeces) compared to ‘poorly’ fed foetuses. Given that many twin born lambs are ultimately culled due to slow growth rates and/or poor wool traits, long term improvements in flock reproduction rates may also be affected. Culling underfed twin born lambs means you may be culling your (potentially) more fertile future breeding ewes!

Improvements from scanning can include increases in stocking rates and lambing percentages by 14-15% and reduced ewe mortalities by up to 44%. When we also factor in improvements in wool quality/value the cost of scanning and target feeding twin bearing ewes is easily recouped.

With sheep meat, wool, breeding ewe and skin values at record highs, the use of ultrasound to accurately identify dry ewes (for rejoining or sale) and pregnant ewes into low (single) and high (twin bearers) ‘feed need’ management groups makes sense economically.

Industry and Investment NSW ( and Sheep CRC ( websites have numerous publications that can assist producers interested in utilising fat scoring, nutritional management and scanning in an effort to improve lamb survival.

A list of scanning contractor contacts is also available 


Last changed: Feb 06 2012



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