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Pregnancy Scanning Ewes

Key Points

  • Scanning assists in making informed management decisions
  • For wet/drying, scan 35-40 days after rams have been removed
  • Possible to scan up to 400 ewes per hour
  • Considerable benefits from scanning for multiple births

 

PREGNANCY scanning of ewes has become an important tool in managing reproductive performance in ewe flocks. It enables producers to make informed management decisions that will improve productivity and profitability of their sheep enterprise.

The benefits of scanning include the ability to identify and manage ewes according to their pregnancy status. Dry ewes can be sold, remated or stocked at higher rates. Single and multiple bearing ewes can be managed according to nutritional requirements and enable optimisation of pasture/feed. It enables producers to calculate lamb losses between scanning and marking and also measure the reproductive potential of their ewe flock. An increase of 10% in lambing percentage equates to a considerable increase in profits.

Ultrasound scanning of ewes is a simple process; all a producer requires is a standard race setup and two people to assist. Depending upon individual setups it is possible to achieve a throughput of up to 400 ewes per hour; this is less when scanning for multiple pregnancies. It is recommended that scanning is done 35-40 days after rams have been removed (for wet/drying and based on a 42 day mating period). Best results for multiple scanning are 80-100 days from the commencement of joining. An optimal scanning time calculator is available at Cousins Merino services website.

Accuracy of scanning is important as this will determine the benefit to the producer. Factors known to affect accuracy include ewes not kept off feed the night prior (full rumen), extended joining periods, inadequate staff, fat animals and incorrect joining dates.

Research has demonstrated that scanning for multiple births is where considerable benefits can be gained. Scanning for multiple’s enables the twin bearing ewes to be managed accordingly and supported through increased nutrition through placement on best pasture and/or supplements and shelter belts.

It is important to be aware that lamb survival is a major factor in reproductive efficiency. Scanning ewes is only a measurement of the potential of the ewe flocks reproductive ability. Nutrition is possibly the most important factor in ensuring that the potential of the ewe flock is achieved, however the lifetime wool project in sites in Victoria has demonstrated that despite optimal ewe nutrition the twin survival rate was still only 56-67%.

Individual benefits from scanning reported by sheep producers include finding out that rams didn’t work during hot weather; on scanning only 20% were in lamb creating a potential lambing disaster if ewes had not been scanned. In this instance rams were put back out with the ewes and rescanned later with considerably better results. Individual producers were able to achieve an increase in lambing of up to 20%, which would of otherwise been an opportunity missed.

Producers are no longer limited by the inability to know how many lambs ewes are carrying prior to lambing. Real time ultrasound has enabled producers to make significant advances in flock management and improve lambing and lamb survival rates.

DETAILS: Michelle Cousins, Cousins Merino Services, 0407 607 899

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