Making use of ewe pregnancy scanning data

// Rearing and Weaning

Ewe pregnancy scanning is underway in most regions, and the resulting data can help farmers make informed management decisions in the lead up to lambing to help maximise lamb survival.


Using scanning data

  • Scanning allows targeted management.
  • When combined with tailling tallies, scanning data can identify which paddocks favour lamb survival.
  • There can be up to a 50-day difference between early and late lambing ewes. Scanning identifies early and late lambing ewes so feed can be allocated accordingly.
  • Set-stocking all ewes at the same time can mean later-lambing ewes are consuming feed that could be saved for lambing and lactations.

Speaking on a Beef + Lamb New Zealand podcast, Massey University’s Dr Paul Kenyon outlined the many benefits of scanning. These include the ability to sell dry ewes early, identifying early and late lambing ewes and allowing the targeted management of multiple-bearing ewes.

Dr Kenyon said that scanning percentages and lamb survival are key drivers of farm profitability, so knowing how many lambs their ewes are carrying will allow farmers to target their management accordingly.

When used in conjunction with scanning data, stocking rates and pasture covers can be manipulated to help maximise lamb survival and pre-weaning growth rates.

Paddocks grazed early in the winter rotation will likely be the most suitable for lambing poor condition, multiple-bearing ewes as they should have the highest pasture covers. This feed will aid lamb survival and allow ewes to gain body condition after lambing.

Scanning information, when combined with tailing tallies, can also give farmers an understanding of which paddocks most favour lamb survival.

Using scanning data, farmers will know exactly how many potential lambs are going into a paddock at set-stocking and when correlated with tailing tallies, farmers can get a good understanding of lamb survival.

“That’s a very powerful data set. When combined over a few years you have, for your farm and your environment, an idea of your best lamb survival paddocks and they may not be the ones you think they are. You can then make informed decisions about what ewes go into which paddock at lambing.”

Dr Kenyon says the ideal time for scanning is between 45 days and 100 days after the ram has gone out and it is also an ideal opportunity to Body Condition Ewes.

With multiple-bearing ewes, there is only a small window during which they can gain body condition, it then becomes physiologically impossible for her to gain condition due to the demands of pregnancy.

The foetus grows rapidly in the last 30–40 days of pregnancy and multiple-bearing ewes simply cannot eat enough to meet their demands, so she needs to draw on her body reserves. This is why targeted feeding in early to mid-pregnancy is so important.

For farmers breeding over three cycles, there can be a 50-day difference between the early and late lambing ewes and their respective nutritional demands will be very different.

Dr Kenyon says he is not advocating farmers run a large number of different mobs in the lead up to lambing, but suggests running two to three mobs and thinking carefully about which ewes need to be in which mob.

For example, early lambing, single-bearing ewes can be run with the later lambing ewes for a while because they have a greater ability to buffer feed challenges.

“Think about the risk that each ewe is under from not being fed well enough and being forced to use her body reserves or being stopped from gaining body reserves after lambing.”

Even when the vast majority of ewes are multiple-bearing, scanning can help identify early and late lambers so feed can be allocated accordingly.

“We never have enough feed on our farms over winter so why feed the early and late-lambing ewes the same?”

Set-stocking all the ewes at the same time can mean later lambing ewes are consuming feed that would be better saved for lambing and lactation. 

Find out more

Listen to this podcast on the use of ewe pregnancy diagnosis (scanning) information, with Professor Paul Kenyon, Massey University.