Why should I scan for multiples?

Scanning for multiples can help producers to make decisions that better address individual ewes’ requirements, rather than the mob average.

By scanning for multiples, you will be able to do the following:

• Tailor your twin- and single-bearing ewe management, considering their different energy requirements. Managing ewes using scanning data means that you can allocate lower-feed paddocks to single-bearing ewes and consider reducing mob size for twin- or triplet-bearing ewes. Targets for merinos and maternal ewes (see accompanying article) are that twin-bearing ewes should be 0.3–0.6 of a condition score higher than single-bearing ewes at lambing. This can improve lamb survival rates and minimise dystocia, by optimising the birthweight of both twin and single lambs.
• Be more flexible in poor and good seasons, by prioritising resources (feed, shelter, labour) to the different groups of ewes. In some seasons, it will provide selling (or buying) opportunities to manage the feed and cash resources you have available.
• Plan for the future with good data on the number of lamb fetuses present at scanning. Combined with your expected lamb survival rates, this can be used to estimate likely lamb marking results and therefore plan sale numbers. It also helps to identify where losses may occur in the reproductive cycle.
• Identify ewe fertility at a given time, which can be used to class groups of ewes for marketing.

Things to consider

• Running ewes based on pregnancy status can be more labour intensive, with more mobs to manage. You may also need to plan your paddocks to cope with more, but smaller, mobs of ewes. This could require investment in infrastructure (temporary fencing and water) and labour, depending on your current set-up.
• If twins are lambed in large mobs or under high stocking rates, there is increased potential for mismothering. It is important to keep this in mind if this is the only way you can manage your mobs of ewes.
• Scanning for multiples is much more useful than scanning for dry ewes only if the ewes are managed differently or the information is recorded for future use. For example, the number of fetuses can be used to estimate the number of lambs present at marking. Although this is good to do, the real benefit is from differently managing the ewes based on their pregnancy status.
• Contractors should be encouraged to ‘come clean and go clean’, in line with your farm biosecurity plan. They should also fill in your visitor log.

Using electronic identification in pregnancy scanning

Victoria currently has a number of pregnancy scanning contractors that offer individual animal recording using electronic identification (EID) technology.

You can also record pregnancy scanning results using your own EID collection equipment.

Why use EID to collect data?

• Data collection is quicker and more accurate than extra drafting or marking ewes, and a permanent record of the data is created, without the use of temporary sprays or raddles. If drafted mobs get mixed, EID records can be referred to for redrafting.
• Multiple traits can be recorded simultaneously – for example, the number of fetuses and their age (early/mid/late or 1st/2nd cycle).
• Traits that indicate reproductive performance can be recorded across the production cycle – for example, condition score at joining and pregnancy scanning, and lamb rearing results across years. This can help to identify the ewes that meet your breeding objective.
• Potential barriers to using EID for data collection
• Recording of pregnancy status can be slower if some of the ewes don’t have EID tags. If untagged animals are present, have a plan to apply tags efficiently. This will help maintain a smooth flow of sheep.
• EID equipment such as a panel reader and indicator can be expensive if used infrequently. Consider using your contractor’s equipment or borrow items if you don’t intend to use the equipment for other things. Having someone who can operate the technology present on scanning day is essential.

How to scan for success with EID

For further information

• Making More from Sheep – Procedure 10.2: Managing your ewes to improve lamb survival
• Lifetime Ewe Management course, coordinated by Rural Industries Skills Training Ph: 1800 883 343
• Lambing Planner tool, Western Australian Department of Primary Industries and Regional Development