Improved detection of multiple foetuses

Valuable information can be collected by pregnancy scanning ewes for multiples. This information can be used to help improve lamb survival and increase profitability.

Using electronic identification devices (EID) helps make the collection process faster and more accurate, creating individual fertility data for the ewe’s lifetime. Understanding the benefits and potential issues will help you to ‘scan for success’ next season.

Why should I scan for multiples?

Scanning for multiples can help you to make decisions based on an individual ewe’s performance. This means you can tailor management and production systems according to pregnancy status, which can lead to improved profitability of the sheep enterprise.

By scanning for multiples, you will be able to:

• tailor your twin- and single-bearing ewe management, in particular, their different energy requirements. Lifetime Ewe Management recommends that twin-bearing ewes should be 0.3 of a condition score higher than single-bearing ewes at lambing. This can improve lamb survival rates and minimise dystocia, by optimising the birth weight of both twin and single lambs
• be more flexible in poor seasons or in adverse conditions, by prioritising resources (feed, shelter and labour) to the different groups of ewes. Managing ewes according to their scanning data means you can allocate lower feed paddocks to single bearing ewes and consider reducing mob size for twin or triplet bearing ewes
• plan for the future with good baseline data on number of foetuses present at scanning. When combined with your expected lamb survival rates, this can be used to estimate likely lamb marking results and therefore plan sale numbers. It also allows for identification of losses later in the reproductive cycle
• identify ewe fertility at a given point in time, which some people use to class groups of ewes for marketing, for example scanned-in-lamb (SIL) and not-station-mated (NSM)/empty ewes.

Things to consider are:

• 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, smaller mobs of ewes. This could require investment in infrastructure (temporary fencing, water) as well as labour, depending on your current set up
• if twins are lambed in large mobs or under high stocking rates, there is increased potential for mis-mothering. If this is the only management option you have, it is important to keep this in mind
• scanning for multiples is significantly more beneficial than SIL or empty scanning, so long as the ewes are managed differently or the information is recorded for future use. While this is good to do, the real benefit is from differently managing the ewes based on their pregnancy status
• encourage contractors to ‘come clean and go clean’ in line with your farm biosecurity plan, and ensure they fill in your visitor log.

Using EID in pregnancy scanning

Victoria currently has a significant 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.

Using EID to collect data means that:

• multiple traits can be recorded simultaneously, for example the number of foetuses and age of foetus (early or mid/late or first and second cycle)
• traits that indicate reproductive performance can be recorded across the production cycle, for example condition score at joining, pregnancy scanning and lamb rearing results across years. This can help to identify the ewes that meet your breeding objective
• data collection is faster and more accurate compared to extra drafting or marking ewes, and a permanent record of the data is created, without the use of temporary sprays or raddle. If drafted mobs get mixed, EID records can be referred to for redrafting.

Potential barriers to using EID for data collection are:

• 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 loan items if you don’t intend to use the equipment for other things. Having someone that can operate the technology present on scanning day is essential.

How to scan for success with EID

Following these simple tips will result in an optimal scanning image, an efficient process and sound animal welfare practices when pregnancy scanning ewes.

Joining

Join for no more than two cycles (35 days) to optimise scanning accuracy. Ensure joining dates are correct, and rams have not had access to the ewes outside of the planned joining period.

In cases where an extended joining period is necessary, rams should be removed after two cycles for a period of two weeks before being rejoined. Pregnancies in this second joining period can then be identified on a follow-up scan.

At removal of rams from the joining mobs, contact the contractor to book in scanning, so the ideal date can be identified, and the contractor’s travel costs may be minimised. Also arrange with the contractor who will supply the EID equipment and discuss their equipment/crate set up.

Scanning

Ninety days after the ram has been introduced is the optimum timing for scanning for multiples, although it can be done from day 80 through to day 100. Shading caused by developing bones reduces the accuracy of scanning for multiples after day 100.

Ensure ewes are off feed and water for at least 4 hours before scanning and are not given any supplements (for example grain, hay, silage) the day before scanning. It is important that scanners can set up in good yards, and that there are enough people to ensure a steady flow of ewes to the scanning crate.

If supplying EID equipment, ensure that it is fully charged, with spare batteries or alternate power sources available if necessary.

Collecting EID data at pregnancy scanning

Contractors can link the EID tag and pregnancy status whilst the ewe is in the crate. This is the most efficient and accurate method if all ewes are electronically tagged. It is simple to collect multiple traits using this method.

Ensure that the next sheep’s EID tag is not read until the current ewe’s scanning result is recorded. Reading tags out of sequence will affect the accuracy of the records. This can be avoided with correctly tagged animals, crate functionality and good yard design to ensure only one sheep is in the crate at a time.

Some data collection systems can be programmed to require a linked EID tag and trait result before accepting the next tag.

Collecting EID data post pregnancy scanning

The alternative to collecting data at point of scanning is to identify scanning results via draft or visual markers (spray/raddle) and then record the traits against EID tags once pregnancy scanning is completed.

Using a gate to draft ewes into groups based on pregnancy status can be particularly useful when the contractor does not have EID capability or when a significant number of ewes to be scanned are not electronically tagged. However, if groups are accidentally mixed in the yards before data is recorded, information collected during pregnancy scanning will be lost.

It is also challenging to record foetal age unless a system of spray/raddle marks is used or ewes are drafted in many directions.

It is important when collecting data post scanning to be mindful of the ewes’ total time off feed/water and consider time and labour implications.

More information

• Australian Animal Welfare Standards and Guidelines for Sheep 2016
• Making More from Sheep Procedure 10.2: Managing your ewes to improve lamb survival
• Sheep CRC Practical Wisdom PW1.3 Reproduction Series and PW1.5 Precision Sheep Management
• Lifetime Ewe Management course, coordinated by Rural Industries Skills Training (RIST)
• Lambing Planner tool. DAFWA, also available in App format.

Acknowledgements

Produced with funding from Meat & Livestock Australia Donor Company project EID enabled.