Live animal ultrasound scanning is a non-invasive technology that enables producers to assess the carcase merit of individual animals while they are still alive. This allows valuable carcase information to be collected without relying solely on chiller data.
When used in conjunction with abattoir carcase data, ultrasound scanning provides an effective tool for identifying animals with superior genetic merit for carcase yield and quality traits, supporting selection decisions aligned with modern breeding objectives.
Recording Live Animal Ultrasound Scanning
The Australian Wagyu Association (AWA) encourages members to collect ultrasound scan data using an accredited ultrasound scanning technician. Be sure to ask your technician for their credentials, and accreditation number, to ultrasound scan animals for the purpose of genetic evaluation.
Scan data submission is the responsibility of the breeder not the Accredited Technician. Animal ID and scanning information should be entered into the Performance Template.
Completed templates should be submitted to the AWA performance email for processing and inclusion in the WBV analysis.
What is measured?
The carcase traits commonly measured include:
- Rump Fat Depth (P8 Site) – Measured at the P8 rump site. Reported to the nearest millimeter (mm).
- Rib Fat Depth – Measured at the 12/13th rib on the longissimus dorsi (eye muscle). Reported to the nearest millimeter (mm).
- Eye Muscle Area (EMA) – Measured as the cross-sectional area of the longissimus dorsi between the 12th and 13th ribs. Reported in cm². Also referred to as Rib Eye Area.
- Intramuscular Fat (IMF) – Measured using a longitudinal ultrasound image of the longissimus dorsi between the 12th and 13th ribs. Reported as a percentage (e.g. 3.5%).
When Should Animals Be Scanned?
Animals can be scanned between 300 and 800 days of age, with most scanned as yearlings or rising two-year-olds (around 600 days). Animal body condition is the most important consideration when determining the timing of scanning.
As a guide:
- Minimum average rump fat depth of 4–5 mm
- Minimum average rib fat depth of 3 mm
- For ultrasound technologies commonly used in Australia, IMF results are generally optimised when most animals fall between 2–8% IMF. Some international systems may accurately assess a broader range of IMF levels.
Animals should ideally be on a rising plane of nutrition prior to scanning to ensure sufficient variation within the group.
Which Animals Should Be Scanned?
While bulls are most commonly scanned, it is recommended that heifers are also scanned:
- Heifers-as they mature earlier and often better express genetic differences for IMF
- Steers-where practical, as they provide useful information for sire and dam evaluation
Scanning a whole contemporary group of animals improves the accuracy and reliability of Carcase WBVs.
Helpful Hints:
- Scan all within each management group.
- Do not submit data for only a selected portion of the group (e.g. sale bulls only), as this may result in biased WBVs.
- Record all animals in a contemporary group on the same day.
- Assign separate management groups where animals have been treated differently (e.g. supplementation or varying pasture conditions).
- Only one set of scan measurements per animal is used for analysis.
