Welcome to Signet on This page contains information provided by signet to give an overview of the benefits of performance recording to visitors of the site who will see "Performance Recorded" mentioned on many of the breeders pages.

As abattoirs and processors continue to demand carcases of higher quality, the ability to produce well muscled, lean stock at the correct weight is becoming increasingly valuable. 
Sheepbreeder uses performance recording and statistical analysis to calculate Estimated Breeding Values (EBV's) and Indexes that provide the farmer with an objective method of comparing the genetic potential of different animals.  Indexes are tailored to suit the breed of sheep, breeder objectives and industry requirements.

Pedigree breeders need to continually select using performance recording or risk being left behind. Commercial producers are increasingly aware of the benefits that can be gained from buying Signet recorded rams and recorded females.
To help terminal sire breeders improve several traits at once an index is calculated for each animal by combining the EBVs for Scan Weight, Muscle Depth and Fat Depth.

Ultrasound Scanning to assess Muscle and Fat Depth

A key element of performance recording of sheep through the Signet Sheepbreeder Service is the collection of accurate measurements of muscle and fat using ultrasound scanning machines. This technical note explains the procedure used to collect muscle and fat data using an ultrasound scanning machine to the standard required when using the Sheepbreeder Service.

All scanning technicians providing scanning information for Signet Sheepbreeder recording are trained by Signet staff and are required to pass AHDB tests for accuracy and repeatability through the scanning of live lambs and the measurement of their deadweight carcases within 24 hours. 

Lambs are scanned at approximately 21 weeks of age, although some earlier maturing breeds, such as the Hampshire Down, can be measured from 18 weeks onwards if they are on an intensive diet.

The most important factor when scanning lambs is to ensure that there is sufficient variation in the muscle and fat depth measurements. This usually requires animals to be at least 45kg and in reasonable body condition. In situations where lambs are growing more slowly it is perfectly acceptable to scan them at an older age to ensure that sufficient levels of variation can be detected.


A weight on the scanning day must also be recorded.  Ideally, lambs should have been managed as one group to ensure the largest contemporary comparison groups.  Where management has been different, group numbers must be allocated to the animals to record which lambs are managed in the same way. 

The scanning technique involves parting the wool at the third lumbar vertebra at 90 degrees to the backbone and then applying liquid paraffin oil to give contact.  The third lumbar is relatively easy to find by counting three transverse processes back from the last rib, noting that the first spinal process is often very close to the last rib.

The transducer is placed on the prepared site and adjusted until a clear image of the third lumbar transverse process, the eye muscle, and the fat layers can be seen on the machine’s screen.  It is very important to identify all the fat layers and have a clear muscle depth.  The picture is then frozen and linear measurements of muscle and fat depths taken on the screen using a cursor. 

A single measurement is taken of muscle depth at the deepest point and three measures of fat depth are taken at 1cm intervals.  The first fat depth measurement is taken above the muscle deepest point and the following two measurements taken at 1 cm intervals from this point further from the backbone.

Measurements are taken in millimeters to one decimal point. A typical range of fat depths would be between 0.5 – 8mm. Eye muscle depths would typically fall within the range 20 to 36mm, with a few of the biggest terminal sires on intensive diets achieving measurements up to 40mm.

For further details or to start performance recording your flock contact
AHDB, Signet Breeding Services
Stoneleigh Park, Kenilworth, Warwickshire, CV8 2TL
Tel: 0247 647 8826 Fax: 0247 641 9071 
Email:  www.