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Coopworth 'Muscle Bus' On The Road

Fuseworks Media
Fuseworks Media
Coopworth 'Muscle Bus' On The Road

Earlier this year a steady stream of Coopworth ram hoggets from registered Coopworth studs throughout New Zealand have taken a short break off farm at Lincoln University.

No, the farmers aren't sending them on holiday; their trip on board the colloquially named 'muscle bus' has a serious purpose.

While away, the muscle, fat and bone content of each ram is assessed using the non-invasive technology of computed tomography (CT scanning).

Market signals are demanding high yielding carcasses within defined weight ranges. Animals that meet these defined criteria are able to attract payments based on saleable meat yield. Desirable carcasses should have a high proportion of muscle throughout the carcass compared to bone and fat.

Coopworth breeders have recognised the need to identify animals with high meat yield and have undertaken to utilise all available technology to identify individual animals and sire lines that are genetically superior for meat yield. This provides the opportunity for breeders and their commercial clients to take advantage of the yield payment systems being put in place by processing companies. CT scanning allows farmers to accurately identify the best animals in the flock for breeding based on extremely accurate predictions of muscle, fat and bone.

"The greatest economic benefit for commercial farmers from using CT scanning in a sheep breeding programme is as part of a two-stage selection process based on ultrasound and CT," said Nigel Jay, Senior Technical Officer in the Agriculture Department at Lincoln University who is in charge of the CT scanning.

"This method of selecting for composition in cuts can be more beneficial than selection based on progeny testing alone and can accelerate breeding programmes to assess carcass fat and muscle weights, because more objective information is obtained and analysed," he said Farmers are advised to use ultrasound to assess a large number of animals and then select the top 10-15% for scanning.

In CT scanning low dosage x-rays are emitted in a circular motion round the animal, detectors on the opposite side measure the amount of absorption of x-rays, which depends on the differing density of tissues that they pass through. A two-dimensional picture is created based on the different tissue densities.

Currently at Lincoln University sheep are scanned at four places, one in the chest and hind leg and two in the loin. Images are high resolution and this allows detailed descriptions of body composition to be made. Prior to CT scanning, this information could only be obtained after slaughter or by subjective eye appraisal.

"Our results have been shown to give a highly accurate prediction of quality of the final carcass," said Nigel.

"For breeding purposes, the only way to objectively measure hindquarter muscling on a live animal is by using the CT scanner. While ultrasound measures muscle and fat in the loin region, the CT scanner measures the weight of muscles and fat across the whole carcass."

The purchase of an upgraded CT scanner in 2007 has expanded Lincoln University's capacity and allowed it to offer a commercial service to Coopworth farmers throughout New Zealand.

Strict animal health and welfare standards are adhered to while the sheep are away from their home farms.

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