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CT Scans Used To Spot Pigs With The X Factor

by 5m Editor
6 May 2007, at 12:00am

By Dr. Grant Walling, JSR Genetics. Selection by pig geneticists has traditionally focused on traits relatively easy to measure on the live animal, for example growth rate.

Such improvements have benefited producers as the breeding stock they purchased has been selected on such traits. However, with the industry becoming more focused towards packers and retailers, they too want to see improvements in qualities affecting the economics of their businesses.

X-ray Computer Tomography (CT) is a technology many will be familiar with from hospitals. It allows cross-sectional images to be produced from a living animal (see above). The image is produced using information gained from the absorption of a low dosage X-ray beam that passes through the pig from all angles around the body. This allows the identification of different types of tissue, as dense tissue (such as bone) appears light and less dense tissue (such as air in the lungs) appears darker.

A series of scans on a pig provides a very accurate prediction of the carcase composition. The improvement in prediction of carcase muscle, fat and bone is 6.4, 5.6 and 15.0% respectively when compared with more conventional ultrasonic techniques. Of greater benefit to the processing and retail sector is the ability to be able to differentiate muscle yield within the different primal cuts (loin, ham, belly and shoulder).

The heritability of the CT muscling traits is moderate-high (typically around 40%) and so suited to genetic improvement. More recent work with CT scanning in the sheep sector has suggested a methodology for the selection of meat quality using measures of muscle density. Without this technology, breeding companies have previously had to use carcase dissection data. The downside of such techniques is the necessity to slaughter animals prior to data collection. CT scanning is able to collect the valuable information on live animals (under anaesthetic), which can then be used for further breeding.

Conventional selection schemes ensure that JSR boars meet the high criteria required by producers. This new technology is allowing JSR to scan all AI boars prior to entry into the AI studs, providing the processing and retail sectors with information that ensures only the most suitable boars are used in their supply chains.

Although originally developed to benefit human medicine, CT scanning is now a useful tool for a healthy pig industry.

April 2007