CT scanning to determine sheep meat quality
INNERVISION runs a CT scanner for use specifically on animals and for other ‘non-human’ applications in the primary industries.
Dr Neville Jopson talks through the journey of INNERVISION to develop a protocol and computer application to improve the evaluation of meat quality and yields for ram breeders.
Operations Manager Wendy Bain explains some of the practical considerations involved in CT scanning sheep.
Transcript
Roger Bourne
Seeking better technology to help determine sheep meat quality and yield, Landcorp later Pāmu and AgResearch teamed up in the mid 1990s to form the joint venture INNERVISION. They introduced the first dedicated CT scanner for agricultural application in New Zealand, installing it at the Invermay Research Centre in Mosgiel. The CT scanner uses rotating x-ray machines to produce images and a computer to piece those images together. The technique now not only continues to add to the profitability of Pāmu farms, but tries other agricultural research as well.
Dr Neville Jopson
It’s a human CT scanner, it’s the same as you’d find in any hospital. What it does is it looks inside animals and samples and so we’re able to measure in a live animal the amount of meat, fat and bone or any object inside that we’re interested in looking at.
Ultrasound is real time, so we can actually see things moving but it can only penetrate a certain depth – about 10-15 cm into an animal. So when it’s used in animals we scan at a site where the muscles are very close to the surface and they're a high value, but we only sample one part of the animal. With CT we can measure the entire animal, we can place the scans wherever we like. It’s not real time, so we need to sedate the animal and also it doesn’t move. So we have to bring animals to the scanner, rather than the scanner to the animals. But the quality of the images is much better and it gives us a much more accurate result.
In the stud breeding industry, we’ve made fantastic progress in terms of genetic improvement using ultrasound. It’s, it’s moderately accurate, it’s nowhere near as accurate as CT, but in genetic improvement if we can measure a lot of animals with a moderately accurate thing we can make fantastic progress. And so we’ve moved the sheep industry – in terms of improving carcass at an enormous distance using ultrasound and also for research purposes we would actually slaughter animals and sit down and dissect them. So it replaces that, it means we don’t need to run as large experiments. It means that we can turn them around much faster and we’ve got a live animal at the end of it.
Wendy Bain
I first met Neville back in 88/89 when he came to do his PhD in imaging, around images and CT scanners and he finished his PhD and then came back at about 1992 when this technology was moving throughout the industry, throughout different countries and Neville came back to set one up at AgResearch.
Rams need to be used the same year that they're CT scanned, so the breeders will ultrasound the animals and then they'll select their top percentage and they'll come for CT scanning. There’s a really quick turnaround time. So we like to scan about that 50 a day – that might take us… we do 10 an hour, that’s a good rate. So five hours of scanning and an hour either side and then getting the data off and onto the PC. All the images have to be processed, so they have to be actually dissected with a paint programme, taking out all the non-carcass, leaving just all the yield and then they get run through other programmes that convert them to weight of yield in the three primals. So time is of essence in that respect because we need to get the results into the National Genetic Evaluation system for the breeders then to select their animals out of that evaluation.
Dr Neville Jopson
So this is the image that comes off the CAT scanner so we just want the carcass, so we want to turn it into this image here. So this here shows the bits that we need and that’s a very time-consuming process, so just… when we scan we’ve got a daunting number of images that we’ve actually got to go through and remove the non-carcass components. So that’s the bit that we’ve taken all of the processed images and married them up with the original images and train the machine to be able to do that step for us.
This is the CT image, it’s of a live animal so we’ve got the rectum and we’ve got other parts that we don’t want. This is the processed image that we actually use. The black-and-white images that you've seen are an intermediate step that just identify the carcass and produce this image. This is the carcass alone which is the information that the farmer needs because that’s what he actually gets paid for. He doesn’t get paid for producing a large gut, or lots of internal organs, it’s just the carcass. So this is the thing that we measure and the result that we return to the farmer.
The high-value cuts are the loin, the hindleg is the next most valuable part and the shoulder is the least valuable of all of them and there are differences between them. So we are able to select animals that have, perhaps, more in the higher priced cuts. Also we’ve had enormous changes in our carcasses – the things that we’ve selected on has changed over time. So initially we were very much about removing fat, now there is benefits in having fat in different parts of the carcass. So having intramuscular fat – fat between muscles – adds quality to the meat. So the flavour comes from fat. Also the, the types of fat are different. There are more unsaturated fats in the intramuscular fat. So healthier fats and those things and having some fat there is a great value in terms of improving the quality of that product. So being able to select for that is sort of the next challenge for us.
It’s made massive changes over the 30 to 40 years. So when I started, we were producing around about a 15 kilogram carcass – and it was set at that because if we took them bigger they’d have too much fat. And they’d come from carcasses that were only 13 kilograms where now our carcasses are around about 19 kilograms and they are leaner than the animals that we were killing at the 13–15 kilogram carcass weights. So the amazing thing about the sheep industry that sheep farmers should give themselves a pat on the back, is that we’ve gone from having 80 million ewes to about 28 million ewes. They are much more fertile, so they're having more lambs, they're going to greater carcass rates. So over that period we’ve maintained the same weight of export product. So we’re producing the same amount of lamb off a much smaller number of ewes. So we’re much more productive and producing a much higher quality product.
Acknowledgements Video clip courtesy of Showdown Productions.
