A review of non-invasive techniques to measure livestock body composition
The July Article of the Month is an invited review entitled ‘Non-invasive methods for the determination of body and carcass composition in livestock – Dual Energy X-Ray Absorptiometry, Computed Tomography, Magnetic Resonance Imaging, and Ultrasound: invited review’
The ability to accurately measure body or carcass composition is an important application for farm animal breeders, producers, abattoirs, butchers, meat (and fat) processors. There is always a need to exactly know the performance of breeding animals and for example of their offspring or other related animals for further improvements in terms of consumer needs. Abattoirs or butchers need exact information on carcass composition including meat and fat quality, again in order to meet consumer needs and in order to have a measure for a fair payment to producers.
Non-invasive techniques are required for both performance testing of the live animal and carcass grading or classification in order to do no harm to the live animal and to cause no damage on the carcass. Advances in especially non-invasive techniques are mainly based on the development of electronic and computer driven methods in order to provide exact and objective data for the farm animals or carcasses in interest.
The preference for a specific technique depends on the target farm animal species or carcass – combined with technical and practical aspects like accuracy, reliability, cost, portability, speed, ease of use, safety, and for measurements on the live animal the need for fixation or sedation. The techniques rely on specific device driven signals, which interact with tissues in the body or carcass at the atomic or molecular level resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively.
The electromagnetic signal produced by the instrument may originate from mechanical energy like sound waves (Ultrasound – US), “photon” radiation (X-ray-Computed Tomography – CT, Dual Energy X-ray Absorptiometry – DXA), or radio frequency waves (Magnetic Resonance Imaging – MRI). The signals detected by corresponding instruments are being processed to measure for example tissue depths, areas, volumes or distributions of fat, muscle (water, protein), and partly bone or bone mineral.
Among the techniques covered in this review paper, CT is the most accurate one followed by MRI and DXA, while US can be used for all sizes of farm animal species – from pigeons to buffalo – even under field conditions. CT, MRI, and US can provide volume data, while only DXA delivers immediate whole body or carcass composition results without (2D) image manipulation. Because of the ease of use and availability, US is the most often used non-invasive technique for farm animal testing and carcass grading. CT, because of its high accuracy, is being used as a well advanced technique for modern pig and sheep breeding programs.
These breeding programs help on one side to meet the future needs of consumers in terms of nutrition and product quality and on the other side provide additional insight into skeletal stability and pelvic dimensions of farm animals, or the size of the gastrointestinal tract of ruminants like sheep or cattle.
Read the full open access paper here
Authors: A.M. Scholz, L. Bünger, J. Kongsro, U. Baulain, A.D. Mitchell