Evolution and use of ultrasonic technology in the swine industry

The use of ultrasound to measure biological tissue dates back to at least 1950, and early ultrasonic work focused primarily on applications to human medicine. The application in livestock species was somewhat slow due to the cumbersome, fragile machines and high investment costs. Historically, the application of ultrasound to swine has focused on composition and reproductive status assessment, with most of the research carried out through land-grant institutions. Early researchers evaluated the relationship among ultrasound measurements and carcass measures. However, the accuracy of the early amplitude-depth (A-mode), single-crystal devices was often quite variable. The introduction of B-mode (brightness modality) ultrasound, using multiple-crystal transducers and displayed in real-time, greatly enhanced the accuracy of live animal composition and provided an understanding of extraneous effects on accuracy of measurements. In 1993, the U.S. swine industry implemented a national ultrasound training and certification program for composition assessment. Application of ultrasound principles has expanded to include on-line carcass composition estimation in packing facilities as well as on-farm applications for the measurement of lean growth rate and subsequent nutrition modeling. Early research in the reproduction area used Doppler ultrasound systems that measured fluid flow within the uterus. A-mode systems were evaluated in the mid 1970s. Doppler and A-mode devices, while relatively inexpensive and accurate within specified time frames during gestation, are less accurate than real-time ultrasound. Research indicates real-time ultrasound is an accurate system of pregnancy detection as early as 22 d after first mating. Enhanced technology, increased portability, and reduced cost have allowed ultrasound to be a common tool used in swine units, packing plants, and research institutes. Future research in the areas of composition, muscle quality, and reproductive biology, along with enhanced imaging capabilities, will lead the way to new, innovative applications.