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Encyclopedia Of Animal Science - U

Từ điển khoa học động vật vần U | Ultrasound Technology Live Animal and Carcass Evaluation James R. Stouffer Cornell University Ithaca New York U.S.A. INTRODUCTION Breeders producers packers retailers and researchers are becoming more concerned about carcass traits as the livestock industry moves closer to the concept of valuebased marketing. Animal scientists have desired the ability to determine the carcass traits of composition and quality in live animals as aids in selection of breeding stock and ideal marketing time for slaughter animals to study the mechanism of growth and development and to understand the effect of nutrition. This has led to the development of noninvasive objective evaluation methods including ultrasound. Early ultrasound equipment was large and had limited performance capabilities. Subsequent developments have resulted in high-performance durable and lightweight ultrasound equipment that is associated with portable computers and sophisticated software. These systems produce rapid and accurate information for determining composition and quality characteristics of live animals and carcasses. PROPERTIES OF ULTRASOUND Ultrasound refers to high-frequency sound waves that are generated and received by a transducer associated with electronic equipment and generally a cathode ray screen. Ultrasound waves generated by the transducer are propagated through animal tissue until a slight change in density such as tissue interfaces will cause a portion of the ultrasound waves to be reflected back to the transducer. These signals appear on a screen in proportion to time and therefore can be measured in terms of distance and tissue depth. frequencies of 1 to 3 MHz were used to detect tissue interfaces as well as flaws in metal. This equipment was also used to evaluate beef and lambs. Clipping of hair at the examination site and the application of motor oil as a couplant was required because of the limited performance of the equipment available at that time. Although the fat thickness was .