Ultrasonic equipment for the measurement of backfat on unshorn live sheep

Because of the ease of application to the animal's exposed skin, the measurement by A-scan ultrasonics of backfat on pigs is an established technique; but difficulties are experienced with unshorn sheep because the fleece presents an obstacle, as a parting of the wool offers only a limited aperture for insonification of the subcutaneous tissues. Also, movement of the typical nervous sheep usually provides somewhat intermittent return echo signals, rendering difficult an otherwise simple measurement. The present instrument has overcome these problems by an accumulator-averaging technique, implemented by a microprocessor, allowing estimation of live backfat thickness to the nearest 0.5 mm. This paper describes the instrument function, and presents results of a series of experiments which examined the correlation with the carcass backfat thickness.