Swine pregnancy checking by ultrasonic sound (1990)

Abstract

Ultrasonic sound waves of 2 or 2.5 megahertz can pass through living tissue. These sound waves are painless to the animals and have no harmful aftereffects to a fetus. Ultrasonic sound waves will not travel through air; consequently, air must be sealed out by using an appropriate sealant such as a non-detergent motor oil, Ky jelly, or other. The transducer, which transmits and receives sound waves, is the essential part of the pregnancy detection instrument. It takes various shapes and positions on the rest of the unit. It may be attached permanently to the unit, or it may be attached by a shielded cable. The crystal in the transducer transmits and converts electrical energy into sound energy and passes it into the animal. When these sound waves encounter interfaces of tissues of different densities, such as skin, fat, lean, and connective tissue, sound waves bounce back to the transducer and convert back to electrical energy, which the instrument analyzes. The returning signals can show whether an animal is pregnant. If the signals present are the ones the instrument is programmed to read as pregnant, the instrument shows this with a steady signal.