Ultrasonic sound waves of about 2 million cycles per second can pass through living tissue. Used to determine sheep pregnancy, these sound waves are painless and have no harmful after-effects to the ewe or fetus

Alexander, Maurice A.

Keisler, Duane H.

McDonald, Cynde Ann

Thompson, James O.

University of Missouri: MOspace

University of Missouri ExtensionG2610, Reviewed October 1993Sheep Pregnancy Checking By Ultrasonic SoundMaurice A. Alexander, James O. Thompson, Cynde McDonald and Duane H. KeislerDepartment of Animal SciencesUltrasonic sound waves of about 2 million cycles per second can pass through living tissue. Used to determinesheep pregnancy, these sound waves are painless and have no harmful after-effects to the ewe or fetus.The working part of the instrument is the transducer; it transmits and receives the sound waves. Thetransducer may take various shapes and may be located on various positions on the pregnancy checking unit.It may also be attached permanently to the unit or may be connected by a shielded cable. A crystal in thetransducer converts electrical energy into sound energy, which is sent into the animal. These sound waves donot travel through air; consequently, air must be sealed out with a non-detergent motor oil or otherappropriate sealant.When these sound waves encounter interfaces of different kinds of tissue — skin, fat, lean, or connective —they are reflected back to the transducer, converted to electrical energy and analyzed.If the instrument receives signals that indicate pregnancy, the instrument indicates this with a steady light orsignal, or both.Results of an MU study evaluating the pregnancy detector Scanopreg* on sheep are summarized:Number checked Number pregnant Number open Number pregnant lambed Number open lambed84 72 12 72 0*MU does not endorse or recommend any product mentioned by brand name.Based on lambing dates, the average day of gestation when pregnancy was detected by the Scanopreg wasday 57. This is comparable to the 60 day recommendation offered by Scanopreg manufacturers.As soon as the ewe becomes pregnant, the uterus begins to fill with fluid. The weight of the pregnant uteruscauses it to sink downward through the intestines to the bottom of the abdominal wall. As gestationprogresses, fluid continues to expand the uterus forward and to the animal's right side. At about 60 days, thereis enough uterine fluid to be detected by ultrasonic techniques. Beyond 120 days, the fetus fills the uterus andultrasonic methods can no longer detect pregnancy.DiagnosisTo diagnose pregnancy, the sound beam must be aimed correctly. Hold the probe flat against the non-woolyarea of the right flank, 2 to 3 inches forward to the right nipple. Aim the sound beam forward about 35degrees and toward the opposite side behind the last rib. The urinary bladder is just behind the uterus. If thesound beam is directed through it, the instrument gives an erroneous pregnant signal.G2610 Sheep Pregnancy Checking by Ultrasonic Sound | University of Mi... http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.asp...1 of 2 2/1/2010 3:42 PMFor accuracy, the ewe should be standing in a normal position. Two people speed pregnancy checking whenone catches and holds the ewes while the other makes the check.ProcedureTurn power switch on and check function of instrument.Apply non-detergent oil to the probe and touch the probe to the flank as previously indicated.Good contact is essential, so use sufficient oil to dissolve any foreign substance or flaked dried skin scales. Ifthe instrument light flickers, apply more oil for good contact.Pregnancy is indicated by a steady, uninterrupted tone or green light and, on visual-read models, by theabsence of light or peaks in the middle of the screen.In most cases, when checking bred ewes that are 60 or more days into gestation, the instrument signalspregnancy almost immediately after the probe contacts the flank.Open is indicated by red or amber lights and on visual read models, by a continuous set of dots orpeaks.Causes for diagnostic errorsIncorrect angle of beam direction: beam direction through urinary bladderGas pockets in intestinesEwes in estrus occasionally collect enough uterine fluid to cause the uterus to drop to the bottom ofabdominal cavity.G2610, reviewed October 1993Related MU Extension publicationsNCR240, Management Guideline for Efficient Sheep Productionhttp://extension.missouri.edu/publications/DisplayPub.aspx?P=NCR240NCR379, Sheep Diseaseshttp://extension.missouri.edu/publications/DisplayPub.aspx?P=NCR379Order publications online at http://extension.missouri.edu/explore/shop/ or call toll-free 800-292-0969.G2610 Sheep Pregnancy Checking by Ultrasonic Sound | University of Mi... http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.asp...2 of 2 2/1/2010 3:42 PM

Sheep pregnancy checking by ultrasonic sound (1993)

Abstract

Similar works

Full text

Available Versions

University of Missouri: MOspace