Application of ReproScan ultrasound equipment in the reproductive management of sheep and goats.

Recommended Equipment

1. C60 3.5 MHz T handled probe units ReproScan ultrasound equipment with C60 probes are ideal for sheep and goats. The C60 probe gives a depth of scan over 20 cm which is necessary for view the fetus and uterus. The T handle is comfortable to hold and allows the person to press the probe deep into the inguinal area for better contact and targeted scanning.

2. 4.0 MHz convex rectal probe units. ReproScan ultrasound equipment with 4.0 convex rectal probes can be used effectively for sheep and goats. The 4.0 MHz probe gives a depth of scan over 20 cm. The probe is gripped with one’s thumb and index finger and pressed deep into the inguinal area. This probe can be used transrectally as well. Settings on the 3 units shown below can be adjusted to give good images while scanning sheep and goats.

Transabdominal scanning

Transabdominal scanning of sheep and goats allows for a very efficient and accurate means of detecting pregnancy. The speed of scanning for experienced practitioners is largely a function of the efficiency of the animal handling system at a given farm. Speed and efficiency are also gained by use of an efficient means of applying lubricant (ultrasound gel) to the probe to allow for air-free skin contact, facilitating sound wave transmission. The ideal window of pregnancy for transabdominal scanning is day 40-70. Producers are advised to limit ram/buck exposure to no more than 2 estrus cycles (34 days in sheep and 42 days in goats) if a single scanning session is desired. Ideally, one would schedule scanning for 40 days following ram/buck removal. Pregnancy can also be detected with higher frequency probes (5-10 mHz) such as the BoviScan Linear or BoviScan HD. The linear rectal probe is inserted in the rectum with a Linear ReproArm. This allows placement of the probe closer to the gravid uterus, allowing visualization of pregnancy as early as day 18, with a conceptus size of less than 0.8 cm. The need for detection this early would likely be only in special cases when very early detection is desired and is not a general need.

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Determination of Stage of Pregnancy

Stage of pregnancy can be quantified with some degree of accuracy with transabdominal scanning. Experienced practitioners are able to look at the relative proportions of placentome size (component of the sheep/goat placenta) to fluid space volume to fetal size along with changes in density of fetal bones to predict stage of pregnancy with some degree of accuracy. It is also possible to take measurements early in pregnancy of the size of the embryo or, later, of various anatomical features of the fetus (head diameter and crown to rump length and apply these measures to a chart to predict fetal age. Researchers have found that each of these fetal measurements has an optimal range for use, with these ranges overlapping as follows: embryonic vesicle day 28-40, crown to rump length day 40-70, head diameter day 40-100. As pregnancy progresses beyond day 70, it becomes harder to take these measurements, however, as the distance to fetus may be too great due to fetal positioning within the uterus.

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Determination of Fetal Number

Fetal number can be quantified with reasonable accuracy in the day 40-70 stage of pregnancy as well. Skilled practitioners have error rates less than 5% in prediction of fetal number, although accuracy is hard to quantify from birth records due the natural occurrence of fetal death and reabsorption following the time of scanning in mid-pregnancy to term. Prediction of fetal number in higher order multiples (triplet or greater pregnancies) also has a higher degree of error compared to single or twin pregnancies. Accurate quantification of fetal number also takes more time than simple yes/no pregnancy detection, slowing animals scanned per hour to When counting fetuses using a C60 3.5 MHz probe or 4.0 MHz convex rectal probe, both sides of the ewe or doe should be scanned to increase accuracy. This may involve going behind the ewes or tipping the ewes on end.

Ultrasound Gel

Ultrasound sound waves must travel through a liquid medium. There are a few methods of delivering gel to the face of the probe.

1. Apply commercial Ultrasound Gel to the face of the probe prior to each examination.

2. Mix J Lube in a 5 gallon bucket. Dip probe into the bucket prior to each examination. Use lots of J Lube.

3. Make a tubular system that applies a liquid to the face of the probe and/or inguinal area of the ewe/doe. (This is done in some parts of the world that scan large numbers of sheep. Not commercially available.)

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Setting Your ReproScan Ultrasound Unit for Sheep and Goats

It is important to change the settings on your Flexx, BoviScan S60, BoviScan Curve and XTC to the appropriate settings to optimize the image when scanning sheep and goats. Factors that affect image quality include fat, skin thickness, dirt on skin, amount of ultrasound gel or other liquid agent and the amount of pressure used by the person scanning. Goats will tend to have much clearer images than sheep as their skin is thinner and they have less fat in the inguinal area. Ambient light is often an issue. The ReproScan 2.0 Monitor with Sunshade works with all the ReproScan units and this monitor will solve sunlight related issues. One could consider OJO or Vista Goggles depending on setups.
Below are the main settings parameters that can be changed to make a better image for sheep and goats on your ultrasound:
Gain - Increasing the Gain → increases brightness and lowers resolution; Near refers to Near Field = top of the image and Far refers to Far Field = bottom part of the image. Use bright Gain settings for sheep and goats
Dynamic Range (Dyn) - changes the contrast of the image
Frequency (Freq.) - use a lower freq. for depth, higher freq. for near field exam. Use 2.5 setting for sheep.
Image Processing (IP) - use the highest IP setting possible eg. IP 3 gives a better image than IP 2, but dimmer. You may need to use IP 1 for sheep.
Focus - use Focus 12 on BoviScan and XTC, use F:090 or greater on Flexx
Depth - use the 22 cm depth on BoviScan and XTC, use 208 depth on Flexx

Saving Settings

Once you find settings that works for your particular type of sheep or goats, you may save the settings on your ReproScan ultrasound. Refer to your manual for instructions on how to save settings.


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Determination of Open / Empty Uterus in Sheep and Goats

Due to several factors, the non gravid (open/empty) uterus is not often visualized when using 3.5 MHz transabdominal ultrasound techniques. The view of the non gravid uterus may be obscured by skin thickness, dirt on skin, fat and intestines. The diagnosis of “not pregnant” is therefore made by doing a complete examination of the inguinal area and posterior abdomen and coming to the conclusion that there is no pregnancy.
There are techniques that have been discussed in the literature and in personal communications with other veterinarians, where transrectal scanning of the uterus is done with higher frequency probes such as using an extension arm on a 6.5 MHz linear rectal probe. With these techniques, it is reported that the non gravid uterus can be confirmed at earlier stages.

Use of ultrasound scanning information in small ruminant production

(from Application of ultrasound technology in the reproductive management of small ruminants, Richard Ehrhardt, Almudena Veiga-Lopez and Barbara Makela, Department of Animal Science, Michigan State University)

Better allocation of feed resources. Separation of ewes or does according to pregnancy status allows removal of nonpregnant animals, which then can either be culled or fed less due to their lower requirements. In some production systems, failure to remove the non-pregnant animals from the pregnant group will result in obesity. Not only is this a waste of feed resources, but a hidden cost in this may be the failure of these animals to breed when re-exposed or to be at greater risk of ketosis if they do conceive. In more prolific flocks/herds, grouping according to fetal number results in a better allocation of feed resources, particularly during late pregnancy when the nutrient demands will vary most markedly and to the greatest extent according to litter size. Those carrying singles can be fed less, with more and higher quality feed resources reallocated to those rearing multiples. This will result in a better pregnancy outcome for the entire flock/herd. The utility of fetal counting is greatest in more prolific flocks/herds as compared to those with a lambing/kidding rate of <120%.


Precision feeding to meet animal requirements during pregnancy. In more intensified production systems that utilize precision feeding management, animals can be fed precisely according to stage of pregnancy and litter size. Grouping animals using this information and feeding accordingly will reduce the incidence of metabolic disease and optimize maternal and fetal nutrition.


Optimizing birth management. Grouping according to fetal number and stage of pregnancy in both intensified and extensive production systems provides an opportunity to increase labor efficiency during the birth period. By separating ewes/does with potentially greater needs for labor at birth (those with multiples are more prone to dystocia and mis-mothering issues) from those with less (those carrying singles), one can allocate resources (labor, favorable birth paddocks with windbreaks, warmer housing facilities) appropriately to achieve the best birth outcomes.


Decision as to when to dry-off lactating animals in parlor milk production. The decision to dry-off lactating animals in parlor milk production can be made with knowledge of pregnancy status and stage. This allows animals to be managed in such a way as to allow optimal dry period length for better lactational performance and herd/flock health.


Detection of pregnancy in primiparous animals. Early detection of pregnancy allows sale of non-pregnant animals when they are still at a high market value (under 12 months of age). The ability to breed before one year of age can be used as a selection tool for increased lifetime productivity, as it has been demonstrated that ewes that lamb at 1215 months of age have a higher lifetime productivity than those that do not.

Summary

Ultrasound technology can be applied as a tool to improve reproductive management of small ruminants in a diverse array of production scenarios, from extensive production systems emphasizing wool production to intensive production systems utilizing prolific genetics with an emphasize on meat production, to small ruminant dairies. Ultrasound scanning proves to be a low-cost, accurate method of determining pregnancy status, stage of pregnancy and litter size. By grouping animals according to pregnancy status, stage and/or litter size, managers can increase production efficiency, improve allocation of farm resources and improve the health and welfare of the flock/herd.

References:

Theriogenology. 2016 Mar 15;85(5):939-945.e1. doi: 10.1016/j.theriogenology.2015.11.002. Epub 2015 Nov 11.

Transabdominal ultrasound for detection of pregnancy, fetal and placental landmarks, and fetal age before Day 45 of gestation in the sheep. Jones AK1, Gately RE2, McFadden KK1, Zinn SA1, Govoni KE1, Reed SA3.

Application of ultrasound technology in the reproductive management of small ruminants,

Richard Ehrhardt, Almudena VeigaLopez and Barbara Makela, Department of Animal Science, Michigan State University)

Prediction of Gestational Age by Transabdominal Real-Time Ultrasonographic Measurements in Saanen Goats (Capra hircus)

R.M. Abdelghafar, B.H 1 2 . Ahmed, 3M.T. Ibrahim and 4P. Mantis 1College of Veterinary Medicine, Sudan University of Science and Technology (SUST). 2Institute of Radiotherapy and Nuclear Medicine, National Ribat University (NRU). 3College of Science and Technology of Animal Production, Sudan University of Science and Technology (SUST) 4The Royal Veterinary College, University of London

Estimation of foetal age using ultrasonic measurements of different foetal parameters in red Sokoto goats (Capra hircus)

Innocent C. Nwaogu1*, Kenneth O. Anya2, and Precious C. Agada1 1Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria 2Department of Veterinary Obstetrics and Reproductive Diseases, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Nigeria

MEASUREMENTS OF FOETAL GROWTH VIA TRANSABDOMINAL ULTRASONOGRAPHY DURING FIRST HALF OF PREGNANCY AT EWES FROM SYNTHETIC POPULATION BULGARIAN MILK

N. Metodiev¹*, D. Dimov², I. Ralchev² and E. Raicheva¹ ¹ Institute of Animal Science, Department Sheep Breeding, BG - 2230 Kostinbrod, Bulgaria ² University of Forestry, Faculty of Veterinary Medicine, BG - 1756 Sofia, Bulgaria

Theriogenology. 1997 Aug;48(3):449-60. Determination of gestational age in sheep and goats using transrectal ultrasonographic measurement of placentomes.

Doizé F1, Vaillancourt D, Carabin H, Bélanger D.

Evaluation of Ultrasonography to Measure Fetal Size and Heart Rate as Predictors of Fetal Age in Hair Sheep

R.W. Godfrey1,2, L. Larson2, A.J. Weis2 and S.T. Willard3 1 Corresponding author: Email: rgodfre@uvi.edu 2 Agricultural Experiment Station, University of the Virgin Islands, St Croix, VI; 3 Department of Biochemistry and Molecular Biology,