Get the Most out of Ultrasound Pregnancy Exams
contributed article by Dr. Vince Collison, Collison Embryo and Veterinary Services,
Rockwell City, Iowa
This is the time of year where producers are starting to work calves, but usually will wait until November through December to pregnancy check and work cows. We get more requests to do pregnancy exams every year with an ultrasound. Here are a few tips to get the most out of using ultrasound for pregnancy diagnosis.
Fetal Aging
One of the best benefits of ultrasound is that you can have the fetus aged. When selling bred heifers, fetal aging is a procedure that will add a lot of value. Most ultrasound units have a fetal aging table incorporated into the programming that allows the fetus to be measured for its days of age. This is best done in the first 120 days of pregnancy. At this point the fetus is small enough to fit on the screen for measurement.
In the first 120 days, we use the body diameter and find this is fairly accurate. There can be some variation as the fetus gets older. We have found that as the fetus grows it can occasionally measure up to 10 days later on known AI dates. Also, after 120 days we have to rely more on eye socket measurements due to the fetus dropping out of range of the viewing screen. We have found that the eye socket measurements on these older fetuses are not quite as precise as the trunk diameter on younger fetuses.
Ascertaining Sex of Fetus
One of the other benefits is that the sex of the fetus can be determined. This is best done between 60 and 90 days of pregnancy. If we try to sex fetuses after 90 days, it can be done, but many pregnancies drop down far enough that the fetus cannot be positioned to visualize the sex. After 120 days it is usually impossible to visualize the sex. If fetal sexing is important, make sure it is done in this 60-to-90-day range.
Determining Fetus Viability
The viability of the fetus can be determined. Early embryonic loss occurs occasionally in the first 60 days of pregnancy and ultrasound can determine the viability of the fetus via the heartbeat. If the fetus is not viable, a prostaglandin can be given to help the cow expel the fetus and prevent complications. Also, we have found severe birth defects on ultrasound such as two-headed calves and calves with Schistostomas reflexus.
Identifying Twins
Twins can be diagnosed. If there are twins, they can often be identified.
Management Benefits
All these things can be helpful for managing the calving season. Many producers will put tags in the ears that are color coded according to a range of calving dates. Also, when selling bred heifers or cows it is a great marketing tool to have confirmed AI dates and subsequent calving dates if bred to the bull.
To get the most from ultrasound, many producers will need to move the pregnancy exam time frame up earlier. If producers wait until the normal November/December time range, most of the pregnancies will be too far along to measure the fetuses or identify the sex. Most of the ultrasound pregnancy checking we do is in the late July through October time frame.
Also, at this time we often are pouring the cows with something for fly and parasite control. We recommend using something that has zero withholding at this time. This makes it a lot easier so that all cows can be treated and culling decisions can be made at a later time. Also, cows destined for the sale barn as culls can accidentally get poured and this eliminates any withholding issues.
As a final note, pregnancies need to be a minimum of 28 to 30 days along to identify with ultrasound. If bulls are still running with the cows at the time of pregnancy exam, then any identified as not pregnant will need to be rechecked after being pulled from the bulls for 30 days.
learn more www.collisonembryoservices.com
Dr. Vince Collison is co-owner of Collison Embryo and Veterinary Services PAC
in Rockwell City, Iowa.
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