Vet’s Advice
Testing for Freemartinism
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roducers have several options available to them when checking for and identifying freemartins in their herd. If twinning is high in your herd (some herds approach 10%) and with half of the sets being mixed sexes freemartins are not an uncommon phenomena. The real issue here is identifying them and making sure they don’t get kept as replacements or sold and tried to be bred as a replacement heifer. This is when losses become big, If freemartins are kept for several years trying to get bred when they are sterile and will never breed. This is a grade loss because of age and feed loss when in reality if put into the feedlot with the non-replacement heifers are they will perform exceptionally. Right at birth when mixed twins occur we know in 90-95% of the cases the heifer is a true freemartin. It is good in some cases to find out the other 5% as in the case of valuable breeding stock as you may want to retain them as a breeding animal. The choice will be up to you at that time. So a farmer could presume they are all freemartins and put them all on the culling list. Identification becomes critical for sorting the freemartins out at weaning or when replacements are selected. Keep in mind freemartins (because of the influence of the male hormones) grow extremely well so they will often be in the top 25% of the heifers for size and are often considered for replacements. I don’t know how many times over the years when palpating heifers for select replacement sales freemartins are detected. Marking their eartag with twin or a different color or tagging in the opposite ear or the same as steers are all ways to make it a visual determination of freemartins. The writing of “twin” also helps the feedlot or producer down the road. I even notch tags, which is visual and draws your attention plus making them easy to sort out later. In regards to absolutely testing, the external genitalia can be checked and a very prominent clitoris and what I call loosely attached or feathery vulval lips are a dead give away. The genital opening may be located way down between the back legs towards where the prepuce would be on a bull. For the others that have a more normal looking external genitalia there is a measuring device commercially 22
available which when inserted into the vagina measures the depth of the vaginal vault. When done on newborns up to a few days of age the measuring device has a negative (short measurement) middle (Indeterminate) and long or positive position. The short or negative position means it is NOT a normal heifer and is thereby a freemartin. I am currently doing some work with bison and the same is true with them. I even used this device on a 300 lb suspect bison freemartin heifer and this cattle device can be used on bison as well. The final test is a blood test where whole blood is drawn by your veterinarian and sent into the Saskatchewan Research Council lab in Saskatoon, Saskatchewan. With the blood test they can determine freemartins as well. Both the above methods are very accurate. Otherwise you need to wait till the heifers are much older before they can be palpated and freemartin status determined then. Very occasionally a freemartin heifer is born by-itself. The best possible explanation here is it started as a twin and the other fetus was resorbed. As long as the pregnancy has reached 60 days with both fetuses the male fetuses exerts enough hormonal influence on the heifer for it to become a freemartin. These will get missed at birth. Owners may notice when the heifers urinate as they often spray urine straight back not down in a stream like a normal heifer. Palpating heifers to be used as replacements besides removing pregnant ones will pick up the freemartins. Beware of single dairy heifers being sold, as they often are freemartins and that is the reason they are being marketed. Freemartin heifers still grow very well and the question is should they run with heifers or steers. Most often they are fed with the heifers as they still can get ridden and picked on if in a steer pen. Some have rudimentary ovarian tissue so still cycle. If you can plan ahead when implanting they do a bit better with a steer implant such as “Revalor S” if you really want to fine-tune your management. They need to be marketed though as they are totally sterile and will never breed. Identify any freemartins this spring and feed them out you won’t be disappointed.