By Obioha Durunna, Regional Livestock Specialist, Prince Albert
Twin-bearing cows can have an overall positive effect on cattle operations if managed properly, but freemartinism in female co-twins can pose some challenges. Understanding this sexual abnormality and how to identify affected animals early can help producers manage their breeding plans without increasing their cost of production.
What is freemartinism?
Freemartinism is an abnormal sexual development of a female fetus that has a male twin. The condition is associated with fraternal twins of different sexes. Some studies have reported that up to 95 per cent of female co-twins could be freemartins. It can occur in single births, but the incidence is low.
A freemartin originates as a female but then acquires male attributes from the male co-twin.
The placentas of the male and female fetuses may fuse, allowing the exchange of fetal cells and hormones. This means that the calf will have both male and female genotypes.
Because the sexual development of the male fetus occurs first, male hormones masculinize the female twin rendering it infertile.
The female may not be affected if the male twin is aborted before the onset of sexual development of the fetus, if the placentas do not fuse at all or if they fuse after the sexual development of both fetuses.
The male co-twin is affected to a lesser extent.
Often there are not any negative effects on bulls, but it can have an impact on testicular size, semen quality and over-all reproductive abilities.
Tools are available to identify freemartins.
Freemartins can be identified using diagnostic methods such as clinical examinations, DNA analysis or hormone tests.
Clinical examinations can reveal shorter vaginal lengths which end blindly and do not interact with the uterus. Other signs include the presence of long, coarse vulval hair, an enlarged clitoris or the absence of a cervix.
Laboratory diagnosis through genetic testing can expose chromosomal abnormalities. Blood typing may indicate the presence of two different blood groups, while some DNA tests may reveal male specific fragments or genetic markers.
Some of these tests can be done soon after birth saving the producer costs associated with heifer development. Further, pregnancy testing and early diagnosis of female co-twins will go a long way to helping producers make useful management decisions.
Freemartins can reduce cost of cattle production.
The sterility of freemartins cannot be reversed or treated. Although freemartins do not have a reproductive value to your operation, they can be raised for beef and substantially reduce production costs as a result of extra pounds of meat at weaning.
For more information please contact your Regional Livestock Specialist or the Agriculture Knowledge Center at 1-866-457-2377.