What is a freemartin?

What is a freemartin?

• A. Process by which ova are produced by the female.
• B. Sterile female calf born twin to a male calf.
• C. Respiratory viral disease that causes infertility.
• D. Testicles remain in the body cavity.

Answer: (B)

The main idea here is that a freemartin is a sterile female calf born twin to a male. In heterosexual twin pregnancies in cattle, the twins share placental blood vessels, so hormones produced by the male twin—especially testosterone and anti-Müllerian hormone—circulate to the female fetus. This hormonal exposure masculinizes parts of the female reproductive tract and disrupts normal development of the Müllerian structures (uterine horns, ovaries), often resulting in infertility or severely reduced fertility. The female calf is typically unable to cycle normally or conceive due to these developmental changes, which is why she is described as a freemartin. This isn’t about ova production in the normal sense, a respiratory viral disease, or retained testicles. Those scenarios describe different conditions, whereas freemartin specifically refers to the sterile female twin arising from hormonal influence during prenatal development.

The main idea here is that a freemartin is a sterile female calf born twin to a male. In heterosexual twin pregnancies in cattle, the twins share placental blood vessels, so hormones produced by the male twin—especially testosterone and anti-Müllerian hormone—circulate to the female fetus. This hormonal exposure masculinizes parts of the female reproductive tract and disrupts normal development of the Müllerian structures (uterine horns, ovaries), often resulting in infertility or severely reduced fertility. The female calf is typically unable to cycle normally or conceive due to these developmental changes, which is why she is described as a freemartin.

This isn’t about ova production in the normal sense, a respiratory viral disease, or retained testicles. Those scenarios describe different conditions, whereas freemartin specifically refers to the sterile female twin arising from hormonal influence during prenatal development.