Kelly has a Holstein heifer that he bought at a sale two years back, she was one of a twin the other being a bull calf he was told. when she began to come in heat I told him there was not much chance she would breed but he kept her against my advice and Wednesday morning she delivered a healthy bull calf. Kelly has a milk cow!
I don't know if they were mistaken about her being a twin because there is not much of a chance that a heifer will breed if she is twin to a male calf or pehaps she was that one in a 10% out of 100 that did breed.
By Laurie Ann Lyon, Cow Calf Corner, Oklahoma Coopereative Extension Service. Freemartinism is recognized as one of the most severe forms of sexual abnormality among cattle.
This condition causes infertility in the female cattle born twin to a male. When a heifer twin shares the uterus with a bull fetus, they also share the placental membranes connecting the fetuses with the dam.
A joining of the placental membranes occurs at about the fortieth day of pregnancy, and thereafter, the fluids of the two fetuses are mixed. This causes exchange of blood and antigens carrying characteristics that are unique to each heifers and bulls. When these antigens mix, they affect each other in a way that causes each to develop with some characteristics of the other sex. Although the male twin in this case is only affected by reduced fertility, in over ninety percent of the cases, the female twin is completely infertile. Because of a transfer of hormones or a transfer of cells, the heifer's reproductive tract is severely underdeveloped and sometimes even contains some elements of a bull's reproductive tract. A freemartin is genetically female, but has many characteristics of a male.