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Breeding / Calving Issues
? bout free martin?
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<blockquote data-quote="Fire Sweep Ranch" data-source="post: 1224405" data-attributes="member: 18809"><p>Here is a definition that, I think, is easier to follow that Inyeti's description: "When a cow is pregnant with two fetuses, the extraembryonic membranes of each fetus frequently fuse forming a common chorion[1]. Thus, both the male and female fetus share the same cotyledons. Cotyledons, which are distributed across the surface of the chorion, consist of many blood vessels and connective tissue. By sharing the same cotyledons, both the male and female fetus share the same blood supply. This blood provides both the male and female twins with the same hormonal combination (including testosterone and anti-müllerian hormone). The fusion of the membranes generally occurs within 1 month of gestation, right before sexual differentiation of the fetus takes place. Since the sexual differentiation of the testes occurs before the ovaries (recognizable at around 40 days), the hormones produced by the testes work to inhibit the reproductive growth in the female fetus. The hormone that has this negative effect is anti-müllerian hormone[2] which stops the growth of the paramesonephric ducts[3] in the female fetus. Thus, the female heifer, now known as a freemartin, has an incomplete development of the reproductive tract. This includes the ovaries which are underdeveloped and are incapable of producing hormones such as estrogen, greatly reducing the femininity of this heifer." The [3] goes on to develop into the ovaries, Fallopian tubes, and uterus. </p><p>I argue that it is Environmental, because it happens due to the environment; if the male twin was not there, she would have formed normally. If it was genetic, it would come as a result of genetic flaw, regardless of a male twin or not. The gonad is a entirely different story!</p><p>She can blame it on her brother! </p><p>That still does not explain why some male/female twins are fertile. I do not want your speculation on God, and in science, "shyt" does not "happen", as you said! There is a scientific explanation...</p></blockquote><p></p>
[QUOTE="Fire Sweep Ranch, post: 1224405, member: 18809"] Here is a definition that, I think, is easier to follow that Inyeti's description: "When a cow is pregnant with two fetuses, the extraembryonic membranes of each fetus frequently fuse forming a common chorion[1]. Thus, both the male and female fetus share the same cotyledons. Cotyledons, which are distributed across the surface of the chorion, consist of many blood vessels and connective tissue. By sharing the same cotyledons, both the male and female fetus share the same blood supply. This blood provides both the male and female twins with the same hormonal combination (including testosterone and anti-müllerian hormone). The fusion of the membranes generally occurs within 1 month of gestation, right before sexual differentiation of the fetus takes place. Since the sexual differentiation of the testes occurs before the ovaries (recognizable at around 40 days), the hormones produced by the testes work to inhibit the reproductive growth in the female fetus. The hormone that has this negative effect is anti-müllerian hormone[2] which stops the growth of the paramesonephric ducts[3] in the female fetus. Thus, the female heifer, now known as a freemartin, has an incomplete development of the reproductive tract. This includes the ovaries which are underdeveloped and are incapable of producing hormones such as estrogen, greatly reducing the femininity of this heifer." The [3] goes on to develop into the ovaries, Fallopian tubes, and uterus. I argue that it is Environmental, because it happens due to the environment; if the male twin was not there, she would have formed normally. If it was genetic, it would come as a result of genetic flaw, regardless of a male twin or not. The gonad is a entirely different story! She can blame it on her brother! That still does not explain why some male/female twins are fertile. I do not want your speculation on God, and in science, "shyt" does not "happen", as you said! There is a scientific explanation... [/QUOTE]
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