Agrotecnio Centre, Lleida, Spain.
Animal Science, University of Lleida, Lleida, Spain.
Reprod Domest Anim. 2022 Dec;57(12):1649-1651. doi: 10.1111/rda.14258. Epub 2022 Sep 17.
The condition of freemartinism occurs in the bovine heterosexual twin foetuses and refers to the resulting infertile female. Vascular anastomoses of the foetal membranes are the major reason of this anomaly. This study examines whether single born heifers following induced twin reduction at 28-34 days of pregnancy could develop normal reproductive functions. The study population derived from 367 lactating dairy cows carrying: unilateral twins (n = 178), bilateral twins (n = 174) or triplets (n = 15), in which manual embryo reduction was performed. The final study population was constituted of 95 single born twin females that reached 12 months of life and entered into the AI period. Of these heifers, 40 have had one unilateral co-twin, 49 one bilateral co-twin, and 6 two contralateral co-twins. A total of 1688 heifers inseminated during the same period were used as controls to compare the rates of pregnancy at 15 months of age, culling due to infertility and birth before the age of 24 months. No differences were detected between groups. With an accepted incidence rate of 50% heterosexuality for all twin sets, we should assume that half of our study population had a male co-twin. Our results indicate lack of effect of the male co-twin on normal development of the gonads and genital tract of his female partner during the late embryonic period.
双胎中雄性去势现象发生于牛的异性双胞胎胎儿中，指的是由此产生的不育雌性。胎膜的血管吻合是这种异常的主要原因。本研究旨在探讨在妊娠 28-34 天时通过人工诱导减少双胎数量后，单胎出生的小母牛是否能发育出正常的生殖功能。研究人群来自于 367 头哺乳期奶牛，其中携带：单侧双胞胎（n=178）、双侧双胞胎（n=174）或三胞胎（n=15），对其进行了手动胚胎减少。最终的研究人群由 95 头达到 12 月龄并进入人工授精期的单胎双胎雌性组成。这些小母牛中，40 头有单侧同胎，49 头有双侧同胎，6 头有双侧异胎。同期接受人工授精的 1688 头小母牛被用作对照组，以比较其 15 月龄时的妊娠率、因不育而淘汰率和 24 月龄前的产犊率。组间无差异。根据所有双胞胎的异性发生率为 50%，我们假设我们的研究人群中有一半的小母牛有一个雄性同胎。我们的结果表明，在胚胎后期，雄性同胎对其雌性伴侣的性腺和生殖道的正常发育没有影响。
