López-Gatius Fernando, Garcia-Ispierto Irina
Agrotecnio Centre, 25198 Lleida, Spain.
Transfer in Bovine Reproduction SLu, 22300 Barbastro, Spain.
Animals (Basel). 2023 Apr 12;13(8):1326. doi: 10.3390/ani13081326.
This study provides new unique information on bovine twin pairs during the late embryonic period (28-34 days of pregnancy) in relation to (1) a predictive ultrasound measurement that was differential for sexing heterosexual twins; (2) intrauterine embryonic growth patterns in twin pairs; and (3) a higher vulnerability of female embryos compared to males following an induced embryo reduction in heterosexual twins. The study population comprised 92 dairy cows carrying bilateral twins. A length difference between co-twins equal to or greater than 25% in around 50% of pregnancies served to determine the sex of embryos with 100% accuracy in heterosexual twins, which was assessed four weeks later on the remaining fetus after twin reduction. The apparent rates of growth of twin pairs and of individual male and female embryos from day 28 to 34 of gestation were similar to established growth pattern standards for singletons. Mean embryo sizes in relation to gestational age were smaller by some 5 days' growth equivalent in twins compared to singletons. After the reduction in the female embryo in heterosexual twins, the risk of male embryo loss was null. This new information allowed for sex selection at the time of twin reduction.
本研究提供了关于妊娠后期（妊娠28 - 34天）牛双胞胎的全新独特信息，涉及以下方面：（1）一种用于区分异性双胞胎性别的预测性超声测量方法；（2）双胞胎对中子宫内胚胎的生长模式；（3）在异性双胞胎中进行人工胚胎减灭后，雌性胚胎相较于雄性胚胎具有更高的脆弱性。研究群体包括92头怀有双侧双胞胎的奶牛。在约50%的妊娠中，双胞胎之间的长度差异等于或大于25%，可用于以100%的准确率确定异性双胞胎胚胎的性别，在减胎四周后对剩余胎儿进行评估。从妊娠第28天到第34天，双胞胎对以及单个雄性和雌性胚胎的表观生长速率与已确立的单胎生长模式标准相似。与单胎相比，双胞胎中与胎龄相关的平均胚胎大小约小5天的生长当量。在异性双胞胎中减灭雌性胚胎后，雄性胚胎丢失的风险为零。这些新信息使得在减胎时能够进行性别选择。
