Viana Joao Henrique Moreira, Silva Bianca Damiani Marques, de Moura Rodrigo Martins, Féres Luiz Fernando Rodrigues, Figueiredo Ricardo Alamino
Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF, Brasil.
Universidade de Brasília, Brasília, DF, Brasil.
Anim Reprod. 2024 Aug 16;21(3):e20240069. doi: 10.1590/1984-3143-AR2024-0069. eCollection 2024.
With the development of technologies, embryos can be produced using oocytes retrieved directly from the ovaries, i.e., regardless of ovulation. This has allowed the use of different animal categories as oocyte donors, including prepubertal cattle. The advantages of using this strategy to shorten the generation interval and accelerate genetic gain over time were soon recognized, and the first offspring generated using oocytes collected from calves were born in the early 1990s. Nevertheless, embryo production from calves and prepubertal heifers remains a challenge. The oocytes collected before puberty present low developmental potential, and the subsequent blastocyst rates are consistently lower than those from pubertal females. The acquisition of developmental competence by the oocytes occurs progressively throughout the prepubertal period, which can be subdivided into an early, intermediate, and late prepubertal (or peripubertal) phases, each characterized by different physiological and endocrine features. Therefore, embryo yield increases with age but will only achieve its maximum after puberty. The most common strategy to improve oocyte developmental potential before puberty is the use of gonadotrophic stimulation prior to oocyte retrieval. The results with superstimulation, however, vary among studies, depending on the source, dose, and length of FSH treatment, as well as the age and breed of the donors. The use of calves and prepubertal heifers as oocyte donors should also consider the possible impacts of the oocyte retrieval technique (LOPU or OPU) and the use of exogenous hormones on their subsequent fertility and productive life.
随着技术的发展，可以使用直接从卵巢获取的卵母细胞来生产胚胎，即无论是否排卵。这使得包括青春期前的牛在内的不同动物类别都可以作为卵母细胞供体。人们很快认识到采用这种策略来缩短世代间隔并随着时间的推移加速遗传进展的优势，并且利用从犊牛收集的卵母细胞培育出的首批后代于20世纪90年代初诞生。然而，从犊牛和青春期前的小母牛生产胚胎仍然是一项挑战。青春期前收集的卵母细胞发育潜力较低，随后的囊胚率始终低于青春期雌性的囊胚率。卵母细胞发育能力的获得在整个青春期前阶段逐步发生，该阶段可细分为青春期前早期、中期和晚期（或青春期前后）阶段，每个阶段具有不同的生理和内分泌特征。因此，胚胎产量随年龄增加而增加，但只有在青春期后才会达到最大值。提高青春期前卵母细胞发育潜力最常用的策略是在采集卵母细胞之前使用促性腺激素刺激。然而，超刺激的结果在不同研究中有所不同，这取决于促卵泡素治疗的来源、剂量和时长，以及供体的年龄和品种。将犊牛和青春期前的小母牛用作卵母细胞供体时，还应考虑卵母细胞采集技术（腹腔镜卵巢穿刺或经阴道超声引导下卵巢穿刺）以及外源激素的使用对其后续生育能力和生产寿命的可能影响。
