In vitro embryo production (IVEP) is an important advanced reproductive technology and has great potential in enhancing livestock production. However, in vitro culture (IVC) of embryos exposes them to stress resulting in compromising quality and efficiency of embryo production. Melatonin has been reported in several studies to reduce oxidative stress and improve the efficiency of IVEP. Our objective was to evaluate the effect of melatonin supplementation in IVC media on cleavage rates of bovine embryos. Bovine ovaries (n = 22) were obtained from local abattoir with ovarian weight of 7.29 ± 3.31 g, and size of 3.65 ± 0.69 cm. Cumulus-oocyte complexes (COCs) were recovered from 2 to 8 mm size follicles by aspiration using an 18-gauge needle attached with a 10 mL syringe. COCs were matured, fertilized, and cultured in vitro using IVF Bioscience bovine media and their protocols. Oocytes were in vitro matured for 23 h at 38.8°C, 5.5% CO2 in a humidified atmosphere and assessed for maturation by assessing COC expansion. Fully expanded and partially expanded COCs were fertilized for 20 h in a 4-well dish with frozen/thawed bull semen. Following IVF, the cumulus cells were removed by vertexing, and the presumptive zygotes were cultured in vitro with and without 1 µM melatonin in 4-well dishes in triplicates under the oil for embryo development at 38.8°C and 5.5% CO2. Cleavage rates were determined on d 3 of culture. The percentage of cleaved embryos was calculated as (number of zygotes cleaved/total number of fertilized oocytes) x100. Data were analyzed by student’s unpaired t- test with Welch’s correction using GraphPad Prism software. The cleavage rate was greater in melatonin supplemented group (54.17 ± 11.24%) than the control (49.83 ± 7.36%) but the difference was not significant (P > 0.05). In conclusion, under our experimental conditions, melatonin supplementation during embryo culture, following IVM/IVF of the bovine oocytes, did not significantly improve cleavage rates.

中文翻译：

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PSXIII-14 体外胚胎培养期间补充褪黑激素对牛卵母细胞体外成熟和受精后卵裂率的影响


体外胚胎生产 （IVEP） 是一项重要的先进生殖技术，在提高畜牧生产方面具有巨大潜力。然而，胚胎的体外培养 （IVC） 使它们暴露在压力下，导致胚胎生产的质量和效率受到影响。多项研究报道，褪黑激素可以减少氧化应激并提高 IVEP 的效率。我们的目的是评估在 IVC 培养基中添加褪黑激素对牛胚胎卵裂率的影响。牛卵巢 （n = 22） 来自当地屠宰场，卵巢重量为 7.29 ± 3.31 g，大小为 3.65 ± 0.69 cm。使用附有 10 mL 注射器的 18 号针头抽吸，从 2 至 8 mm 大小的卵泡中回收卵丘-卵母细胞复合物 （COC）。使用 IVF Bioscience 牛培养基及其方案在体外成熟、受精和培养 COC。卵母细胞在 38.8°C、5.5% CO2 的潮湿气氛中体外成熟 23 小时，并通过评估 COC 扩增来评估成熟度。将完全扩增和部分扩增的 COCs 在含有冷冻/解冻的公牛精液的 4 孔培养皿中受精 20 小时。IVF 后，通过顶点去除卵丘细胞，并在 38.8°C 和 5.5% CO2 的油下，在 4 孔培养皿中一式三份培养有和不含有 1 μM 褪黑激素的推定受精卵。在培养的第 3 天测定切割率。切割胚胎的百分比计算为 （切割的受精卵数/受精卵母细胞总数） x100。使用 GraphPad Prism 软件通过学生未配对的 t 检验和 Welch 校正分析数据。补充褪黑激素组 （54.17 ± 11.24%） 的切割率高于对照组 （49.83 ± 7。36%），但差异不显著 （P > 0.05）。总之，在我们的实验条件下，在牛卵母细胞 IVM/IVF 之后，胚胎培养期间补充褪黑激素并没有显着提高卵裂率。