Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, 0454, Oslo, Norway.
SpermVital AS, Holsetgata 22, 2317, Hamar, Norway.
Acta Vet Scand. 2020 Mar 12;62(1):16. doi: 10.1186/s13028-020-00514-6.
Oestrous synchronisation of cattle has been widely applied to accomplish simultaneous ovulation in animals and facilitate timed artificial insemination. The main aim of this study was to investigate the ovarian follicular growth and ovulatory response to oestrus and ovulation synchronisation in Norwegian Red heifers and cows. Oestrous cycles in 34 heifers and 10 cows from 4 herds were synchronised with two PGF analogue treatments 11 days apart, followed by GnRH analogue treatment for induction of ovulation. Thereafter, the ovaries were examined by ultrasonography at 3 h intervals until ovulation.
The luteolytic effect of the PGF analogue was verified in 9 of 10 cows by progesterone contents in milk. Maximum physical activity of the cows occurred on average 69 h after PGF analogue treatment. An ovulatory response was recorded in 95.5% (42/44) of the animals. A significant difference in follicle size at ovulation was found between 2 of the herds. Animals with medium sized and large follicles and heifers aged > 16 months ovulated earlier than other animals.
The applied sequence of treatments in the study was shown to be effective in synchronizing and inducing ovulation within a relatively narrow time interval in the Norwegian Red heifers and cows, consistent with findings in other cattle breeds.
牛的发情同步已被广泛应用于实现动物同期排卵，便于定时人工授精。本研究的主要目的是研究挪威红牛小母牛和母牛的卵巢卵泡生长和发情排卵同步对发情和排卵同步的反应。来自 4 个牛群的 34 头小母牛和 10 头母牛的发情周期通过相隔 11 天的两次 PGF 类似物处理进行同步，然后用 GnRH 类似物处理诱导排卵。此后，通过超声检查每隔 3 小时检查一次卵巢，直到排卵。
通过牛奶中的孕激素含量，在 10 头母牛中的 9 头验证了 PGF 类似物的溶黄体作用。牛的最大生理活动平均在 PGF 类似物处理后 69 小时发生。记录到 95.5%（42/44）的动物有排卵反应。在 2 个牛群中发现了排卵时卵泡大小的显著差异。中等大小和大卵泡的动物和年龄>16 个月的小母牛比其他动物排卵更早。
研究中应用的治疗方案在挪威红牛小母牛和母牛中被证明在相对较短的时间间隔内有效同步和诱导排卵，与其他牛种的发现一致。
