Guimarães da Silva Amanda, Nishimura Thiago Kan, Rocha Cecília Constantino, Motta Igor Garcia, Laurindo Neto Adomar, Ferraz Priscila Assis, Bruni Gabriela Andrade, Orlandi Raphael Evangelista, Massoneto João Paulo Martinelli, Pugliesi Guilherme
USP - Universidade de São Paulo, Avenida Duque de Caxias Norte 225, Jardim Elite, Brazil.
Reproduz - Reproduz Assessoria Pecuária Cocalinho, Mato Grosso, Brazil.
Theriogenology. 2022 May;184:41-50. doi: 10.1016/j.theriogenology.2022.02.025. Epub 2022 Feb 28.
We aimed to compare the effects of use of 1 or 2 mg estradiol benzoate (EB) associated with an intravaginal progesterone (P4) device for resynchronization of ovulation 14 days after timed-AI (TAI) in suckled beef cows. Nelore cows were submitted to a TAI (D0) and on D14, received an intravaginal P4 device and were randomly assigned to EB-1 group [n = 516] or EB-2 group [n = 510], which that received 1 or 2 mg EB, respectively. Also, cows had the ovaries scanned by ultrasound to detect an active CL on D14. On D22, devices were removed and structural luteolysis was detected by color-Doppler ultrasonography. In cows which underwent luteolysis, the resynchronization protocol was continued and they were submitted to second TAI on D24. Pregnancy diagnosis was performed 30-35 days after first or second TAI. A subgroup [n = 18-19/group] was submitted to daily ovarian ultrasound scanning from D14 to D22. Proportion of cows with an active CL on D14 did not differ (P > 0.1) between EB-1 and EB-2 groups. The proportion of cows with an active CL on D22 and pregnancy per AI (P/AI) at first TAI were greater (P ≤ 0.05) in EB-1 (55% and 51%) than in EB-2 group (48% and 42%). The P/AI at second TAI did not differ (P > 0.1) between EB-1 (47% [106/227]) and EB-2 group (42% [110/259]). Cumulative pregnancy rate was greater in EB-1 (73% [370/508]) than in EB-2 group (64% [322/502]). No difference (P > 0.1) was observed in the proportion of non-pregnant cows with a synchronized follicular wave emergence between EB-1 and EB-2 groups. In conclusion, treatment with either 1 or 2 mg EB associated with an intravaginal P4 device at D14 after TAI are efficient to synchronize a new follicular wave emergence. The decreased P/AI from first TAI observed in the group of cows receiving 2 mg indicates that this dose is not recommended for use in resynchronization programs initiated 14 days after TAI. The use of 1 mg EB associated with a P4 device provides an elevated cumulative pregnancy rate after two TAIs with an interval of 24 days.
我们旨在比较在哺乳期肉用母牛定时人工授精（TAI）后14天，使用1毫克或2毫克苯甲酸雌二醇（EB）联合阴道内孕酮（P4）装置对排卵再同步化的影响。内洛雷牛接受TAI（第0天），并在第14天接受阴道内P4装置，然后被随机分配到EB-1组[n = 516]或EB-2组[n = 510]，分别接受1毫克或2毫克EB。此外，在第14天对母牛进行超声扫描卵巢以检测活性黄体（CL）。在第22天，取出装置，并通过彩色多普勒超声检测黄体结构溶解。对于发生黄体溶解的母牛，继续再同步化方案，并在第24天对它们进行第二次TAI。在第一次或第二次TAI后30 - 35天进行妊娠诊断。一个亚组[n = 18 - 19/组]在第14天至第22天每天进行卵巢超声扫描。EB-1组和EB-2组在第14天有活性CL的母牛比例没有差异（P > 0.1）。在EB-1组（55%和51%）中，第22天有活性CL的母牛比例和第一次TAI时的每人工授精妊娠率（P/AI）高于EB-2组（48%和42%）（P≤0.05）。EB-1组（47% [106/227]）和EB-2组（42% [110/259]）在第二次TAI时的P/AI没有差异（P > 0.1）。EB-1组（73% [370/508]）的累积妊娠率高于EB-2组（64% [322/502]）。EB-1组和EB-2组之间，未怀孕且卵泡波同步出现的母牛比例没有差异（P > 0.1）。总之，在TAI后第14天，使用1毫克或2毫克EB联合阴道内P4装置进行治疗，对于使新的卵泡波同步出现是有效的。在接受2毫克EB的母牛组中，观察到第一次TAI时P/AI降低，这表明该剂量不推荐用于TAI后14天开始的再同步化方案。使用1毫克EB联合P4装置在间隔24天的两次TAI后可提供较高的累积妊娠率。
