Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, São Paulo, Brazil; Department of Animal Science, University of Florida, Gainesville, Florida, USA.
Department of Animal Science, University of Florida, Gainesville, Florida, USA; Department of Animal and Dairy Sciences and Brown Loam Experiment Station, Mississippi State University, Mississippi State, Mississippi, USA.
Theriogenology. 2022 Oct 15;192:73-80. doi: 10.1016/j.theriogenology.2022.08.033. Epub 2022 Aug 28.
The objective of this study was to compare the efficiency of estradiol benzoate (EB) and 17β-estradiol (E2) associated with progesterone (P4) in a fixed-time artificial insemination (FTAI) protocol. We hypothesized that E2+P4 induces an earlier emergence of a new follicular wave (NFW), improving pre-ovulatory follicle diameter and pregnancy rates to FTAI (P/FTAI). In Exp.1, on Day 0 (D0), all Bos indicus cows (n = 12/group) received an intravaginal P4 device and a dose of PGF2α analogue. On D0, females were randomly assigned to receive EB or E2+P4. On D8.5, P4 intravaginal devices were removed and a dose of PGF2α and EB were administered in all females followed by fixed-timed AI on D10. Between D0 and D10, the dominant follicular growth was determined by ovary ultrasonography exams. On D8.5 and D10 the percentage of color power-Doppler signals in the dominant follicular wall was evaluated. In Exp. 2, 467 females (2-year-old nulliparous [n = 76], primiparous [n = 92] and pluriparous [n = 299]) were subjected to the similar FTAI and assigned to be treated with EB (n = 243) or E2+P4 (n = 224). Pregnancy diagnosis was performed 30 days after FTAI by ultrasonography. The day to emergence of NFW was similar between treatments (EB: 3.7 ± 0.37 vs. E2+P4: 3.3 ± 0.3, P = 0.76). Females treated with E2+P4 presented greater (P = 0.06) follicular growth between the emergence and D9 (1.18 ± 0.07) than those treated with EB (0.97 ± 0.08). There was also a positive effect (P < 0.05) of E2+P4 on diameter of the dominant follicle on D9 (13.0 ± 0.6 vs. 10.9 ± 0.55) and blood perfusion of the follicle wall on D8.5 (49 vs. 40%). There was a treatment by parity category interaction effect on P/FTAI (P < 0.05). Treatment with E2+P4 was advantageous to P/FTAI of primiparous cows (E2+P4: 58% and EB: 30%). However, for nulliparous and pluriparous cows, P/FTAI was similar between treatments (∼50%). In conclusion, in a E2/P4-based protocol for FTAI, E2+P4 is as efficient as EB in inducing new follicular emergence within a similar day range, but it results similar or greater P/FTAI.
本研究旨在比较苯甲酸雌二醇（EB）和 17β-雌二醇（E2）与孕激素（P4）联合用于定时人工授精（FTAI）方案的效果。我们假设 E2+P4 可更早地引发新的卵泡波（NFW），从而提高 FTAI 前的排卵前卵泡直径和妊娠率（P/FTAI）。实验 1 中，所有印度野牛（Bos indicus）奶牛（n=12/组）在第 0 天（D0）接受阴道内 P4 装置和 PGF2α 类似物剂量。D0 时，随机将母牛分为接受 EB 或 E2+P4 治疗的两组。在 D8.5，取出阴道内 P4 装置，并给所有母牛注射 PGF2α 和 EB 剂量，随后在 D10 进行固定时间人工授精。在 D0 和 D10 之间，通过卵巢超声检查确定主导卵泡的生长情况。在 D8.5 和 D10 评估主导卵泡壁中彩色功率多普勒信号的百分比。在实验 2 中，467 头母牛（2 岁初产[n=76]、经产[n=92]和多产[n=299]）接受了类似的 FTAI，并分为接受 EB（n=243）或 E2+P4（n=224）治疗。FTAI 后 30 天通过超声检查进行妊娠诊断。两种处理方式之间新卵泡波的出现时间相似（EB：3.7±0.37 vs. E2+P4：3.3±0.3，P=0.76）。接受 E2+P4 治疗的母牛在出现和 D9 之间的卵泡生长更大（P=0.06，1.18±0.07），而接受 EB 治疗的母牛生长较小（0.97±0.08）。E2+P4 对 D9 时的主导卵泡直径（13.0±0.6 比 10.9±0.55）和 D8.5 时卵泡壁的血液灌注也有积极影响（49 比 40%）。P/FTAI 存在治疗与胎次类别的交互作用效应（P<0.05）。E2+P4 治疗对初产奶牛的 P/FTAI 更有利（E2+P4：58%和 EB：30%）。然而，对于初产和多产奶牛，两种处理方式的 P/FTAI 相似（约 50%）。综上所述，在基于 E2/P4 的 FTAI 方案中，E2+P4 在诱导新卵泡出现方面与 EB 一样高效，且在相似的时间范围内，但它导致的 P/FTAI 相似或更高。
