Studying selection of multiple dominant follicles (DFs) in monovulatory species can advance our understanding of mechanisms regulating selection of single or multiple DFs. Carriers of the bovine high fecundity Trio allele select multiple DFs, whereas half-sib noncarriers select a single DF. This study compared follicle selection during endogenous gonadotropin pulses versus during ablation of pulses with Acyline (GnRH antagonist) and luteinizing hormone (LH) action replaced with nonpulsatile human chorionic gonadotropin (hCG) treatment in Trio carriers (n = 28) versus noncarriers (n = 32). On Day 1.5 (Day 0 = ovulation), heifers were randomized: (1) Control, untreated; (2) Acyline, two i.m. doses (Days 1.5 and D3) of 3 μg/kg; (3) hCG, single i.m. dose of 50 IU hCG on Day 1.5 followed by daily doses of 100 IU; and (4) Acyline + hCG. Treatments with nonpulsatile hCG were designed to replace LH action in heifers treated with Acyline. Acyline treatment resulted in cessation of follicle growth on Day 3 with smaller (P < 0.0001) maximum follicle diameter in Trio carriers (6.6 ± 0.2 mm) than noncarriers (8.7 ± 0.4 mm). Replacement of LH action (hCG) reestablished follicle diameter deviation and maximum diameter of DFs in both genotypes (8.9 ± 0.3 mm and 13.1 ± 0.5 mm; P < 0.0001). Circulating follicle stimulating hormone (FSH) was greater in Acyline-treated than in controls. Finally, Acyline + hCG decreased (P < 0.0001) the number of DFs from 2.7 ± 0.2 to 1.3 ± 0.2 in Trio carriers, with most heifers having only one DF. This demonstrates the necessity for LH in acquisition of dominance in Trio carriers (~6.5 mm) and noncarriers (~8.5 mm) and provides evidence for a role of GnRH-induced FSH/LH pulses in selection of multiple DFs in Trio carriers and possibly other physiologic situations with increased ovulation rate.

中文翻译：

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在给予 GnRH 拮抗剂和 LH 作用的 Trio 携带者中选择较少的优势卵泡，由非搏动 hCG 代替。†。

研究单排卵物种中多个优势卵泡 (DF) 的选择可以促进我们对调节单个或多个 DF 选择的机制的理解。牛高繁殖力 Trio 等位基因的携带者选择多个 DF，而半同胞非携带者选择单个 DF。本研究比较了在 Trio 携带者 ( n  = 28) 与非携带者 ( n = 32）。在第 1.5 天（第 0 天 = 排卵），将小母牛随机分组：（1）对照，未处理；(2) Acyline，两次肌肉注射（第 1.5 天和第 3 天）3 μg/kg；(3) hCG，第 1.5 天单次肌肉注射 50 IU hCG，然后每天注射 100 IU；(4) Acyline + hCG。非搏动 hCG 治疗旨在取代 Acyline 治疗的小母牛的 LH 作用。Acyline 治疗导致第 3 天卵泡生长停止， Trio 携带者 (6.6 ± 0.2 mm) 的最大卵泡直径小于非携带者 (8.7 ± 0.4 mm) ( P < 0.0001)。LH 作用 (hCG) 的替代在两种基因型中重新建立了卵泡直径偏差和 DF 的最大直径（8.9 ± 0.3 毫米和 13.1 ± 0.5 毫米；P < 0.0001)。Acyline 治疗组的循环促卵泡激素 (FSH) 高于对照组。最后，Acyline + hCG 将 Trio 载体中的 DF 数量从 2.7 ± 0.2 减少到 1.3 ± 0.2 （P < 0.0001），大多数小母牛只有一个 DF。这证明了 LH 在 Trio 携带者（~6.5 毫米）和非携带者（~8.5 毫米）中获得优势的必要性，并为 GnRH 诱导的 FSH/LH 脉冲在选择 Trio 携带者和其他可能的多个 DF 中的作用提供了证据排卵率增加的生理情况。