Cox J F, Navarrete F, Carrasco A, Dorado J, Saravia F
Department of Animal Science, Faculty of Veterinary Sciences, Universidad de Concepción, Avda. Vicente Méndez 595, Chillán, Chile.
Department of Animal Science, Faculty of Veterinary Sciences, Universidad de Concepción, Avda. Vicente Méndez 595, Chillán, Chile.
Theriogenology. 2019 Jan 1;123:159-166. doi: 10.1016/j.theriogenology.2018.10.003. Epub 2018 Oct 3.
This study used a comparative approach to gather clinical information to assess the effect of bovine somatotropin (bST) on follicular dynamics and ovulation in sheep and goats during an interovulatory cycle. The performance of general markers of ovarian function and specific features of follicular dynamics obtained by daily ultrasonography (US) were used to assess the hypothesis that bST, associated with supraphysiological levels of IGF-I, was able to disrupt the follicular dynamics and ovulation in Highlander ewes and Saanen goats. In Exp 1, 15 ewes and 14 goats were estrous-synchronized (P-6 days + PGFα d-6) and then allocated to a bST-treated group (50 and 100 mg, Lactotropin; n = 5 females each) and to an untreated control group (5 ewes and 4 goats) to assess the activity of bST through plasma IGF-I (RIA). In Exp 2, 12 animals from each species were synchronized. At day 6, they were divided into a bST-group (100 mg in sheep and 50 mg in goats, n = 6 each) and an untreated control group (n = 6 each). Starting at day 6 and up to 22 days after ovulation in sheep and 25 days in goats, each female was subjected to daily US (10 mHz probe) to assess follicular and luteal (CL) dynamics and ovulation. This included assessments of both general ovarian features and specific follicular wave features. Our results showed that bST increased plasma IGF-I by day 3 (p < 0.01) when compared to the control group. Moreover, these concentrations were maintained for at least 10 days in sheep and 10 days in goats before returning to pre-treatment concentrations. Increases in IGF-I after bST doses were similar in terms of a daily and total amount (P > 0.10). Results from Exp.2 indicate that in sheep, bST administration had a subtle inhibitory effect on follicular function. However, bST in goats had a stronger influence, extending the interovulatory cycle (P = 0,034), increasing the number of follicular waves during the period (P = 0.003), and reducing the functional potential of large follicles as measured by their lower follicular diameter (P = 0.02), duration of the follicle waves (P = 0.02), and persistence of follicles after reaching their maximum diameters (P = 0.04). In addition, untreated sheep and goats shared common patterns of terminal follicular development and ovulations characterized by overlapping between follicular waves and ovulations of follicles from different waves, features not seen in cattle.
本研究采用比较方法收集临床信息，以评估牛生长激素（bST）对绵羊和山羊在排卵间期卵泡动态和排卵的影响。通过每日超声检查（US）获得的卵巢功能一般标志物的表现和卵泡动态的特定特征，用于评估以下假设：与超生理水平的胰岛素样生长因子-I（IGF-I）相关的bST能够扰乱高地母羊和萨能山羊的卵泡动态和排卵。在实验1中，15只母羊和14只山羊进行发情同步处理（P-6天 + 前列腺素Fα d-6），然后分为bST处理组（50和100 mg，促乳素；每组n = 5只雌性）和未处理对照组（5只母羊和4只山羊），通过血浆IGF-I（放射免疫分析）评估bST的活性。在实验2中，每个物种的12只动物进行同步处理。在第6天，它们被分为bST组（绵羊100 mg，山羊50 mg，每组n = 6只）和未处理对照组（每组n = 6只）。从第6天开始，直到绵羊排卵后22天和山羊排卵后25天，对每只雌性进行每日超声检查（10 mHz探头），以评估卵泡和黄体（CL）动态及排卵情况。这包括对卵巢一般特征和特定卵泡波特征的评估。我们的结果表明，与对照组相比，bST在第3天时使血浆IGF-I升高（p < 0.01）。此外，这些浓度在绵羊中至少维持10天，在山羊中维持10天，然后才恢复到处理前的浓度。bST剂量后IGF-I的增加在每日量和总量方面相似（P > 0.10）。实验2的结果表明，在绵羊中，施用bST对卵泡功能有轻微的抑制作用。然而，bST对山羊的影响更强，延长了排卵间期（P = 0.034），增加了该期间卵泡波的数量（P = 0.003），并通过较小的卵泡直径（P = 0.02）、卵泡波持续时间（P = 0.02）以及卵泡达到最大直径后的持续存在时间（P = 0.04）来衡量，降低了大卵泡的功能潜力。此外，未处理的绵羊和山羊具有共同的终末卵泡发育和排卵模式，其特征是卵泡波之间以及来自不同波的卵泡排卵之间存在重叠，这是牛中未观察到的特征。
