Department of Animal Science, Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo, Piracicaba, SP, 13418-900, Brazil.
CEVA Sante Animale, Libourne, France.
Theriogenology. 2022 Jan 15;178:77-84. doi: 10.1016/j.theriogenology.2021.11.005. Epub 2021 Nov 11.
This study aimed to evaluate the progesterone (P4) release profile provided by four commercially available intravaginal P4 devices, as well as the effect of circulating P4 concentrations exclusively from these devices on the development of the dominant follicle (DF) in Nelore (Bos indicus) cows. Therefore, non-lactating multiparous Nelore cows were enrolled in an experimental design, over three replicates, starting on Day -9 with the insertion of a reused P4 device (2 g - original P4 load) for 7 d, followed by two treatments of cloprostenol sodium (PGF; 0.482 mg), 24 h apart, on Days -3 and -2. Just before device removal, on Day -2, a norgestomet ear implant was inserted and, 2 d later (Day 0), at the time of norgestomet withdrawal, cows were randomly assigned to receive one of the intravaginal devices: Primer (0.5 g); Prociclar (0.75 g); Sincrogest (1 g); or CIDR (1.9 g), and 2 mg of estradiol benzoate (EB) im. Blood samples were collected immediately before P4 device insertion, 12 h later and daily over 15 d (1 d after P4 device removal). Ultrasound examinations were performed on Days 0, 7, 8, 9, 10, 12, and 14 to evaluate ovarian dynamics. Results are presented as mean ± SEM and differences were considered when P ≤ 0.05. Overall, the devices resulted in distinct circulating P4 concentrations over 10 d, varying according to their initial P4 load and P4 impregnated surface area. Primer provided the lowest circulating P4 concentrations over time, whereas, CIDR had the greatest concentration. Sincrogest and Prociclar were similar, producing intermediary circulating P4. There was no effect of treatment on the DF diameter on any specific day, nor on follicular growth rate from Day 7-10. However, the Primer device resulted in a greater mean DF diameter over time. Additionally, greater circulating P4 concentrations, mainly during the first 3 d of device insertion, were associated with smaller DF diameters regardless of the treatment. In conclusion, results from this study provided a better understanding of the P4 profile of intravaginal P4 devices, as well as, their effect on DF development in Bos indicus cows. These data contribute to optimize the use of P4 devices in the reproductive management of beef cattle.
本研究旨在评估四种市售阴道孕酮（P4）释放曲线，并研究这些孕酮释放曲线对非泌乳经产荷斯坦牛（Bos indicus）优势卵泡（DF）发育的影响。为此，我们招募了非泌乳经产的荷斯坦牛，开展了一项三重复的实验设计，于第-9 天开始，将一枚重复使用的 P4 释放装置（2 g，初始 P4 负载）插入阴道，持续 7 天，随后于第-3 天和第-2 天分别使用氯前列烯醇钠（PGF；0.482 mg）处理 24 小时。在装置取出前的第-2 天，插入一个左炔诺孕酮埋植剂，两天后（第 0 天），在撤去左炔诺孕酮埋植剂时，牛随机接受以下四种阴道装置之一：Primer（0.5 g）、Prociclar（0.75 g）、Sincrogest（1 g）或 CIDR（1.9 g），并肌肉注射 2 mg 苯甲酸雌二醇（EB）。在 P4 释放装置插入前、12 小时后以及随后的 15 天内（P4 释放装置取出后 1 天）每天采集血液样本。在第 0、7、8、9、10、12 和 14 天进行超声检查，以评估卵巢动态。结果以均数±SEM 表示，当 P 值≤0.05 时，认为存在差异。总的来说，这些装置在 10 天内产生了不同的循环 P4 浓度，这取决于它们的初始 P4 负载和 P4 浸渍表面积。Primer 随着时间的推移提供了最低的循环 P4 浓度，而 CIDR 具有最高的浓度。Sincrogest 和 Prociclar 相似，产生中等循环 P4。在任何特定的日子里，处理对 DF 直径都没有影响，也没有影响从第 7 天到第 10 天的卵泡生长速度。然而，Primer 装置随着时间的推移产生了更大的平均 DF 直径。此外，更大的循环 P4 浓度，主要在装置插入的前 3 天，与较小的 DF 直径有关，而与处理无关。总之，本研究结果更好地理解了阴道 P4 装置的 P4 释放曲线及其对 Bos indicus 牛 DF 发育的影响。这些数据有助于优化在肉牛生殖管理中 P4 装置的使用。
