An increase in plasma concentrations of cortisol is one signal that begins parturition and uterine contractions in pregnant sows; however, it is not known whether a critical level of cortisol is necessary or the role that it may play in the duration of parturition. The objective of the study was to characterize plasma concentrations of during the periparturient period and assess its relationship with initiation of parturition, litter size, and farrowing duration. Blood was collected via indwelling catheters from 5 primiparous gilts twice daily (0700 and 1900 h) from d113 of gestation until the birth of the first piglet, after which blood was collected every 15 minutes until farrowing was considered complete. Time of birth of each piglet was recorded. Farrowing duration was defined as the time between birth of the first and last piglets. Plasma concentrations of cortisol were determined by radioimmunoassay. Litter size was 12, 12, 18, 17, and 14 piglets and farrowing duration was 72 minutes, 4.1, 6.7, 5.8, and 4 hours, respectively. Quadratic and linear regressions were performed using the RStats package in RStudio (version 1.2.5025). Serum concentrations of cortisol were 3.37 ± 1.55 and 5.73 ± 2.18 ng/mL prior to parturition and at the birth of the first piglet, respectively. There was a positive quadratic relationship (P ≤ 0.07) between time of birth of each piglet and plasma cortisol levels; peak cortisol was 14.45 ± 3.20 ng/mL. There was a positive correlation between initial cortisol level and average piglet birth weight (P = 0.0124) but no relationship with total litter weight (P > 0.05). Determination of the periparturient changes in cortisol may be useful in designing farrowing induction protocols.

中文翻译：

---

288 后备母猪围产期血浆皮质醇浓度

血浆皮质醇浓度的增加是妊娠母猪开始分娩和子宫收缩的一个信号。然而，目前尚不清楚临界水平的皮质醇是否是必要的，也不知道它在分娩期间可能发挥的作用。该研究的目的是描述围产期血浆浓度的特征，并评估其与分娩开始、窝产仔数和分娩持续时间的关系。从妊娠第 113 天到第一头仔猪出生，每天两次（0700 和 1900 小时）通过留置导管从 5 头初产后备母猪身上采集血液，之后每 15 分钟采集一次血液，直到认为分娩完成。记录每只小猪的出生时间。分娩时间定义为第一头和最后一头仔猪出生之间的时间。通过放射免疫测定法测定皮质醇的血浆浓度。窝产仔数为 12、12、18、17 和 14 头仔猪，分娩时间分别为 72 分钟、4.1、6.7、5.8 和 4 小时。使用 RStudio（版本 1.2.5025）中的 RStats 包执行二次和线性回归。分娩前和第一头仔猪出生时，血清皮质醇浓度分别为 3.37 ± 1.55 和 5.73 ± 2.18 ng/mL。每头仔猪出生时间与血浆皮质醇水平呈正二次关系（P≤0.07）；皮质醇峰值为 14.45 ± 3.20 ng/mL。初始皮质醇水平与平均仔猪出生体重呈正相关（P = 0.0124），但与总窝重无关（P > 0.05）。