Effects of Maternal and Cumulative Stress on Immune Phenotype and Stress Reactivity in Sows Later in Life

The timing and nature of gestational stress can alter offspring immune function and hypothalamic–pituitary–adrenal (HPA) axis regulation, yet the role of maternal stress history remains poorly understood. This study evaluated the effects of prenatal stress, maternal stress history, and repeated stress exposure on immune and stress reactivity in prenatally stressed (PS) gilts across two farrowings. Eleven PS second-parity sows (197.27 ± 19.22 kg) were sampled at multiple timepoints and compared with their maternally stressed (MS) dams. During the second pregnancy, PS sows received the same maternal treatment as their dams: placebo (CON) or hydrocortisone acetate (HCA) administered twice daily for 21 days during mid (M; d 51–72) or late (L; d 81–102) gestation. Data were analyzed using mixed models with repeated measures in SAS (Version 9.4). During the first pregnancy, PS gilts in the L-HCA group exhibited higher lymphocyte proliferation indices and plasma cortisol concentrations than MS dams (p < 0.05). In the second pregnancy, dehydroepiandrosterone sulfate concentrations were lower in PS sows in the M-HCA group than the CON sows (p < 0.05). Overall, cortisol concentrations were lower in PS sows than PS gilts (p < 0.05), suggesting that maternal stress history modifies physiological responses to gestational stress, though this interpretation is constrained by the small sample size.