Study links maternal stress history to later immune changes in sows: full analysis

New research in Animals is examining a question with clear herd-health implications: how maternal stress, plus repeated stress exposure across life stages, may shape immune phenotype and stress reactivity in sows later in life. The study, titled Effects of Maternal and Cumulative Stress on Immune Phenotype and Stress Reactivity in Sows Later in Life, focuses on prenatally stressed gilts followed across later reproductive stages, an area that remains less studied than early-life piglet outcomes. The work fits into a broader research program from Oklahoma State University on prenatal stress programming in swine. (academic.oup.com)

That background matters because most earlier swine literature has centered on piglets, not adult females that were themselves exposed to prenatal stress. Earlier studies found that maternal stress during gestation can impair both humoral and cellular immune responses in neonatal pigs, and a 2009 study reported that late-gestation maternal stress had moderate but lasting immune effects in piglets. More recent work from the same Oklahoma State group showed that the timing of gestational stress changes offspring outcomes, with mid-gestation exposure associated with reduced immunoglobulins and interleukin-4, alongside a more pro-inflammatory phenotype marked by higher IL-17 and TNF-α. (pubmed.ncbi.nlm.nih.gov)

The 2024 Journal of Animal Science abstract from Hernandez, Main, and Salak-Johnson helps fill in that trajectory. In that study, 11 primiparous females were grouped according to whether their dams had received placebo or hydrocortisone acetate during mid- or late gestation. The researchers reported elevated lymphocyte numbers in gilts from late-gestation-stressed dams, but few other maternal immune differences during gestation. However, the offspring of mid-gestation-stressed dams showed signs consistent with altered immune programming after weaning, including a higher neutrophil-to-lymphocyte ratio and lower lymphocyte measures, leading the authors to conclude that programming effects may be more visible in later generations. (academic.oup.com)

The newly cited Animals paper appears to extend that line of inquiry by looking at prenatally stressed second-parity sows and comparing them with other groups across multiple sampling points. Based on the abstract provided, the study evaluates prenatal stress, maternal stress history, and repeated stress exposure together, with endpoints tied to immune phenotype and HPA-axis-related stress reactivity. Even without the full article text available through search, that framing is notable because it moves from a single prenatal insult model toward cumulative stress biology, which is closer to what veterinarians and production teams see on farm. The related Oklahoma State dissertation record also emphasizes interest in how stress timing and cumulative exposure affect adulthood, pregnancy, immunity, and microbiome-linked outcomes. (openresearch.okstate.edu)

Outside experts weren’t readily available in direct reaction pieces to this specific paper, but the wider field has been pointing in the same direction. A 2022 Frontiers in Veterinary Science review concluded that chronic stress in sows can suppress immunity, impair reproduction, and alter offspring stress coping and disease susceptibility. The review also highlights why interpretation is tricky: cortisol alone doesn’t capture the full biology of chronic stress, and individual variation, housing, social dynamics, and coping style all likely shape outcomes. That caution is useful when translating controlled experimental findings into commercial settings. (frontiersin.org)

Why it matters: For veterinary professionals, this is less about a single biomarker and more about risk architecture. If maternal stress history influences immune phenotype later in life, then gilt development, gestation management, housing stress, mixing events, and repeated inflammatory or social challenges may have effects that surface well beyond farrowing. That could influence susceptibility patterns, vaccine responsiveness, recovery from routine production stressors, and the consistency of replacement females entering the breeding herd. The possibility that some effects emerge more clearly in progeny, rather than the directly exposed sow, also matters for herd-level decision-making. (academic.oup.com)

For swine veterinarians advising clients, the practical implication is to keep maternal environment in the conversation alongside nutrition, genetics, and biosecurity. Research on sow stress doesn’t yet translate into a simple diagnostic threshold or intervention algorithm, but it does support minimizing avoidable chronic stressors during gestation, especially during sensitive developmental windows. The literature also suggests that “when” stress occurs may be as important as “whether” it occurs. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next thing to watch is whether the full Animals publication reports actionable differences in cortisol or DHEA-S patterns, leukocyte subsets, parity effects, or reproductive outcomes, and whether future studies connect these immune and stress phenotypes to clinical endpoints such as morbidity, piglet viability, or treatment rates. (academic.oup.com)