![]() ![]() ![]() In addition to direct effects of weaning, piglets are exposed to unfamiliar individuals in nursery pens, which results in aggressive encounters and skin lesion development ( Wurtz et al., 2017). Weaning represents a period of dietary and social stress in pig production systems with acute effects on digestive physiology and immune response ( Lallès et al., 2004). Livestock animals experience numerous stressors throughout their lifetime that result in short- and long-term effects on physiology and performance ( Yahav and Hurwitz, 1996 Geverink et al., 1998 Molenaar et al., 2011 Li et al., 2017 Johnson et al., 2018). Our results indicate that weaning-associated stress elicits genome-wide methylation changes associated with differential gene expression, reduced T cell activation, and an altered HPA axis response. We observed post-weaning hypermethylation of the glucocorticoid receptor ( NR3C1) promoter and a significant decrease in NR3C1 expression ( n = 9, p = 6.1 × 10 –3). ![]() Differential methylation was strongly associated with differential expression specifically, upregulated genes were enriched among hypomethylated genes. Stress groups displayed unique differential methylation and expression patterns associated with activation and suppression of T cell immunity in low and high stress animals, respectively. We identified 2,674 differentially methylated regions (DMRs) that were enriched within promoters of genes associated with lymphocyte stimulation and transcriptional regulation. Blood was collected from nine gilt piglets 24 h before and after weaning, and whole-genome bisulfite sequencing (WGBS) and RNA-sequencing were performed on six and nine animals, respectively, at both time points. We quantified changes in CpG methylation and transcript abundance in piglet peripheral blood mononuclear cells (PBMCs) following weaning and also assessed differential patterns in pigs exhibiting high and low stress response as measured by cortisol concentration and lesion scores. While differential methylation following stress has been assessed in model organisms, it remains poorly understood how the pig methylome is altered by stressors in production settings. Pig weaning is associated with dietary and social stress, both of which elicit an immune response and changes to the hypothalamic–pituitary–adrenal (HPA) axis. Therefore, the preferred sample collection method for future experiments involving periparturient sows will be ear-venipuncture, rather than salivary collection.Changes to the epigenome, including those to DNA methylation, have been proposed as mechanisms by which stress can induce long-term physiological changes in livestock species. ![]() If a treatment is expected to cause a 25% change in cortisol secretion, then only 21 sows will be needed per treatment if plasma is measured, whereas 152 pigs will be needed if saliva is measured. Nonetheless, CV% was lower among plasma than salivary samples (24.8 vs. The range of cortisol concentration was greater in the plasma-samples than the salivary samples (19.17 to 55.50 vs. Sows tended, (P = 0.06) to have less ear-vein plasma cortisol concentrations at -1 than +1 d relative to parturition but differences in cortisol concentrations were not detected from saliva samples (P = 0.67). After centrifugation, saliva and plasma were harvested from solid-particles and blood cells then immediately frozen at -20☌ until cortisol concentration analysis using a commercially available ELISA kit (Detect X Cortisol Assay Arbor Assays, Anne Arbor, MI). Sows were offered a 51 cm cotton-rope to chew on and 300 uL of blood was drawn after ear venipuncture using a 26 gauge needle and syringe treated with heparin. Samples were collected from 10 multiparous sows (DNA Genetics K-State Swine Research Center) at -1 and +1 d relative to farrowing. Therefore, the objectives of this study were to determine the variation of stress-responses to farrowing using less-invasive sample collection methods (saliva vs. Snaring can be an added stressor to sows, especially during the periparturient phase, when cortisol concentrations are already elevated and variable responses are expected. The most common method of cortisol sample collection for sows is jugular venipuncture, which requires restraint via snaring. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |