Non-invasive monitoring of adrenocortical function in female domestic pigs using saliva and faeces as sample matrices

PLoS One. 2020 Jun 25;15(6):e0234971. doi: 10.1371/journal.pone.0234971. eCollection 2020.

Abstract

Intensive pig management involves in a commercial setting the housing and implementation of certain procedures, such as castration and tail docking, which may be stressful for the animal. Good farming practices include the reduction of stress due to management processes, but assessing the level of stress perceived entirely through behavioural observations can be challenging. The monitoring stress-related physiological markers, like glucocorticoids (GC), can be an accurate alternative that would presumably be more objective. In order to avoid an additional stressor by taking blood, a non-invasive approach is advisable. We used an adrenocorticotropic hormone (ACTH) stimulation test and the effect of transport to examine the suitability of different enzyme immunoassays (EIAs) for monitoring adrenocortical function in domestic pigs using saliva and faeces as sample matrices. An assay measuring faecal glucocorticoid metabolites (fGCMs) with a 3ß,11ß-diol group has proven suited to determine adrenocortical activity, showing an overall increase of 180% in fGCM concentrations related to ACTH administration and of 70% related to transport, respectively. A cortisol EIA was used to detect salivary glucocorticoid (sGC) concentrations, revealing a 1100% increase in sGC concentrations after ACTH administration. The stability of fGCM concentrations post-defecation was determined to assess possible changes in measured fGCM concentrations in unpreserved faecal material over time, with fGCM concentrations being relatively stable (maximal 12% change) under natural conditions for approximately two days after defecation. This implicates that untreated faecal material from pigs can be analysed for up to two days after collection without appreciable level of depreciation in fGCM concentrations. Being able to assess the physiological stress response of domestic pigs non-invasively can help to improve the well-being of commercially reared pigs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Cortex / metabolism
  • Adrenocorticotropic Hormone / analysis*
  • Adrenocorticotropic Hormone / metabolism
  • Animal Husbandry / methods
  • Animal Welfare*
  • Animals
  • Circadian Rhythm / physiology
  • Feces / chemistry
  • Female
  • Hydrocortisone / analysis*
  • Hydrocortisone / metabolism
  • Saliva / chemistry
  • Stress, Physiological*
  • Sus scrofa*

Substances

  • Adrenocorticotropic Hormone
  • Hydrocortisone

Grants and funding

Funding for this work was provided partly by the National Research Foundation Incentive funding for Rated Researchers (2016) provided to Fasina FO. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.