Location: Livestock Behavior ResearchTitle: The effects of orally administered cortisol and norepinephrine on weanling piglet gut microbial populations and Salmonella passage Author
Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2018
Publication Date: N/A
Interpretive Summary: Weaning is an anxiety-provoking event that all production piglets experience. Methods to reduce the severity and duration of this stress are needed. Anxiety, and other negative affective states influence the microorganisms living in the gut. An increase in stress and anxiety and impairments in learning and memory have been associated with infection and other changes from the normal gut. Therefore, an anxiety-like state, as observed in piglets during weaning, may be changing the gut microbiome and susceptibility to disease. The impact of stress hormones on microbial communities of the gut is not known. Therefore the objective of this study was to observe intestinal microbiota and susceptibility to Salmonalla associated with anxiety-like states (created with oral stress hormones) in piglets. At weaning, piglets were trained to take apple juice (the carrier) orally. At two weeks post-weaning, pens of piglets were given apple juice only, control; apple juice with norepinephrine (the fight or flight hormone), or cortisol (stress hormone). In general, pathogenic bacteria are mostly aerobic and beneficial bacteria are mostly anaerobic. The oral administration of norepinephrine and cortisol had the desired effect of increasing concentrations of the stress hormones in the body. Administration of treatments also resulted in microbiota shifts throughout the intestines. High E. coli populations and low lactic acid bacteria producing populations indicate that the oral administration of cortisol may have resulted in opportunistic infections. Piglets treated with norepinephrine exhibited an increase in anaerobes and lactic acid producing bacteria. It appears that anxiety-like states in piglets, like many other species, result in shifts in the intestinal microbial community.
Technical Abstract: Weaning is an anxiety-provoking event that all production piglets experience. The objective of this study was to observe intestinal microbiota and susceptibility to Salmonalla associated with anxiety-like states in piglets. Ninety pigs were grouped by weight into 15 pens of 8 piglets. At weaning, piglets were trained to take the carrier (apple juice) orally. At two weeks post-weaned, pens of piglets were randomly assigned to one of three treatments: control (CNT), norepinephrine (NE), or cortisol (CORT). Blood samples were collected prior to treatments. Piglets were dosed orally with treatments twice on day 0; at 0800 and 1600 h. Control piglets were administered 6.1 mL of the carrier only, NE pigs were administered 40 mg/mL of norepinephrine-bitartrate salt dissolved in the carrier, and CORT pigs were administered 12 mg/mL of hydrocortisone acetate dissolved in the carrier. Blood samples were collected prior to necropsies. Necropsies were performed at days 0.5, 1, 2, 7, and 14. Jejunal and ileal tissues and jejunal, ileal, cecal, and rectal contents were collected and colonies counted. All data were analyzed with SAS 9.4. Microbial data and blood samples were analyzed using mixed models with fixed effects of treatment and day. Cortisol treated piglets exhibited a spike in plasma cortisol concentrations and a shift in intestinal environment to favor aerobes and pathogens. Norepinephrine treated piglets exhibited a lasting spike in norepinephrine concentrations and a shift in intestinal environment to favor anaerobes and facultative anaerobes.