Location: Livestock Issues ResearchTitle: Steers inoculated with Salmonella exhibit dissimilar hematology and rectal temperature profiles based on their exposure to dexamethasone
|WILKERSON, SHANNON - Auburn University|
|Carroll, Jeffery - Jeff Carroll|
|TIGUE, D.ALEX - Auburn University|
|REHM, JOHN - Auburn University|
|CALLAWAY, TODD - University Of Georgia|
|BRATCHER, CHRISTY - Auburn University|
Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/2/2018
Publication Date: 7/29/2019
Citation: Wilkerson, S., Broadway, P.R., Carroll, J.A., Sanchez, N.C., Tigue, D., Rehm, J., Callaway, T.R., Bratcher, C.L. 2019. Steers inoculated with Salmonella exhibit dissimilar hematology and rectal temperature profiles based on their exposure to dexamethasone. American Society of Animal Science Southern Section Meeting. 97(Suppl 1):44-45.
Technical Abstract: The objective of this study was to determine the effects of daily dexamethasone (DEX) infusions on hematology and rectal temperature (RT) responses to oral inoculation with Salmonella Typhimurium. Weaned Holstein steer calves (n=20; BW=102±2.7 kg BW) received DEX (n=10; 0.5mg/kg BW) or saline (CON; n=10; 0.5mg/kg BW) i.v. for 4 d from -24 to 48 h and relative to oral inoculation with a naldixic acid resistant Salmonella Typhimurium (3.4x106 CFU/animal) via milk replacer on d 0. Fecal swabs for SAL shedding were obtained daily and samples were confirmed positive starting 24 h post inoculation to harvest (120 h). DEX administration was achieved via indwelling jugular catheters which were fitted simultaneously with rectal temperature (RT) recording devices on d -2 relative to inoculation and placed in individual pens in an environmentally controlled facility. Whole blood was collected at -24, -12, and 0 h, and at 8-h intervals from 8 to 120 h for analysis of hematology. There was a time x treatment interaction (There should be) for RT such that the DEX treatment decreased RT from -24 to 48 h. A treatment × time interaction (P < 0.05) was observed for total white blood cells (WBC), neutrophils, lymphocytes, eosinophils, and monocytes. Specifically, DEX increased (P < 0.0001) total WBC and neutrophils in DEX steers compared to CON,yet DEX increased lymphocytes (P < 0.05 at 24 and 48 h, respectively) compared to CON. Monocytes initially increased (P < 0.001) in response to the -24 h DEX treatment but counts slowly decreased beyond the CON group following the 48 h DEX treatment. Based on these data, daily DEX administration may have mimicked multiple acute stressors, caused mild immunosuppression, or a combination of both scenarios relative to the Salmonella inoculation.