Location: Food Safety and Enteric Pathogens ResearchTitle: Short transportation did not impact circulating cortisol levels or leukocyte abundance in cattle
Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2023
Publication Date: N/A
Technical Abstract: Cattle are the primary reservoirs of Shiga toxin-producing E. coli, a foodborne pathogen, and stress events such as transportation can increase fecal shedding of STEC, presenting an increased contamination risk of the carcass and/or environment. Our objective was to understand the impact of transportation on host parameters to help understand the interplay between the host mucosal immune system, nervous system, and intestinal microbiome. Market weight heifers were maintained on pasture and half (n=12) were loaded onto a trailer and transported for 2 hours (approximately 100 miles) to mimic transportation stress before slaughter. The remaining non-transported animals (n=12) were held in a field barn for a similar amount of time. Blood was collected from transported cows at 0 (before transportation), and all cattle at 0.5, 5, 24, and 72 hours post-transport/mock transport. Serum cortisol levels were measured by ELISA and an 8-color flow cytometry panel was developed to enumerate various whole blood cell populations. Serum cortisol levels are a common measure of stress; however, no significant differences were detected in transported cattle compared to non-transported controls at any time point measured. Similarly, no differences in circulating granulocytes, neutrophils, gdT-cells, B-cells, abT-cell, or monocytes were detected. Additionally, mean fluorescence intensity and the number of cells expressing the cell trafficking and homing molecule, L-selection (CD62L), was measured for each population. Expression of CD62L fluctuated slightly over time, but no significant differences between treatment groups were observed. Serum cortisol levels and alterations in whole blood cell populations may not serve as markers for stress in cattle as a result of transportation. Additional parameters such as serum cytokine levels are being assessed as markers for transportation stress in cattle.