Transportation of young beef bulls alters circulating physiological parameters that may be effective biomarkers of stress

¹ School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland; Teagasc, Grange Beef Research Centre, Dunsany, County Meath, Ireland; Department of Animal Science, Michigan State University, East Lansing, MI 48824
² Department of Animal Science, Michigan State University, East Lansing, MI 48824
³ Teagasc, Grange Beef Research Centre, Dunsany, County Meath, Ireland
⁴ School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland

^* To whom correspondence should be addressed. E-mail: Bernadette.Earley{at}teagasc.ie.

	Abstract

Transportation causes stress in cattle that may alter numerous physiological variables with a negative impact on production and health. The objectives of the current study were to investigate the physiological effects of truck transportation and to characterize a pattern of phenotypes in the circulation that may aid in the early identification of stress-susceptible animals that often succumb to severe respiratory disease. Thirty-six young beef bulls (Aberdeen Angus, n = 12; Friesian, n = 12; and Belgian Blue x Friesian, n = 12) were subjected to a 9-h truck transportation by road. Blood (10 mL) was collected at -24, 0, 4.5, 9.75, 14.25, 24, and 48 h relative to initiation of transportation (0 h). Plasma was collected for the assay of various metabolic, inflammatory, and steroid variables, and total leukocyte counts were determined in whole blood at each time point. Body weight and rectal temperature were recorded at -24, 9.75, and 48 h. Transportation decreased measures of protein metabolism in the plasma, including albumin (P = 0.002), globulin (P < 0.001), urea (P = 0.006), and total protein (P < 0.001), and increased creatine kinase (P < 0.001). The energy substrate -hydroxybutyrate (HB) was not changed (P = 0.27). Acute phase proteins haptoglobin and fibrinogen were both decreased (P < 0.001), while total leukocyte counts were elevated (P = 0.002). Circulating steroid concentrations were altered as a classical acute increase in plasma cortisol was observed with the onset of transit (P < 0.001) in association with a decrease in dehydroepiandrosterone (DHEA; P = 0.07), resulting in a profound increase in cortisol:DHEA ratio (P < 0.001). Plasma testosterone was decreased, while plasma progesterone was increased (P < 0.001) in association with the increase in cortisol (P < 0.001). There was also an effect of breed for all variables except plasma urea, creatine kinase, and testosterone, perhaps indicating that a genetic component contributed to the physiological response to transportation stress, although without any clear trend. Taken together, this profile of physiological variables in the circulation of transportation-stressed bulls may aid in the future detection of disease-susceptible cattle following transportation. Further research to validate these potential biomarkers is necessary.

Key Words: beef cattle, biomarkers, disease, physiology, plasma, transportation stress