Influence of prenatal transportation stress on innate immune response to an endotoxin challenge in weaned Brahman bull calves †,‡ .

The objective of this study was to assess the influence of prenatal stress (PNS) on innate immune responses to an endotoxin challenge in weaned bull calves. Altered innate immune response to lipopolysaccharide (LPS), as characterized by changes in a range of variables was hypothesized in PNS bull calves. Brahman cows (n = 96; 48 stressed by transportation at five stages of gestation and 48 Controls) produced 85 calves, from which 16 uncastrated male (bull) calves from each PNS and Control treatment were selected for an LPS challenge period. Rectal temperature (RT), sickness behavior score (SBS), serum concentrations of cortisol, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and complete blood count (CBC) variables were assessed in response to intravenous LPS (0.25 μg/kg body weight) administration. Each reported variable increased or decreased following LPS administration. Prior to LPS, PNS bull calves exhibited increased TNF-α, IL-6, and monocyte counts, but decreased IFN-γ, eosinophils, and basophils (p < .05). Compared with Control, in response to LPS, PNS bull calves exhibited greater circulating concentrations of cortisol. PNS bull calves exhibited lower (p < .05) eosinophil and basophil counts at time 0 (time of LPS administration) but similar counts to Control bull calves 2 h after LPS. PNS bull calves exhibited a greater change from baseline for IFN-γ and monocytes in response to LPS administration. No other variables were influenced by prenatal treatment (p > .05). These findings suggest that PNS did not adversely affect basal or induced components of the innate immune response to an immunological challenge. Lay summary Our laboratory studied the influence of prenatal stress (i.e., transportation of pregnant cows) on immune function of bull calves at 8 months of age. This was accomplished by studying aspects of their innate immune response to an immunological challenge. Prenatal stress did not adversely affect basal or induced components of the innate immune response to an immunological challenge.