Influence of temperament and transportation on physiological and endocrinological parameters in bulls
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This study measured physiological, immunological, and endocrinological responses of Bos indicus cattle of differing temperaments to transportation. Based on temperament score (TS) the 7 most Calm (TS = 0.84 0.03) and 8 most Temperamental (TS = 3.37 0.18) Brahman bulls were selected from our research herd. Prior to transportation bulls were fitted with heart rate monitors, indwelling jugular vein catheters, and rectal temperature recording devices that enabled continuous collection of data and samples during transport. The bulls were loaded into individual stalls in a trailer, and each catheter extension was attached to an IceSampler device that was programmed to collect blood samples at 15- and 30-min intervals. The trailer remained stationary for 120. min prior to the initiation of transportation to acclimate bulls to the stalls. The bulls were then transported for 4. h (390. km roundtrip; average of 91. km/h). Collected blood samples were analyzed for cortisol, epinephrine, and norepinephrine. Additional blood samples were collected for isolation of peripheral blood mononuclear cells (PBMCs) to determine proliferation, IgM production, and gene expression. Heart rate fluctuated in Temperamental but not in Calm bulls throughout the study (time temperament interaction P= 0.04). Rectal temperature increased over time (p<0.001) but was not affected by temperament (P=0.57). Change in rectal temperature may be partially attributable to the change in ambient temperature as the two were highly correlated (r = 0.73 and 0.72 for Calm and Temperamental bulls, respectively; p<0.001). Cortisol concentrations increased in Calm but not Temperamental bulls in response to transportation (time temperament interaction P=0.01). Epinephrine concentrations were unchanged in Calm but decreased in Temperamental bulls (time temperament interaction P=0.07) throughout the study. Norepinephrine concentrations were not affected by transportation (P=0.36) or temperament (P=0.93). The production of IgM by PBMCs was not affected by temperament (P=0.40) or transportation (P=0.28). Proliferation of PBMCs was not affected by temperament (P=0.98) but tended (P=0.06) to be greater post-transportation. The expression of the glucocorticoid receptor (P=0.02) and toll-like receptor 4 (P=0.08) mRNAs decreased in response to transportation. In summary, these data indicate that transportation only affected cortisol concentrations in Calm bulls. Additionally, temperament influenced cortisol and epinephrine concentrations as well as heart rate. However, there was no influence of temperament, and limited influence of transportation, on PBMC functions. While transportation has been purported to be a stressor in cattle, the temporal pattern observed while the bulls were on the trailer is suggestive that the stress occurred prior to loading the bulls into the trailer. 2011 Elsevier B.V.