Effect of blood sampling and shipment to slaughter on plasma catecholamine concentrations in bulls

The effect of venipuncture on blood serum catecholamine concentrations was studied in five yearling Red Angus bulls. Treatments consisted of sampling jugular vein blood via indwelling cannulas in a squeeze chute every 10 min for 1 h; sampling jugular vein blood from an indwelling catheter before, during and after venipuncture simulation; sampling jugular vein blood by venipuncture in a chute after shipment of 320 km to a slaughter plant; and sampling pooled blood from the neck during exsanguination at slaughter. Plasma epinephrine (E) and norepinephrine (NE) concentrations were determined by high performance liquid chromatography (HPLC) with electrochemical detection (ECD). Prevenipuncture NE and E in blood sampled from an indwelling catheter extended through a solid wall were 1.0 and .5 pmol/ml plasma, respectively. Plasma NE and E during venipuncture (1.6 and 1.1 pmol/ml, respectively) and immediately after cannulation in a squeeze chute (1.8 and 1.2 pmol/ml, respectively) were higher than prevenipuncture concentrations. Plasma NE and E, 1.9 and 1.2 pmol/ml plasma after shipment of 320 km, increased during exsanguination to 135.8 and 81.3 pmol/ml plasma, respectively. The NE and E in blood samples collected by venipuncture in a chute or box stall do not represent resting concentrations of these catecholamines.