Effect of rest stop duration during long-distance transport on welfare indicators in recently weaned beef calves 1

Forty newly weaned beef calves (260 ± 32.6 kg) were transported 15 h in a livestock trailer (7.3 by 2.1 m) on 2 separate hauls 1 wk apart (20 calves/ haul) to evaluate the effect of rest stop duration on indicators of calf welfare. Immediately following the 15-h journey, 15 calves/haul were randomly unloaded at a feedlot and randomly assigned to 1 of 3 rest stop treatments; calves without resting time (5 calves/haul) remained on the trailer and were used as the control group. Treatments included 0- (Control [CON]), 5- (RS5), 10- (RS10), or 15-h (RS15) rest periods in pens containing ad libitum access to water and long-stem hay. Following each rest period, calves were reloaded onto the same trailer and taken on another 5-h journey, before they were unloaded at the same feedlot, for a total transport event lasting 20 h. Control calves did not have access to feed or water until the end of the 20-h transit event. Behavioral measurements included bunk attendance (min/d) and standing and lying duration (min/d) recorded for 5 h after the 20-h transport event. Physiological measurements included saliva and hair cortisol, complete blood cell count, serum NEFA, haptoglobin, and substance P concentrations. All physiological measurements as well as BW were taken immediately prior to initial loading, at arrival at the feedlot after the 20-h event, and 48 h after the transport to the same feedlot. Hair cortisol was collected prior to the initial loading and 25 d after transportation. No differences (P = 0.78) in BW loss were observed among treatments after transportation. Standing time was greater (P < 0.001) in CON calves compared with RS5, RS10, and RS15 calves. Salivary cortisol was greater (P < 0.01) in CON and RS15 calves than in RS5 and RS10 calves at the end of the 20-h journey. Serum NEFA concentration was greater (P = 0.03) in RS5 and RS10 calves at arrival compared with CON and RS15 calves, but those differences were no longer observed (P = 0.49) 48 h after transportation. Concentration of substance P did not differ (P = 0.18) between treatments, and haptoglobin concentration tended to be greater (P = 0.07) in CON calves compared with the other treatments 48 h after arrival. Hair cortisol tended (P = 0.10) to be lower in RS5 calves compared with the other treatments. The results of this study indicate that rest stop periods ≥ 10 h did not prevent short- and longterm stress after transport in weaned calves.