PSXIII-2 Effect of Rest, Post-Rest Transport Duration, and Conditioning on Performance and Physiological Welfare Indicators of Beef Calves

The aim of this study was to assess the effects of conditioning, rest, and post-rest transport duration on welfare indicators of 6-7 mo old beef calves. A total of 328 weaned calves (237 ± 29.7 kg BW) were randomly assigned to a 2 × 2 × 2 factorial design: conditioning, conditioned (C) or non-conditioned (N); rest, 0 (R0) or 8 (R8) h, and post-rest transport, 4 (T4) or 15 (T15) h. Calves were sampled prior to and after 20h of transport, prior to and after the additional 4 or 15-h transport, and at 1, 2, 3, 5, 14, and 28 d after transport ended. Data were analyzed using the GLIMMIX procedure of SAS. Fixed effects were conditioning, transport and time nested within rest period, while random effects were animal and pen. For R0-T4 calves, the mean L-lactate concentrations were greater than R8-T4 calves on d 1 and 2 (p-values = 0.02) while, for R0 calves, mean ADG was greater than R8 calves 14 to 28 d after transport (p-values < 0.01). For R8-T4 calves 1 week after transport, mean ADG was greater and mean WBC counts were less than R8-T15 calves on d 5 (p-values < 0.01). For N calves, overall mean haptoglobin, creatine kinase, serum amyloid-A, and non-esterified fatty acids were greater than C calves (p-values ≤ 0.05). Overall, few and inconsistent differences were observed for rest, where rest improved L-lactate but affected ADG. Few differences were observed for transport, where shorter transport durations after the rest improved ADG and WBC counts. In general, N calves had greater physiological indicators of reduced welfare than C calves. Based on these findings, the best way to improve calf welfare during and after transport is to condition them prior to transport.