Effect of duration of transport on indicators of stress in lambs

Abstract

Recommendations for the transportation of lambs from a European Commission, which required rest stops of 6 or 24 h, every 8 h, were evaluated for efficacy of reducing stress indicators using Rambouillet x Suffolk lambs (17.6 ± 0.5 kg). The lambs were randomly assigned to one of three groups: 1) transported for 22 h (Continuous; n = 15); 2) transported for 8 h, unloaded and rested for 6 h, transported for 8 h, unloaded and rested for 24 h, transported for 6 h (Rested, n = 15); and 3) Control, which remained in home pasture throughout the study (n = 16). The rest stops were off-trailer; a different pen was used for each; and, a limited amount of grain and ad lib hay and water were provided. Mean temperature in the trailer during the study was 28.4° C with a range of 18.2° C to 39.6° C. Food deprivation in the Continuous lambs was reflected by a decrease in plasma glucose (P < 0.001) and an increase in blood urea nitrogen (P < 0.001), creatinine (P < 0.02) and total bilirubin (P < 0.001) relative to the Rested or the Control lambs. Electrolytes varied within and between all three treatments (P < 0.05), but no distinct pattern indicating dehydration was evident. Serum concentrations of cortisol were greater (P < 0.05) in Continuous lambs than in the Control lambs at 14 h and both the Continuous and Rested lambs had higher concentrations of cortisol (P < 0.05) compared to the Control lambs at 22 h. Plasma IgG antibody response to ovalbumin was suppressed (P < 0.05) in the Continuous and Rested lambs compared to the Control lambs. Lambs in both transported treatments ate grain immediately upon release into the rest pens and drinking occurred following the food consumption. The Continuous lambs lost a greater (P < 0.05) amount of initial BW at the conclusion of transport compared to the Rested lambs and had a lower BW (P < 0.05) than the Rested and Control lambs 8 d after the start of transport. Rest stops improved welfare by reducing physical stress of food deprivation and eliminating BW loss during transport. However, rest stops failed to completely alleviate immunosuppression and 52 h were required to complete the otherwise 22 h long trip. The additional costs of providing the benefits of the rest stops should be examined before these regulations are widely implemented.