Feed withdrawal of broilers before transport changes plasma hormone and metabolite concentrations

Two experiments were completed to observe the combined effects of feed withdrawal and the catching and transport process on stress and energy metabolism. During one experiment 192 male broilers (46 d of age) were used, and in the other we used 240 male broilers (49 d of age). The experiments consisted of 2 interventions: feed intervention and transport intervention. The feed intervention took 10 h, in which broilers had full access to feed or feed was withdrawn and, thereafter, had a transport intervention that took 3 h, in which broilers were caught, crated, loaded, transported, and then had to wait in the crates for 1 h or remained in the pens. After the transport intervention, blood samples were taken to determine plasma corticosterone, triiodothyronine, thyroxine, glucose, lactate, uric acid, nonesterified fatty acid, and triglyceride concentrations. Changes in BW were also assessed. Broilers from which feed was withdrawn before the transport intervention showed higher thyroxine concentration and lower triiodothyronine, triglyceride, glucose, and lactate concentrations compared with broilers that had access to feed before the transport intervention. These findings indicate a negative energy balance and stress. Broilers that were transported after feed withdrawal had BW losses of approximately 0.42% per hour, which is approximately 0.30% per hour more than those that had full access to feed. To continue feeding broilers until catching resulted in higher BW at the slaughterhouse and less stress, as shown by a negative energy balance and might improve meat quality.