Changes in physiological responses and immunity of blunt snout bream Megalobrama amblycephala from transport stress

This study aimed to investigate the effects of transport stress on the physiological responses and immunity of Megalobrama amblycephala (blunt snout bream) . Fish (109.67 ± 1.51 g) were sampled at nine time points: before transport (control), at 0 h, 1 h, 3 h, 6 h, 12 h, 24 h, 3 days, and 7 days after 4 h of medium-distance transportation, and four fish were sampled in each time point. The results showed that plasma cortisol, triiodothyronine (T 3 ), complement component 3 (C3), complement component 4 (C4), immunoglobulin M (IgM) and nitrogen monoxide (NO) concentrations, and alternative complement pathway (ACH50), acid phosphatase (ACP), and myeloperoxidase (MPO) activities all reached the peak at 0 h after transportation; C4 and NO concentrations as well as ACP and MPO activities returned to the control level after 1 h, ACH50 activity as well as cortisol, T 3, and IgM concentration returned to the control level after 12 h, and C3 concentration returned to the control level after 24 h respectively. Plasma glucose and total protein concentrations as well as lysozyme activity all reached the peak at 1 h after transportation, total protein concentration and lysozyme activity returned to the control level after 3 h, and glucose concentration returned to the control level after 6 h ( P < 0.05). Liver heat shock protein 70 expression reached the peak at 1 h after transportation, and returned to the control level after 24 h; liver heat shock protein 90 expression reached the peak at 0 h after transportation and returned to the control level after 12 h ( P < 0.05). Overall, these findings suggested that 4 h of medium-distance transportation caused stress response of blunt snout bream, and transport stress had a significant effect on plasma indicators. But the recovery of 24 h after transport could return the physiological response, immune indexes, and the expression of heat shock protein to the normal level. This also provided data support for the medium-distance transportation of blunt snout bream in the future.