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This study assesses the respiratory dynamics related to stress parameters and resting time before slaughter, in the quality of surubim (Pseudopatystoma spp.) fillets. A completely randomized design was conducted using five treatments: resting time before slaughter of 0, 2, 4, 8 and 24 hours, with 15 fish sampled per treatment. Time 0 corresponded to the treatment without resting time, where the fish were slaughtered immediately after arriving at the processing plant. The resting time did not affect the electrolyte balance, hemoglobin, plasma, hepatic glycogen, myofibrillar fragmentation index (MFI) and water holding capacity (WHC) of surubins. However, with increased resting time, there was a significant decrease in muscle glycogen and an increase in blood pH and blood bicarbonate levels. Additionally, respiratory parameters showed an increase in pO2 and, consequently, in O2 saturation and a decrease in pCO2.The hematocrit and MCV values of the surubins after 24 hours of resting decreased significantly. In the first hours of resting, the highest values of erythrocytes and CHCM were observed. The lowest level of stress was observed for fish having 24 hours of resting. Fish having longer resting periods (8 and 24 hours) presented fillets with a higher pH (P |
