FLESH QUALITY AND STRESS RESPONSES OF Piaractus mesopotamicus AFTER EXPOSURE TO SUBLETHAL LEVELS OF AMMONIA AND SUBSEQUENT RECOVERY

This study aimed to evaluate de effect of the exposure to sub-lethal levels of ammonia on blood parameters and flesh quality of juvenile pacu (Piaractus mesopotamicus), including assessment of such parameters post recovery in ammonia-free water. Juveniles (27.1 +/- 5.4 g) were exposed to concentrations of ammonia at 0.0 (control); 0.5; and 1.0 mg N-NH3 L-1 for 10 days followed by the same period of recovery in ammonia-free water. On the 10th day post exposure and after a recovery period, samples of blood were taken for glucose, lactate analyses and evaluation of haematocrit. To evaluate lipid peroxidation, proximate composition and sensory analysis, samples of muscle/fillets were also obtained. Exposure to ammonia caused alterations in haematological response and negatively affected sensory analysis of pacu fillet. However, proximate composition was unchanged and lipid peroxidation process was not intensified in muscle. In conclusion, exposure to sublethal levels of ammonia induces secondary stress responses and altered the organoleptic characteristics of pacu flesh. Nevertheless, a recovery period of 10 days was sufficient to allow for a complete restoration of the homeostasis and organoleptic characteristics of the fillet.