Abstract The aim of this study was to evaluate the body yield and quality of fresh and post-freezing filet of male and female fish of inbred and non-inbred AquaAmérica genetic group and the hybrid between the AquaAmérica and Tilamax varieties. Forty fish (20 males and 20 females) of each genetic group were housed in four 48-m3 hapa net cages, getting 120 fish per cage. The fish were housed at 51 days of age and farmed for 269 days. Pre-slaughter weight was higher (P<0.05) in the AquaAmérica × Tilamax males (0.805±0.204 kg) than in the inbred AquaAmérica male (0.643±0.115 kg). Filet yield percentage was higher (P<0.05) in the AquaAmérica × Tilamax males (32.14±4.72%) than in the inbred AquaAmérica (28.15±2.67%) and non-inbred AquaAmérica (29.06±2.80%) males. Head and viscera yield percentages, pH, color values (L*, a* and b*), shear force, drip loss and cooking loss did not differ significantly between the genetic groups and sexes. Alterations in meat quality were observed after freezing. In conclusion, inbreeding in the AquaAmérica variety resulted in reduced slaughter weight for males; AquaAmérica × Tilamax males have a higher filet yield; and filet quality is not influenced by crossing, inbreeding, or sex, but is changed after freezing.

Abstract The objective of this unprecedented research was to evaluate performance traits, carcass yield, meat quality, and hematological parameters of pintado amazônico fish (Pseudoplatystoma reticulatum × Leiarius marmoratus) fed diets containing ractopamine (20 mg kg-1) for different periods, during the final growth phase. The following treatments were evaluated: 45 days without ractopamine supplementation (control diet); 30 days of control diet, followed by 15 days of ractopamine supplementation; 15 days of control diet, followed by 30 days of ractopamine supplementation; and 45 days of ractopamine supplementation. Performance traits, carcass yield and hematological parameters were not significantly influenced by the ractopamine supplementation periods. The pH, L* color and a* color parameters of the filet post-slaughter and the L* color of the filet post-thawing were significantly influenced by the period of supplementation with the additive in the diet. Cooking loss was significantly lower in the fillet of fish that received ractopamine. Ractopamine supplementation at the level of 20 mg kg-1 in the diet of pintado amazônico for 15, 30, or 45 days does not alter their production performance, carcass yield, or hematological parameters, but changes the qualitative traits of their filet.