Ractopamine supplementation in the diet of pintado amazônico during the final growth phase

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.

Key words
Beta-adrenergic agonist; Learius marmoratus; nutrition; Pseudoplatystoma reticulatum