Dietary protein requirement for tambaqui cultivated in biofloc and clear water systems
Raphael Brito dos Santos, Judá Izel‐Silva, Paulo Adelino de Medeiros, Michelle Midori Sena Fugimura, Thiago Mendes de Freitas, Eduardo Akifumi Ono, Gustavo da Silva Claudiano, Elizabeth Gusmão Affonso
Abstract
This study aimed to compare tambaqui ( Colossoma macropomum ) juvenile (9.20 ± 0.23 27 g) growth performance, digestive enzymes, and body composition when offered different feed crude protein (CP) levels (24, 28, and 32% CP) in biofloc (BFT) vs. clear water (CW) systems over 60 days in a 2 × 3 factorial experimental design. Water quality was also measured throughout the experiment. Decreased nitrite ( P < 0.05) and increased pH, electrical conductivity, nitrate, turbidity, settleable solids, and total suspended solids were observed in the BFT system compared to the CW system ( P < 0.05). Tambaqui in the BFT system presented better feed conversion, final weight, weight gain, productivity, specific growth rate, and protein efficiency rates ( P < 0.05) and 100% survival for all CP treatments and rearing systems. No differences ( P > 0.05) were detected in tambaqui proximal composition and digestive enzymes, except for trypsin, which was higher activity ( P < 0.05) in fish reared in the BFT system. No statistical differences concerning performance indices were noted for CP levels, regardless of the rearing system, although the results suggest better tambaqui adaptive capacity in the BFT system, through better use of the natural food produced in this system. This study indicates that feed containing 24% CP may be offered to tambaqui in both systems, although the BTF was more efficient for rearing tambaqui presenting productivity of 3.09 ± 0.21 kg.m −3 compared to 2.18 ± 0.08 kg.m −3 of the CW system.