Productive performance and physiopathological responses of tambaqui fed with β‑glucan enriched diet

Abstract

The objective of this work was to evaluate the effect of the immunostimulant β‑glucan in tambaqui (Colossoma macropomum) diet on the productive performance, physiological and immunological responses, and the resistance to Aeromonas hydrophila challenge. The experiment was carried out in a completely randomized design in a 5x2 factorial arrangement, with five levels of β‑glucan in the diet (0, 0.1, 0.2, 0.4, and 0.8%) and two sampling times (before and after challenge with A. hydrophila), with three replicates. Fish (28.65±0.49 g; 12.14±0.07 cm) were fed for 60 days with diets (28% crude protein) supplemented with commercial β‑glucan preparation. After the feeding period, the productive performance was evaluated, and fish were challenged with A. hydrophila. Hematological and immunological parameters (concentration and activity of lysozyme) were determined before and after the bacterial challenge. After bacterial challenge, the occurrence of normocytic‑normochromic anemia was observed. β‑glucan supplementation did not change lysozime concentration and activity; however, the lowest concentration of β‑glucan (0.1%) favored higher survival rates for the species when challenged with Aeromonas hydrophila. β‑glucan supplementation does not influence tambaqui productive performance and hematological parameters.