Uso de probiótico multi-espécies durante aeromonose em Colossoma macropomum em sistema de bioflocos: DL50 e mortalidade

Abstract

In Brazil, Colossoma macropomum stands out as the main native species, showing positive results in aquaculture, making it necessary to search for optimization of the production process. For this, products called probiotics are used, aiming to improve immune resistance, intensifying growth and a consequent gain in production. This work aimed to evaluate the effects of the use of multispecies probiotic in tambaqui during aeromonosis using two systems: clear water and biofloc. First, the animals underwent a period of acclimatization and were later placed in polyethylene tanks with a useful volume of 300 ml of water. A total of 192 fish were used, divided into 4 rearing treatments (n=10), as follows: G1 – tambaqui in biofloc control/without probiotic system (BFT-CTL); G2 – tambaqui in biofloc + probiotic system in water (BFT-PA); G3 – tambaqui in biofloc system + probiotic in the diet (BFT-PR); G4 – tambaqui in biofloc system + probiotic in water and feed (BFT-PRA); G5 – tambaqui in a control/no probiotic water recirculation system (SRA-CTL). The Aeromonas hydrophila strain used was isolated from naturally infected fish that were necropsied and brain, kidney and blood fragments were aseptically collected for bacteriological culture. To evaluate the effectiveness of multistrain probiotic supplementation and their effect on production systems, 56 juvenile tambaqui C. macropomum, SRA (326.27 ± 19.38) and BFT (179.44 ± 27.15) were used. The animals were divided into two groups in a completely randomized design (DIC), one of them received 0.5 mL of 0.65% sterile saline solution (control group) and the other received 100 microliters CFU/mL corresponding to LD50% of the same vehicle. and volume. From 48 hours after inoculation via coelomic of A. hydrophila, petechiae and suffusions were evidenced, evolving to cutaneous ulcerations and lethargy in tambaquis. The biofloc system was less efficient than the Água clara system in relation to the survival of juvenile tambaqui challenged with Aeromonas hydrophila. It was verified that the G4 group – tambaqui in biofloc system + probiotic in water and in the feed (BFT-PRA), presented the lowest mortality in relation to the other fish raised in BFT. In the present study, supplementation only with water or feed was not efficient to increase the animals' immunity against a bacterial infection. Keywords: