Aquaculture in South America and the Caribbean in recent years has shown growth 7.7% above the world average, with tilapia being the most produced species. In Brazil, the fourth largest producer of tilapia in the world, the production of this species is carried out in part in network tanks, located in large reservoirs. However, this super-intensive production system presents greater health challenges, such as the occurrence of bacterial diseases, which result in significant losses, with high morbidity and mortality rates. To prevent the occurrence of outbreaks of bacterial diseases, vaccination is a common practice, accompanied using antimicrobials before and after this management. The injudicious use of these products can result in several problems, such as bacterial resistance, environmental and fish contamination, and increased labor and production costs. Therefore, the objective of this study was to evaluate the effectiveness of vaccination protocols, with and without the use of antimicrobials during the vaccination management of Nile tilapia, raised in net cages. The experiment was carried out in a commercial fish farm located in the Furnas reservoir, Minas Gerais, Brazil, from January to July 2023. Six hundred male Nile tilapia (21.75 ± 1.06 g) were maintained in six net tanks with a total volume of 6 m³ (2.0 x 2.0 x 1.5 m), arranged in a line and spaced 2.0 m apart. After acclimation, fish were vaccinated intraperitoneally with 0.05 ml of trivalent autogenous vaccine containing Streptococcus agalactiae serotype Ib, Aeromonas hydrophila and Edwardsiella tarda using aluminum hydroxide as an adjuvant. The experimental design was completely randomized, with two treatments (G1 - animals immunized with the trivalent autogenous vaccine and without antimicrobials and G2 - animals vaccinated and with the use of an antimicrobial added to the diet and used five days before and five days after vaccination) with three replicates. The fish were fed three times a day with extruded feed, according to the feeding program provided by the manufacturer. The average water temperature remained within acceptable values for the species (25.11 ± 2.40 °C). At the end of the experiment, all fish were harvested, and the main production parameters were measured (Table 1).
The results of this study did not demonstrate significant differences (p>0.05) in the productive performance of tilapia that received or did not antimicrobials before and after vaccination, concluding that the use of antimicrobials in this period can be eliminated from the vaccination protocol, making the activity more sustainable and with greater food security.