EFFICACY OF Biotronic® PX TOP3 ON PERFORMANCE AND RESISTANCE OF NILE TILAPIA Oreochromis niloticus FROM INFECTION BY Aeromonas hydrophila
Disease outbreaks are a major problem for aquaculture production and trade, as they cause economic losses for the production and trade of goods worldwide. Bacterial diseases, especially those caused by Gram-negative bacteria, are contained using disinfectants and antibiotics. However, the use of disinfectants and antimicrobials has shown limited success in preventing or curing aquatic diseases. In addition to this, the awareness to the emergence of resistant pathogens has increased. Therefore, more environmental-friendly preventive alternatives have been investigated in the last years. Organic acids and blends of such acids have been accepted as an efficient tool to prevent and control disease proliferation in aquaculture. In this study the efficacy and the benefits of a commercially available calcium formate based product (Biotronic® PX Top3, BIOMIN, Austria) were investigated on growth performance and disease prevention in Nile tilapia (Oreochromis niloticus) challenged with Aeromonas hydrophila.
The experiment was conducted in 12 tanks (340 L) containing 40 pathogenic free Oreochromis niloticus each, in 4 replicates per treatment. The control group received a standard commercial feed, the experimental group 1 and 2 received the same feed supplemented with Biotronic® PX Top3 at an inclusion rate of 0.5 g/kg and 1 g/kg of feed. Growth parameters were recorded at week 4 and week 8 of the experiment. After 8 weeks 20 fish per tank were randomly chosen, transferred to 80 L tanks, starved for 24 hours, and then challenged by intraperitoneal injection with 7.5x105 CFU Aeromonas hydrophila per fish. Mortality was recorded daily. The challenge experiment was terminated 20 days after infection. Results are summarized in Table 1.
Statistical analysis indicated the differences in weight and FCR as statistically not significant. Differences in mortality on the contrary were found to be statistically significant for the experimental group 1 compared to control. Biotronic® PX Top3 used as feed additive for Nile tilapia resulted in higher average final weight and lower FCR. Biotronic® PX Top3 was found to significantly prevent the fish to succumb to bacterial infection.
The results obtained in this experiment clearly demonstrate that Biotronic® PX Top3 can be taken into consideration as preventive alternative to an extensive use of antibiotics, which contributes to the rise of antibiotic resistance in bacteria.