In the past few years, shrimp culture has constantly evolved into more intensive production to meet the rising demand for animal protein. However, intensification has introduced a variety of challenges, including the occurrence of disease outbreaks. One such disease that continues to cause profound impact on the farmed shrimp sector globally is vibriosis, cause d by bacterial species, such as Vibrio campbellii, V. harveyi and V. parahaemolyticus . To control vibriosis in farmed shrimp like Penaeus vannamei, there has been a continuous effort in developing more effective antimicrobial strategies as an alternative to antibiotics. In this study, we evaluated the potential of a protected sodium butyrate (PSB) in controlling vibriosis in shrimp. We used g erm-free brine shrimp Artemia nauplii and V. campbellii as a host-pathogen model organism.
In this experiment, 5 treatments with differ ent inclusion levels of PSB (0.5, 1 , 2 , 4, and 8 g/L of PSB) were used. PSB was provided by Novation SL 2002 (Spain) with 54% sodium butyrate protected by a physical and chemical matrix of buffer salts. Germ-free Artemia nauplii were obtained following decapsulation and hatching. G roups of 25 nauplii were transferred to sterile glass tubes that contained 25 ml of sterile artificial seawater. The tubes were added with PSB in different doses, and simultaneously inoculated with the V. campbellii pathogen at 107 cells/ml. T he Artemia therein were also fed with autoclave LVS3. After feeding and the addition of PSB , the glass tubes were incubated. The survival of Artemia were scored 2 days after the addition of the pathogen. As control groups, untreated larvae that were not challenged with V. campbellii (negative control) or challenged (positive control) were used.
Results showed that PSB caused a significant effect on the survival of Artemia challenged with V. campbellii. The nauplii that were exposed to PSB at a dose of 8 g/L had a maximum survival of over 70%, whereas the positive control recorded survivals of around 18%.
To ensure the reproducibility of the results, we repeated the challenge test using the most effective doses. Reproducibility tests showed that the higher dose of PSB (8 g/L) exhibited a significantly higher survival of 84.0 % and 88.0 % in the first and second repeats, respectively .
In conclusion, PSB was highly effective in protecting brine shrimp Artemia against pathogenic V. campbellii. Validation trials conduct ed in Brazil using the dose optimized ( 4 and 8 g/Kg ) in Artemia assay i n Penaeus vannamei ha d shown to improve the performance indices and an improvement in the resistance of the shrimp towards nitrite challenge.