J Aquat Anim Health. 2023 Dec 4. doi: 10.1002/aah.10212. Online ahead of print.
ABSTRACT
Feed additives have attracted increased attention in aquaculture due to their ability to modulate fish gut microbiota, resulting in improved fish growth and immunity. This study assessed two synbiotics’ effects in Japanese eels: Bacillus subtilis with mannooligosaccharide (MOS) and Enterococcus faecium with fructooligosaccharide (FOS). Six diets, including a control (CON), oxytetracycline (OTC), and four synbiotic diets – B.subtilis at 1 × 106 and 107 CFU/g with 5 g/kg MOS (BS6MO and BS7MO) and E. faecium at 1 × 106 and 107 CFU/g with 5 g/kg FOS (EF6FO and EF7FO) – were fed to triplicate groups of 20 fish averaging 6.00 ± 0.07g for eight weeks. Fish fed the BSMOS diets showed significantly higher weight gain (WG), specific growth rate (SGR), and feed efficiency (FE) compared to the CON and OTC diets (P < 0.05), but not significantly different from those fed the EFFOS diets. Weight gain, SGR of fish fed EFFOS were not significantly different from those fed all other diets (P > 0.05). Fish fed the OTC diet showed a higher mean aspartate aminotransferase (AST) level, though the difference was not statistically significant. The myeloperoxidase (MPO) activity of fish fed the BS7MO diet was significantly higher than in all other diets, and the superoxide dismutase (SOD) activity of fish fed the BS7MO diet was also significantly higher than in the EF7FO diet. Overall, the BSMOS synbiotic diets were significantly more effective than the CON diet in enhancing fish survival against Vibrio anguillarum. Our findings suggest that synbiotics can be a preferable alternative to antibiotics in aquaculture.
PMID:38050651 | DOI:10.1002/aah.10212
