| dc.description.abstract | Probiotics have become an alternative in the aquaculture industry and are considered an environmentally friendly approach for disease control. However, the maintenance of the viability of probiotic bacterial cells during storage is quite challenging. This study aimed to investigate the potential effects of euryhaline probiotic and paraprobiotic B. cereus BR2 on African catfish, specifically on growth performance, gastrointestinal health, immune- related gene expression, and resistance to Edwardsiella tarda ETS1.1. The test feed was enriched with a 1% (w/w) dose of probiotics and paraprobiotics at a cell density of 108 and 1010 CFU mL-1, each with replications. For the diet supplementation experiment, African catfish fry with an initial average body weight of 6.67±0.34 g were randomly placed into six aquaria containing 60 L of freshwater and reared for 30 days. Afterward, fish were chal- lenged intraperitoneally on day 31st with E. tarda at cell density of 107 CFU mL-1 and reared for 14 days. The results showed that diets treated with probiotics and parapro- biotics 108 and 1010 CFU mL-1 significantly (p < 0.05) increased mean final weight, mean final biomass, specific growth rate (SGR), disease resistance (survival rate), and reduced feed conversion ratio (FCR) values. Digestive enzyme (amylase, protease, lipase) activi- ties were measured higher in supplementation treatments than in control fish. Furthermore, the immune-related genes IL-1ß and MHC-2ß expression significantly upregulated after supplementation. Post-challenge test, IL-1ß showed the highest upregulation in DPI1 and downregulated in DPI 3 and DPI 7, while MHC-2ß showed the opposite expression pat- tern, with the highest expression shown in DPI 7. The supplementation of probiotic and paraprobiotic B. cereus BR2 per oral effectively improved growth performance, digestive enzyme activity, immune-related gene expression, and resistance of African catfish to E. tarda | |
