A multispecies probiotic modulates growth, digestive enzymes, immunity, hepatic antioxidant activity, and disease resistance of Pangasianodon hypophthalmus fingerlings

An eight-week trial was designed by feeding Pangasianodon hypophthalmus fingerlings on diets supplemented with a multispecies probiotic comprised of three probiotic bacteria (Bacillus subtilis, Lactobacillus plantarum, and Enterococcus faecium) in combination with a probiotic yeast (Saccharomyces cerevisiae). The effects were observed regarding growth, body composition, digestive enzymes, liver function enzymes, serum metabolites, immunological responses, hepatic antioxidant capacity, and resistance to the challenge with Aeromonas hydrophila. Fish (9.54 ± 0.50 g) were allocated into four triplicate groups and were fed on formulated pelleted diets enriched with varying levels of the probiotic as 0.0 (reference or CONT), 0.5, 1.0, and 1.5 g per 1 kg feed. After the feeding trial ended, a significant augmentation of the growth performance in terms of the fish's final weight, weight gain and specific growth rate were observed in the probiotic-enriched groups in comparison to the CONT group. There were also improvements in the feed intake and feed conversion ratio. Nevertheless, no variations were noticed in whole-body analysis, liver enzymes (AST, ALT, and ALP), and serum metabolites (blood urea nitrogen, uric acid, and creatinine) among the experimental groups. Meanwhile, digestive enzymes (lipase, amylase, and protease) and enzymatic antioxidant activities (CAT, SOD, and GPx) were increased in all probiotic-supplied groups in comparison with the CONT group. On the other side, hepatic malondialdehyde concentrations declined in probiotic-supplemented groups in relation to the CONT group. An improved immunological response (serum lysozyme activity and total immunoglobulins) was aligned with the higher cumulative survival of P. hypophthalmus in response to the pathogenic A. hydrophila challenge. Taken together, the enhancement of the growth, antioxidant activity, and immunity, aligned with increased resistance to A. hydrophila, can suggest the potentiality of dietary supplementation with a multispecies probiotic composed of probiotic bacteria and yeast to improve the functionality and effectuality of aquadiets prepared for this valuable fish species.