Enhancing Growth and Modulation of Gut Microbiota in Red Hybrid Tilapia (Oreochromis sp.) with Host-Associated Leuconostoc lactis as Feed Additive

Economic sustainability and the emergence of infectious diseases remain critical challenges in tilapia aquaculture. Lactic acid bacteria (LAB) are well-known feed additives with probiotic effects in improving overall performance of livestock. This study evaluated the effects of host-associated probiotic, Leuconostoc lactis TARicum AI2, on growth performance, antioxidant, immune responses, and gut microbiota of red hybrid tilapia (Oreochromis sp.) by conducting an 86-day feeding trial. The probiotic, previously characterised for its beneficial traits, was coated on commercial feed at a concentration of 109 CFU g-1. Results showed tilapia fed with probiotic had significant improvement in feed conversion ratio (FCR) and protein efficiency ratio (PER) compared to the control group. Upregulation of cytokine expressions was observed in the probiotic group. Gut microbiota analysis revealed an increased abundance of the genera Clostridium and Leuconostoc in the probiotic-fed tilapia. Beta-diversity indices proved exclusive groups of bacteria present in specific diet only. In conclusion, L. lactis strain TARicum AI2 is a potential probiotic candidate in promoting growth in tilapia as the results suggested it could improve FCR and PER. Feed with lower FCR and higher PER could help tilapia farmers in reducing feed cost, which accounted for the major portion of their production cost. This further enables them to achieve cost-effective, enhanced productivity and economic sustainability in a long run.