New insights into the effect of xylooligosaccharide derived from agricultural waste, single or combined dietary supplementation with mixed probiotics on growth, flesh quality, health condition and disease resistance in Nile tilapia (Oreochromis niloticus)

This study aimed to study the effects of single or combined dietary supplementation of xylooligosacharides (XOs), prebiotics derived from agricultural waste and mixed probiotics (Bacillus subtilis TISTR 008 and Lactobacillus plantarum TISTR 1854) on growth performance, flesh quality, health condition and disease resistance in Nile tilapia (Oreochromis niloticus). Fish received four types of diets: a basal diet (control); XOs (prebiotics); a mixture of Bacillus subtilis TISTR 008 and Lactobacillus plantarum TISTR 1854 (probiotics); and a combination of XOs and a probiotic mixture (synbiotics) for 56 days. The results show that dietary prebiotics, probiotics, and synbiotics improved growth performance including final body weight, weight gain, average daily gain, and protein efficiency ratio compared to the control diet. Interestingly, the feed conversion ratio was improved by dietary prebiotics, probiotics, and synbiotics supplementation. Concurrently, innate immunity parameters such as total antioxidant, lysozyme, catalase, and glutathione S transferase were mostly higher in fish fed the prebiotics, probiotics, and synbiotics diets. Moreover, we observed significant increases in digestive enzyme activities, including protease, amylase, and lipase, in fish fed probiotic diets. After the feeding trial, fish were intraperitoneally injected with Streptococcus agalactiae, and the cumulative 14-day mortality rate was calculated. High survival rates were observed in all groups that received supplementation with prebiotics, probiotics, or synbiotics in their feed. This improvement is correlated with an increase in the transcriptional levels of immune- and growth-related factors. Interestingly, this study highlights the use of prebiotics and synbiotics containing XOs to boost the PUFA n-3 and n-6 content in the fish fillets. Our findings indicate that adding XOs as prebiotics to the diet significantly enhances the overall performance of fish when compared to the effects of probiotics and synbiotics. In summary, XOs may have the potential as organic compounds derived from agricultural waste for specific probiotic and synbiotic products in the aquaculture industry when combined in the right proportions.