Effects of dietary probiotic supplementation on the growth, gut health and disease resistance of juvenile Nile tilapia ().

This study investigated the effects of the antagonizing probiotics NY5 and as feed additives for Nile tilapia in terms of growth performance, intestinal health and resistance to . A total of 720 apparently healthy juvenile Nile tilapia (0.20 ± 0.05 g) were randomly divided into 4 equal groups with 3 replicates for each group. Fish were fed a basal diet (control check group, CK group) supplemented with (1 × 10 CFU/g feed, BS group), NY5 (1 × 10 CFU/g feed, BC group), and  +  NY5 (0.5 × 10 CFU/g feed of each probiotic, BS + BC group) for 6 wk, and the probiotic supplementation groups were then fed the basal diet for 1 wk to investigate the gut microbial community. The results of this study showed that BS + BC and BC treatments significantly increased weight gain (WG), feed conversion ratio (FCR) and . resistance in Nile tilapia ( < 0.05). Gut microvilli length and density and c-type lysozyme () gene expression were significantly increased by probiotic supplementation ( < 0.05). The results of high-throughput sequencing showed that the NY5 and  +  NY5-supplemented feed resulted in a significant improvement in tilapia autochthonous gut bacterial communities and had a stimulation effect on a variety of potential probiotics after 6 wk of feeding. After cessation of probiotic administration for 1 wk, the gut bacteria of the fish in the BS + BC and BC groups had minor changes and maintained a stable state. Consequently, it was inferred that, as a feed supplement, NY5 and the mixture of and NY5 at 1 × 10 CFU/g feed were able to promote growth and disease resistance, which may be associated with the supplement's effects on gut immune status, intestinal morphology, and intestinal microbial community composition.