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

Yun Xia; Miao Wang; Fengying Gao; Maixin Lu; Gang Chen

doi:10.1016/j.aninu.2019.07.002

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

Anim Nutr. 2020 Mar;6(1):69-79. doi: 10.1016/j.aninu.2019.07.002. Epub 2019 Aug 23.

Authors

Yun Xia¹, Miao Wang¹, Fengying Gao¹, Maixin Lu¹, Gang Chen²

Affiliations

¹ Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China.
² College of Fisheries, Guangdong Ocean University, Zhanjiang 524025, China.

Abstract

This study investigated the effects of the Streptococcus agalactiae antagonizing probiotics Bacillus cereus NY5 and Bacillus subtilis as feed additives for Nile tilapia in terms of growth performance, intestinal health and resistance to S. agalactiae. 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 B. subtilis (1 × 10⁸ CFU/g feed, BS group), B. cereus NY5 (1 × 10⁸ CFU/g feed, BC group), and B. subtilis + B. cereus NY5 (0.5 × 10⁸ 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 S. agalactiae resistance in Nile tilapia (P < 0.05). Gut microvilli length and density and c-type lysozyme (lyzc) gene expression were significantly increased by probiotic supplementation (P < 0.05). The results of high-throughput sequencing showed that the B. cereus NY5 and B. subtilis + B. cereus 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, B. cereus NY5 and the mixture of B. subtilis and B. cereus NY5 at 1 × 10⁸ 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.

Keywords: Bacillus cereus; Bacillus subtilis; Intestinal microbiota; Probiotic; Tilapia.