Comparative analysis of oxidized fish oil and coenzyme Q10 on the intestinal microecology of largemouth bass Micropterus salmoides at different growth stages

Coenzyme Q10 (CoQ10) is a powerful antioxidant that is gradually being used in aquafeeds. Here, we examined the influence of oxidized fish oil and CoQ10 supplementation on intestinal microbiota of Micropterus salmoides at different growth stages. Three isonitrogenous and isoenergetic diets were formulated to contain 100% fresh fish oil (FFO), 100% oxidized fish oil (OFO) and OFO + 0.1% CoQ10 (QFO) and were fed to Micropterus salmoides (95 ± 0.60 g) for 70 days. Furthermore, three different growth stages (28-day, 49-day, 70-day) were selected to observe the dynamic changes of intestinal microbiota. The growth performance of fish fed QFO were significantly higher than that of fish fed OFO after a 70-day’s feeding. Intestinal microbial community of Micropterus salmoides was significantly affected by different growth stages more than diets. The abundance of phylum Proteobacteria showed an increasing trend, while the abundance of Firmicutes decreased with increased feeding time. Compared with OFO, diet supplemented with CoQ10 significantly increased the abundance of Firmicutes, and decreased Proteobacteria on the 28- and 70-day of feeding. When fish fed OFO and QFO, Simpson and Shannon indices significantly increased with increased feeding time from 28 to 70 days. Fish fed QFO significantly decreased the value of Bray-Curtis distance than those fed FFO on the 70-day of feeding. Moreover, Bray-Curtis distance showed an increased trend with increased feeding time. Notably, intestinal microbial functional prediction indicated that OFO suppressed amino acid metabolism, while long-term oral administration of CoQ10 could improve amino acid metabolism and detoxification of Micropterus salmoides. This study demonstrated that prolonged application of CoQ10 is needed to produce some beneficial effects to Micropterus salmoides.