Effects of Pelleted and Extruded Feed on Growth Performance, Intestinal Histology and Microbiota of Juvenile Red Swamp Crayfish (Procambarus clarkii)

SIMPLE SUMMARY: Feed processing techniques play a vital role in aquaculture since it is important to apply the appropriate processing technique to maximize production efficiency at the lowest possible cost. In this study, two diets (pelleted and extruded feed) were formulated to fed juvenile crayfish for eight weeks. Results revealed better growth performance by feeding the extruded feed. Furthermore, feeding extruded feed also enhanced the richness of gut microbiota and reduced the proportion of harmful microbial taxa, which showed the beneficial application value of extruded feed in Procambarus clarkii aquaculture. ABSTRACT: The study was conducted to evaluate the extruded and pelleting feed production on growth performance, intestinal histology and microbiome analysis of juvenile red swamp crayfish, Procambarus clarkii. Crayfish were fed either pelleted or extruded feeds that were made using the same formula. Crayfish fed extruded feed had a lower feed conversion ratio, as well as significantly higher levels of trypsin and amylase (p < 0.05) than those fed pelleted feed. However, other growth indices and the activity of lipase were not significantly influenced by the feed processing technique (p > 0.05). In comparison with the pelleted feed group, the lamina propria thickness of crayfish fed extruded feed was significantly lower (p < 0.05). Additionally, the abundance of intestinal microbiota in the extruded feed group was higher than that in the pelleted feed group. The dominant phyla in the intestine of both groups were Proteobacteria, Tenericutes, and Firmicutes, and the relative abundance of Proteobacteria in the extruded feed group was significantly higher than that in the pelleted feed group (p < 0.05). These results revealed that P. clarkii fed extruded feed had higher feed utilization and better intestinal health.