Unlocking the potential of enzymatically hydrolyzed corn gluten meal for improving growth, intestinal health, and stress resistance in juvenile Chinese mitten crab (Eriocheir sinensis)

Enzymatically hydrolyzed corn gluten meal (ECGM), characterized by its low molecular weight, improved digestibility, and antioxidant properties, shows great potential as a functional feed additive in aquaculture. This study assessed how ECGM supplementation in 15 %-fishmeal diets affected the growth and health of juvenile Eriocheir sinensis. The experiment was conducted by feeding juvenile Eriocheir sinensis diets containing 0, 10.0, 20.0, 30.0, 40.0, and 50.0 g/kg of ECGM (designated as ECGM0 to ECGM5) for 8 weeks. Compared with ECGM0 group, the ECGM2-ECGM4 groups presented significantly more weight gain, molting frequency, and digestive enzyme activities (trypsin, lipase, and amylase) (P < 0.05) and greater whole-body crude protein and lipid deposition. These effects might be associated with the upregulation of genes related to the mechanistic target of rapamycin signaling pathway, with significantly elevated expression of mtor, s6k1 and s6 in the ECGM3–5 groups (P < 0.05). In addition, ECGM3 supplementation increased the α diversity of the intestinal microbiota, increased the abundance of Firmicutes, reduced the abundance of Actinobacteria, and enriched the probiotic genus Dysgonomonas. Under 72-hour acute heat stress (35 °C), ECGM-fed crabs presented reduced expression of heat shock proteins (hsp70, hsp90) and increased expression of antioxidant-related genes (gsh-px, gst, cu-znsod, cat) (P < 0.05). Furthermore, following 24 h of lipopolysaccharide challenge, ECGM significantly upregulated the expression of antilipopolysaccharide factors (alf1, alf2, alf3) and downregulated the expression of inflammatory mediators (tlr and relish) (P < 0.05). These findings demonstrate that ECGM functions as both a growth promoter and health enhancer in Eriocheir sinensis aquaculture.