Dietary nanoencapsulated A-Ghrelin improves growth performance and health status in juvenile Siberian sturgeon

This study evaluated a novel multi-functional feed supplement for juvenile Siberian sturgeon ( Acipenser baerii ), combining an acetylated ghrelin analog (A-Ghrelin) with a chitosan-alginate-iron oxide (Fe₂O₃) nanoparticle delivery system. Over 60 days, 240 fish (initial weight: 8.5 ± 0.9 g) were assigned to eight diets ( n = 3 tanks/treatment). The complete supplement (nanoencapsulated A-Ghrelin + 1 mg/kg nano-Fe₂O₃) yielded the best outcomes: weight gain increased 75.5% (73.9 vs. 42.1 g in control), feed conversion ratio improved from 4.1 to 1.8, and reduced ALT/AST. Modulation of humoral immune parameters was observed, including increased complement activity and immunoglobulins. The number of intestinal fold and villi density increased by 39.7% and 28.2%, respectively. Gene expression showed upregulation of igf-1 (2.4-fold) in A-Ghrelin group and NpY (7.3-fold) in the Nano Fe + Al-Cs group. The encapsulation system achieved 73.8% efficiency for A-Ghrelin with a pH dependent sustained release profile under simulated gastrointestinal conditions in vitro. This formulation represents a promising precision nutrition strategy for sturgeon aquaculture.