Effects of feeding prebiotic-enriched Artemia nauplii on growth performance, selected non-specific immune parameters, and survival of zebrafish (Danio rerio) larvae

This study aimed to investigate the effects of feeding zebrafish (Danio rerio) larvae with Artemia nauplii enriched with different levels of prebiotic Prodi 450, containing mannan-oligosaccharide and β-glucan, on growth performance and innate immune parameters. The experiment was conducted in two phases, including Artemia nauplii enrichment and zebrafish larval feeding for 14 days. Artemia nauplii were enriched with four levels of prebiotic including zero (P0), 50 (P50), 100 (P100), and 200 (P200) mg L⁻¹. Larvae with an initial mean weight of 46.08 ± 0.58 mg were reared under controlled conditions. Growth parameters including weight gain, body weight increase, specific growth rate, daily growth rate, feed efficiency, and survival rate were measured, and innate immune parameters including total protein, total immunoglobulin, and alkaline phosphatase activity were evaluated. The results showed that feeding larvae with prebiotic-enriched Artemia nauplii had no significant effect on final weight or survival rate (p>0.05); however, weight gain, daily growth rate, and feed efficiency in the P200 group were significantly higher than in P50 (p<0.05), although not significantly different from the other treatments (p>0.05). Specific growth rate and body weight increase were significantly higher in P0 and P200 compared to P50 (p<0.05), while innate immune parameters showed no significant differences among treatments (p>0.05). These findings suggest that prebiotics may enhance larval growth performance, possibly through regulation of gut microbiota and improving nutrient absorption, even within a short feeding period, whereas their effects on immune indices remain limited at the larval stage. Partial retention of prebiotics within Artemia tissues, as well as enrichment dose and duration, may influence final bioavailability. The nonlinear growth response may reflect complex metabolic and microbial interactions, suggesting the need for further research in this field.