Evaluating the effects of lauric acid supplementation on growth, digestive enzymes, immunity, reproduction, and gene expression in Zebrafish

This study investigates the dose-dependent effects of dietary lauric acid (LA) supplementation on growth, digestion, immunity, reproduction and hepatic function in zebrafish ( Danio rerio ). Four diets containing 0.0 % (Control), 0.05 %, 0.1 %, and 0.2 % LA were fed to zebrafish with an average of 0.22 ± 0.01 for eight weeks. Results demonstrated that the Inclusion of 0.05–0.1 % LA significantly enhanced zebrafish growth performance and digestive enzyme activities ( p < 0.05). Lauric acid supplementation at 0.05 % and 0.1 % levels significantly reduced liver enzymes ALP and AST; ALT decreased significantly only at 0.1 % ( p < 0.05). Gonad weight, ovum number, GSI, absolute and relative fecundity significantly increased in LA-fed groups compared to the Control ( p < 0.05). Serum total protein and total immunoglobulin (Ig) content significantly increased in LA-fed groups compared to controls ( p < 0.05). Mucus total protein and total immunoglobulin (Ig) content increased notably in dietary 0.05 % and 0.1 % LA fed groups relative to the control ( p < 0.05). Significant upregulation was observed for growth-related genes; growth hormone ( GH ) and insulin-like growth factor 1 ( IGF-1 ); immune-related genes; interleukin-1 beta ( IL-1β ) and tumour necrosis factor alpha ( TNFα ); and reproduction-related genes; vitellogenin ( Vtg ) and estrogen receptor ( EsRα ) in the 0.05 % and 0.1 % LA groups ( p < 0.05). Overall, lauric acid has proven to be a practical feed additive for zebrafish, with inclusion levels of 0.05–0.1 % providing optimal biological benefits. Once confirmed in other aquatic species, it may serve as a promising candidate for future applications in sustainable aquaculture nutrition. • Inclusion of 0.05 % LA significantly enhanced zebrafish growth performance ( p < 0.05). • Gonad weight, ovum number, GSI, absolute and relative fecundity significantly increased in LA fed groups compared to control (p < 0.05). • Serum total protein and total immunoglobulin content significantly increased in LA fed groups relative to the control (p < 0.05). • Mucus total protein and total immunoglobulin content significantly increased in dietary 0.05 % and 0.1 % LA fed groups compared to control (p < 0.05). • Growth (GH, IGF-1), immune (TNF, IL-1β) and reproduction- related (vtg and ESR) were significantly upregulated at 0.05 % and 0.1 % LA acid groups (p < 0.05).