Effect of dietary hydroxy-selenomethionine supplementation on growth performance, antioxidant status, and gene expression in Nile tilapia (Oreochromis niloticus)

Sammendrag

In this study, the effect of hydroxy-selenomethionine (OH-SeMet) and sodium selenite (Na₂SeO₃) supplementation on growth rates, physiological parameter, and mRNA levels in Nile tilapia (Oreochromis niloticus) was examined. Eleven diets were prepared, consisting of a basal diet devoid of selenium (control) and ten diets supplemented with two selenium sources, OH-SeMet and Na₂SeO₃, each at 0.25, 0.50, 1.0, 1.5, or 2.0 mg Se/kg. Fish with an initial weight of 6.7 ± 0.1 g were fed for 60 days in triplicate groups. Growth indices and feed efficiency were significantly increased in selenium fed groups compared to control group. The fish that were fed OH-SeMet at 0.5 mg Se/kg exhibited enhanced somatic growth and nutrient utilization, feed conversion ratio and protein efficiency ratio. Blood parameters (i.e., hemoglobin, hematocrit, red blood cell, white blood cell) showed marked differences with selenium supplementation and the effect was greater with OH-SeMet than Na₂SeO₃. Serum biochemistry indicated optimized metabolic status, where serum AST (aspartate aminotransferase) and ALT (alanine amino transferase) activities decreased in Se fed groups. While glucose, cholesterol, and triglyceride levels decreased with increasing Se levels, indicating alterations in physiological status. Selenium supplementation enhanced lipase activity with a highest activity observed at 0.5 mg/kg OH-SeMet treatment. Antioxidant enzyme (CAT and GPx) activity elevated in OH-SeMet groups and MDA (malondialdehyde) decreased, suggesting an improved antioxidant status. Selenium bioaccumulation increased with OH-SeMet-fed fish, with liver showing higher accumulation than muscle. Intestinal morphology is indicative of improved villus length, width, and crypt depth in Se fed fish. Gene expression analysis exhibited upregulation of growth-related genes (MyoD, myogenin), and antioxidant genes (Nrf2, CAT, GPx) and downregulation of myostatin with selenium supplemented groups, with optimal expression at 0.5 mg/kg OH-SeMet. Results indicate that 0.5 mg/kg OH-SeMet optimizes somatic growth by integrating enhanced digestive enzyme activity with expanded intestinal absorptive surface area (intestinal morphology) and increased antioxidant enzyme activity compared to inorganic selenium without inducing the hepatic stress markers observed at higher inclusion levels.

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DOI : doi.org/10.1016/j.anifeedsci.2...
NVA : hdl.handle.net/11250/5505505