LAUSR

Abstract This study was conducted to determine the effects of selenium (Se)-yeast supplementation on the growth, survival, nutrient utilization, plasma lipid profile, economic benefit, and histological alterations of liver and intestine of meagre, Argyrosomus regius, fingerlings (3.20 ± 0.17 g). Four treatments (three replicates each in 100 × 40 × 30 cm aquaria) included a control group (not supplemented with Se) and three groups fed Se-supplemented diets at doses of 1, 2 and 3 mg Se-yeast kg−1 diet for nine weeks. The final estimated Se concentrations were 0.77, 1.51, 2.97 and 3.98 mg Se kg−1 diet. The results indicated that there is a significant polynomial 2nd order regression improvement in growth performance with a strong correlation coefficient with increasing dietary Se concentrations. The estimated curves beak of WG and SGR values ranged between 4.15 and 3.62 mg Se kg−1, respectively. The survival (%), feed intake, feed and nutrient utilization and whole-body protein content increased significantly with the highest two Se doses (2.97 and 3.98 mg Se kg−1 diet). There was a significant increase in muscle Se accumulation with dietary Se supplementation in a linear dose-dependent manner. The total lipids, cholesterol and low-density lipoprotein cholesterol decreased significantly with increasing dietary Se levels. Moreover, the liver histological investigation showed an improvement in liver histostructure and the absence of pathological signs at high Se levels. Intestinal sections revealed an increase in the area of absorption in the Se-yeast-supplemented groups. The economic evaluation of feed cost kg−1 gain and kg−1protein production decreased with increasing Se-yeast supplementation levels, reaching a 41.63 and 39.57% cost reduction, respectively, with a 3 mg Se-yeast supplementation kg−1 diet. Dietary Se at a dose of 3.98 mg Se kg−1 diet (3 mg Se-yeast) is recommended to improve growth performance, feed utilization, liver and kidney histology, and the economic benefit of meagre juveniles. Additionally, the estimated Se requirement of meagre is around 4 mg kg−1 diet according to the polynomial 2nd order regression.