Effects of dietary organic and inorganic selenium on the growth, selenium concentration and meat quality of juvenile grouper Epinephelus malabaricus

•Requirements of Se based on organic and inorganic Se were 0.98 and 0.90 mg Se/kg-diet.•Dietary Se supplementation enhanced meat quality of grouper.•Muscle Se level was higher in fish fed organic Se than that in fish fed inorganic form.

The aim of this study was to investigate the effects of dietary organic and inorganic selenium (Se) on the growth, Se concentration and meat quality of juvenile grouper, Epinephelus malabaricus. Organic Se (selenomethionine, SeMet) and inorganic Se (sodium selenite, Na2SeO3) were each added to the basal diet of juvenile grouper at 0.3, 0.7, 1.0 and 1.5 mg Se/kg-diet. The basal diet, without Se supplementation, was used as a control. There was a total of 9 experimental diets, and each was fed in triplicate to groups of fish (initial wt: 24.45 ± 0.73 g) in a seawater recirculating system for 8 weeks. Weight gain was significantly (P < 0.05) affected by the dietary Se supplementation levels. The required amounts of Se that were determined from a second-order polynomial regression model were 0.98 (SeMet) and 0.90 mg Se/kg-diet (Na2SeO3). In both the SeMet- and Na2SeO3-supplemented groups, the cutting force and the gel strength of the muscle were higher in fish that were fed with the ≥ 0.3 mg Se/kg-diet than those of fish that were fed with the control diet. The water-holding capacity of muscle was higher in fish that were fed diets with ≥ 0.7 mg Se/kg-diet than that of fish that were fed diets with ≤ 0.3 mg Se/kg-diet. The muscle Se concentration increased linearly with the increase in the dietary Se supplementation level in both the SeMet (Y = 0.45X − 0.09, R2 = 0.93) and Na2SeO3 (Y = 0.12X + 0.03, R2 = 0.95) groups. The results indicate that both SeMet and Na2SeO3 supplementation enhance the meat quality of groupers. The results also suggest that for this species, muscle Se retention is higher in fish that were fed organic Se than that in fish that were fed the inorganic form.