|Abstract: ||本研究比較石斑魚稚魚(Epinephelus malabaricus)對有機態之甲硫胺酸硒(selenomethionine)與無機態之亞硒酸鈉(sodium selenite)利用性及對其肉質之影響。甲硫胺酸硒與亞硒酸鈉分別以0.3、0.7、1.5、2.5、5.0及10.0 mg Se/kg等劑量添加於基礎飼料中，硒之實際分析值為 0.37、0.80、1.02、1.49、2.63及6.88 mg Se/kg (甲硫胺酸硒)；與0.30、0.58、0.93、1.72、3.11及7.23 mg Se/kg (亞硒酸鈉)，另以未添加硒為控制組(含0.17 mg Se/kg)，總共13組，分別餵予初重24.45 ± 0.73 g 之石斑魚，每組三重複，於密閉循環系統中飼養八週。結果顯示，以甲硫胺酸硒為硒來源時，餵食0.37、0.80、1.02、1.49及6.88 mg Se/kg 五組，石斑魚之增重率顯著(p<0.05)高於控制組；餵食0.80與1.02 mg Se/kg 兩組肝臟麩胱甘肽過氧化酶(GPx)活性顯著較其他各組高；餵食0.80 mg Se/kg 組魚肉保水力顯著較控制組高。以亞硒酸鈉為硒來源時，餵食飼料0.58與0.93 mg Se/kg兩組之增重率顯著高於其他各組；餵食0.30、0.58、1.72及7.23 mg Se/kg組，麩胱甘肽過氧化酶活性較餵食0.93 mg Se/kg組高；餵食0.58、0.93及1.72 mg Se/kg 三組魚肉保水力較控制組高。飼料中硒的來源不論為甲硫胺酸硒或亞硒酸鈉，石斑魚全魚體、肌肉及肝臟中硒濃度，皆隨飼料中硒的添加劑量增加而上升。石斑魚餵食甲硫胺酸硒0.80、1.49及6.88 mg Se/kg與餵食亞硒酸鈉0.58與1.72 mg Se/kg 五組，經低溫(70C與-200C)儲藏，肌肉脂質過氧化物指標(TBARS)增加較控制組緩慢。全魚體及魚肉硒的蓄積量，均以餵食甲硫胺酸硒高於亞硒酸鈉。以線性迴歸分析全魚體硒保留量及考量魚體之增重率，估得石斑魚稚魚對甲硫胺酸硒與亞硒酸鈉之最適需求分別為0.49-0.80與0.58-0.93 mg Se/kg，顯示石斑魚對甲硫胺酸硒與亞硒酸鈉之利用性相近。本實驗結果亦顯示飼料中不論添加甲硫胺酸硒與亞硒酸鈉，均可提高石斑魚肉質及保存期間肉品安定性。|
The study was to investigate the utilization of organic selenium (selenomethionine, SeMet) and inorganic selenium (sodium selenite, Na2SeO3) by juvenile grouper, Epinephelus malabaricus, and their effects on meat quality. SeMet and Na2SeO3 were each supplemented to the basal diet at 0.3, 0.7, 1.5, 2.5, 5.0 and 10.0 mg Se/kg, providing 0.37、0.80、1.02、1.49、2.63 and 6.88 mg Se/kg diet (SeMet), and 0.20、0.26、0.63、1.72、3.11 and 7.23 mg Se/kg diet (Na2SeO3), respectively. Basal diet without Se supplementation (containing 0.17 mg Se/kg diet) was used as control. There were total 13 experimental diets, each was fed to triplicate groups of fish (initial body weight 24.45 ± 0.73 g) in a seawater recirculated rearing system for 8 weeks. In SeMet supplemented groups, weight gain (WG) of fish fed diets with 0.37, 0.80, 1.02, 1.49 and 6.88 mg Se/kg diet were significantly (P < 0.05) higher than that in fish fed the control diet; hepatic glutathione peroxidase (GPx) activity was higher in fish fed diets with 0.80 and 1.02 mg Se/kg diet than all the other dietary groups; muscle water-holding capacity was higher in fish fed the diet with 0.80 mg Se/kg diet than that in fish fed the control diet. In the Na2SeO3 supplemented groups, WG was higher in fish fed diets with 0.80 and 1.02 mg Se/kg diet than that all the other dietary groups; hepatic GPx activity was higher in fish fed diets with 0.30, 0.58, 1.72 and 7.23 mg Se/kg diet than that in fish fed the diet with 0.93 mg Se/kg; muscle water-holding capacity was higher in fish fed diets with 0.58, 0.93 and 1.72 mg Se/kg diet than that in fish fed the control diet. In both SeMet and Na2SeO3 groups, whole body, muscle and hepatic Se concentrations increased linearly with the increase of dietary Se supplementation level. While grouper muscle stored at 70C or -200C, the thiobarbituric acid-reactive substance (TBARS) value was lower in fish fed diets with 0.80, 1.49 and 6.88 (SeMet as Se source) mg Se/kg diet, and 0.58 and 1.72 (Na2SeO3 as Se source) mg Se/kg diet than that in fish fed the control diet. Analysis of whole-body retention and muscle Se concentration was higher in fish fed diet with Se supplemented from the organic form than those in fish fed diet with Se supplemented from the inorganic form. Linear regression analysis of whole-body Se retention of the fish together with the fish WG indicate that the adequate dietary Se requirements are about 0.49-0.80 and 0.58-0.93 mg Se/kg diet with Se from SeMet and Na2SeO3, respectively. These results suggest that both SeMet and Na2SeO3 are equally utilized by grouper. The result also suggests that both SeMet and Na2SeO3 supplementation in diet enhance fish meat quality and its stability during storage.