高植物蛋白質飼料中添加不同型態硒對龍膽石斑成長、硒濃度、抗氧化活性及肝臟與腸道組織學變化之影響

本研究探討高植物蛋白質飼料中添加不同型態硒對龍膽石斑(Epinephelus lanceolatus)成長表現、魚體組織硒濃度、肝臟抗氧化活性、肝臟及腸道組織學變化之影響。實驗一共計8組實驗飼料，對照組飼料(F組)以魚粉作為主要蛋白源；以豆粉取代40%魚粉蛋白之基礎飼料(S, 控制組)中分別添加5及10 mg Se/kg之亞硒酸鈉(Na2SeO3, S+5N組, S+10N組)、甲硫胺酸硒(SeMet, S+5M組, S+10M組)及10與20 mg Se/kg之羥基甲硫胺酸硒(OH-SeMet, S+10O組, S+20O組)。實驗採3重複，共計24缸，每缸放養8尾石斑稚魚(平均初重16.51 ± 0.08 g)，以循環水系統進行為期8週的成長實驗。結果顯示，增重率以S+10M組顯著(p < 0.05)高於F及S+5M兩組，飼料效率以S+5N及S+10M兩組顯著高於S+5M組，F組之肝體比(HSI)顯著高於其他組別。肝細胞直徑，除S+10O組外，其餘組別均顯著低於F組。肝臟麩胱甘肽過氧化酶活性(GPx)以F及S+20O兩組顯著高於S及S+5M兩組，肝臟硫代巴必妥酸反應受質(TBARS)以S組顯高於S+10N、S+10M及S+20O三組。隨著飼料中硒濃度增加，全魚、肌肉及肝臟硒濃度也隨之增加，且相較於餵食無機硒(Na2SeO3)組的魚隻，餵食有機硒(SeMet及OH-SeMet)的組別，各組織中硒蓄積量較高。實驗二同樣以全魚粉組飼料作為對照組(F組)，以豆粉取代40%魚粉蛋白之基礎飼料(S, 控制組)中分別添加0.3、0.6及1.0 mg Se/kg之SeMet (S+0.3M、S+0.6M及S+1.0M組)或OH-SeMet (S+0.3O、S+0.6O及S+1.0O組)。實驗飼料共8組，每組三重複共計24缸(8 fish/tank)，魚隻平均初重為25.99 ± 0.04 g，同樣於海水循環系統中進行為期8週之成長實驗。增重率結果顯示F組顯著高於所有組別，其餘組別中則以S+0.6O組顯著高於S+0.6M組。攝食量與肝體比均以F組顯著高於所有組別。肝臟GPx活性除S+0.6M組外，其餘組均顯著高於S組，觸酶活性(CAT)以S及S+0.6M兩組顯著低於所有組別，超氧化物歧化酶活性(SOD)以F、S+1.0M及S+1.0O三組顯著高於S及S+0.6M兩組，TBARS值以S及S+0.6M兩組顯著高於其餘各組。隨著飼料中硒添加量上升，全魚體、肌肉及肝臟硒濃度亦隨之增加。在相同添加劑量下，OH-SeMet各組之全魚體硒保留率均顯著高於添加SeMet的組別。本研究結果顯示含高植物性蛋白飼料中(豆粉取代40%魚粉蛋白)添加硒，可提高肝臟抗氧化酵素活性並降低肝臟氧化壓力，且有機硒的生物利用性優於無機硒。此外，組織硒濃度及全魚體硒保留率均以羥基甲硫胺酸硒的生物利用性優於甲硫胺酸硒。

關鍵字

龍膽石斑；豆粉；亞硒酸鈉；甲硫胺酸硒；羥基甲硫胺酸硒；硒濃度；抗氧化活性

並列摘要

The study evaluated the effects of dietary selenium (Se) sources on growth, selenium concentration, antioxidant activities and liver and intestine histological changes of giant grouper (Epinephelus lanceolatus) fed a diet with high plant-protein. In Experiment 1, the basal diet containing soybean meal (replaced 40% soybean meal) (S, control diet) was supplemented with 5 and 10 mg Se/kg of sodium selenite (Na2SeO3, S+5N and S+10N diets) and selenomethionine (SeMet, S+5M and S+10M diets), and 10 and 20 mg Se/kg of hydroxy-selenomethionine (OH-SeMet, S+10O and S+20O diets). All fish meal diet (F diet) was also included for comparison. Total of 8 experimental diets were each fed to triplicate groups of juvenile grouper (initial weight: 16.51 ± 0.08 g) in a seawater recirculation system for 8 weeks. Weight gain was higher (p < 0.05) in fish fed the S+10M diet than that in fish fed F and S+5M diets. Feed efficiency was higher in fish fed S+5N and S+10M diets than that in fish fed the S+5M diet. Hepatosomatic index (HSI) was higher in the F diet than other dietary treatments. Besides the S+10O diet, fish fed the F diet had higher diameter of hepatocyte than other dietary diets. Hepatic glutathione peroxidase (GPx) activity was higher in fish fed F and S+20O diets than that in fish fed S and S+5M diets. Fish fed the S diet showed higher hepatic thiobarbituric acid reactive substance (TBARS) value than fish fed S+10N, S+10M and S+20O diets. Whole body, muscle and hepatic Se concentrations increased with the increment of dietary Se supplementation levels. Fish fed diets with SeMet or OH-SeMet showed higher tissue Se concentration than fish fed diets with Na2SeO3. In Experiment 2, the same basal diet (S group) was supplemented with 0.3, 0.6 and 1.0 mg Se/kg of SeMet (S+0.3M, S+0.6M and S+1.0M groups) or OH-SeMet (S+0.3O, S+0.6 O and S+1.0 O groups). All fish meal diet (F group) was also included for comparison. Total of 8 experimental diets were each fed to triplicate groups of juvenile grouper (initial weight: 25.99 ± 0.04 g) in a seawater recirculation system for 8 weeks. Fish fed the F group had higher weight gain than other dietary treatments, in which S+0.6O group had higher weight gain than S+0.6M group. Feed intake and HSI were higher in fish fed the F group than those in other groups. Besides the S+0.6M group, other dietary treatments had higher hepatic GPx activity than fish fed the S group. Catalase (CAT) activity was lower in fish fed S and S+0.6M group than other groups. Superoxide dismutase (SOD) activity was higher in fish fed F, S+1.0M and S+1.0O groups than that in fish fed S and S+0.6M groups. Hepatic TBARS value was higher in fish fed S and S+0.6M groups than other dietary groups. Whole body, muscle and hepatic Se concentrations increased with the increment of dietary Se supplementation levels. At the same Se supplementatioin level, whole body Se retention was higher in fish fed diets with OH-SeMet than that in fish fed diets with SeMet. Results indicate that the Se supplementation could not improve growth performance, liver and intestinal morphology in grouper fed diet with high level of sybean meal, but enhance hepatic antioxidant enzyme activity and reduced oxidative stress. Organic Se show higher bioavailability than inorganic Se for giant grouper. Moreover, although the effects of dietary SeMet and OH-SeMet supplementation on antioxidant status are similar, tissue Se accumulation and retention are better in OH-SeMet than SeMet for giant grouper.