楊原志 聶家全* 譚北平,2 董曉慧,2** 楊奇慧 遲淑艷

(1.廣東海洋大學(xué)水產(chǎn)學(xué)院水產(chǎn)動(dòng)物營(yíng)養(yǎng)與飼料實(shí)驗(yàn)室，湛江524088；2.南海生物資源開發(fā)與利用協(xié)同創(chuàng)新中心，廣州510006)

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硒源與硒水平對(duì)軍曹魚幼魚生長(zhǎng)性能、肝臟和血清抗氧化指標(biāo)及組織硒含量的影響

楊原志1聶家全1*譚北平1,2董曉慧1,2**楊奇慧1遲淑艷1

(1.廣東海洋大學(xué)水產(chǎn)學(xué)院水產(chǎn)動(dòng)物營(yíng)養(yǎng)與飼料實(shí)驗(yàn)室，湛江524088；2.南海生物資源開發(fā)與利用協(xié)同創(chuàng)新中心，廣州510006)

本試驗(yàn)旨在研究硒源和硒水平對(duì)軍曹魚幼魚生長(zhǎng)性能、肝臟和血清抗氧化指標(biāo)及組織硒含量的影響，以確定軍曹魚幼魚對(duì)不同硒源的最適需要量。在基礎(chǔ)飼料中分別添加0(對(duì)照)、0.3、0.6、0.9和1.2 mg/kg(以硒計(jì))的亞硒酸鈉(Se-S)或蛋氨酸硒(Se-Met)，配制9種試驗(yàn)飼料(共用對(duì)照飼料)，飽食投喂初始體重為(22.18±0.35) g的軍曹魚幼魚10周。每種試驗(yàn)飼料投喂3個(gè)網(wǎng)箱(重復(fù))，每個(gè)網(wǎng)箱放養(yǎng)30尾試驗(yàn)魚。結(jié)果表明：1)硒水平對(duì)特定生長(zhǎng)率(SGR)和增重率(WGR)有極顯著影響(P<0.01)，但對(duì)成活率(SR)和飼料系數(shù)(FCR)無顯著影響(P>0.05)；硒源及硒源與硒水平的交互作用對(duì)SGR、WGR、FCR和SR均無顯著影響(P>0.05)。SGR和WGR隨著硒水平的升高先升高后降低。2)硒水平極顯著影響肝臟谷胱甘肽過氧化物酶(GSH-Px)、谷胱甘肽還原酶(GR)活性和丙二醛(MDA)含量及血清GSH-Px活性(P<0.01)，并顯著影響血清GR活性(P<0.05)；硒源極顯著影響肝臟GR、總超氧化物歧化酶(T-SOD)、過氧化氫酶(CAT)活性和MDA含量及血清T-SOD活性(P<0.01)；硒源和硒水平的交互作用顯著影響肝臟CAT活性和MDA含量及血清T-SOD活性(P<0.05)。肝臟和血清GSH-Px活性隨著硒水平的升高呈先升高后穩(wěn)定趨勢(shì)，GR活性呈先下降后穩(wěn)定趨勢(shì)。2種硒源均在添加量為0.9 mg/kg時(shí)有最高的肝臟GSH-Px活性，最低的肝臟GR活性。肝臟CAT活性隨著硒水平的升高逐漸升高。3)脊椎骨、全魚和肝臟硒含量隨硒水平的升高而增加。硒源極顯著影響脊椎骨硒含量(P<0.01)，硒源和硒水平的交互作用極顯著影響肝臟和脊椎骨硒含量(P<0.01)。以蛋氨酸硒和亞硒酸鈉為硒源，通過二次回歸曲線分析得出飼料硒水平分別為1.29和1.46 mg/kg時(shí)軍曹魚幼魚可以獲得最大SGR。以SGR和全魚硒含量為判據(jù)，軍曹魚幼魚對(duì)蛋氨酸硒的生物利用率分別相當(dāng)于亞硒酸鈉的1.20和2.90倍。

軍曹魚幼魚；硒；生長(zhǎng)性能；抗氧化酶；硒沉積

硒在自然界中以無機(jī)硒或有機(jī)硒的形式存在，長(zhǎng)期被誤認(rèn)為是一種有毒物質(zhì)。1957年，Schwartz等[1]證實(shí)硒能預(yù)防因硒和/或維生素E缺乏導(dǎo)致的大白鼠的肝壞死。隨后人們相繼發(fā)現(xiàn)硒是參與構(gòu)成谷胱甘肽過氧化物酶(glutathione peroxidase，GSH-Px)的微量元素，其活性中心是硒半胱氨酸，該酶能夠把過氧化氫和脂質(zhì)過氧化產(chǎn)物分別轉(zhuǎn)換成水和脂醇，保護(hù)細(xì)胞膜和亞細(xì)胞膜的多不飽和磷脂免受過氧化損傷[2]；同時(shí)，硒還能促進(jìn)動(dòng)物生長(zhǎng)、提高繁殖性能、增強(qiáng)機(jī)體免疫力。

軍曹魚(Rachycentroncanadum)，隸屬鱸形目(Perciformes)，軍曹魚科(Rachycentridae)，軍曹魚屬(Rachycentron)，亦稱海鱺、海龍、海竹魚等，是大型肉食性魚類，具有生長(zhǎng)速度快、易于馴化攝食人工飼料、肉質(zhì)鮮美等特點(diǎn)，是我國(guó)南方沿海海水網(wǎng)箱養(yǎng)殖的重要品種之一。

目前，僅見軍曹魚對(duì)蛋氨酸硒需要量的研究報(bào)道，如Liu等[7]指出軍曹魚幼魚對(duì)蛋氨酸硒的需要量是0.788～0.811 mg/kg，未見硒源及硒水平對(duì)軍曹魚營(yíng)養(yǎng)生理影響的研究報(bào)道。因此，本試驗(yàn)擬研究飼料中不同硒源和硒水平對(duì)軍曹魚幼魚營(yíng)養(yǎng)生理作用的影響，旨在為軍曹魚幼魚營(yíng)養(yǎng)需要參數(shù)數(shù)據(jù)庫的完善及軍曹魚高效配合飼料的研制提供基礎(chǔ)數(shù)據(jù)。

1 材料與方法

1.1 試驗(yàn)設(shè)計(jì)與試驗(yàn)飼料

以脫維酪蛋白為主要蛋白質(zhì)源，玉米淀粉為糖源，玉米油、魚油為主要脂肪源，配制基礎(chǔ)飼料，基礎(chǔ)飼料組成及營(yíng)養(yǎng)水平見表1。在基礎(chǔ)飼料中分別添加源于亞硒酸鈉(購自國(guó)藥集團(tuán)化學(xué)試劑有限公司)或蛋氨酸硒(購自長(zhǎng)沙興嘉生物工程股份有限公司)的硒，添加水平分別為0(對(duì)照)、0.3、0.6、0.9和1.2 mg/kg，配制成9種試驗(yàn)飼料(共用對(duì)照飼料)，對(duì)照飼料中硒水平實(shí)測(cè)值為0.35 mg/kg，命名為C-0.35；添加亞硒酸鈉的4種飼料中硒水平實(shí)測(cè)值分別為0.68、1.09、1.26、1.65 mg/kg，并分別命名為Se-S-0.68、Se-S-1.09、Se-S-1.26、Se-S-1.65；添加蛋氨酸硒的4種飼料中硒水平實(shí)測(cè)值分別為0.67、1.02、1.33、1.69 mg/kg，并分別命名為Se-Met-0.67、Se-Met-1.02、Se-Met-1.33、Se-Met-1.69。

表1 基礎(chǔ)飼料組成及營(yíng)養(yǎng)水平(干物質(zhì)基礎(chǔ))

1)脫維酪蛋白(粗蛋白質(zhì)含量為94%)購自美國(guó)Sigma公司。Vitamin-free casein (CP content was 94%) obtained from Sigma Chemical Co., USA.

2)維生素預(yù)混料為每千克飼料提供The vitamin premix provided the following per kg of the diet: VB125 mg，VB245 mg，泛酸鈣 calcium pantothenate 60 mg，煙酸 nicotinic acid 200 mg，吡哆醇 pyridoxine 20 mg，生物素 biotin 1.20 mg，VB120.1 mg，葉酸 folic acid 20 mg，肌醇 inositol 800 mg，VA 32 mg，VD35 mg，VK310 mg，VE 120 mg。

3)無硒礦物質(zhì)預(yù)混料為每千克飼料提供The Se-free mineral premix provided the following per kg of the diet: CH3CHOHCOO2Ca·5H2O 6 100 mg，Na2HPO46 200 mg，NaF 2 mg，Ca(IO3)20.94 mg，CoCl2·6H2O (1%) 50 mg，CuSO4·5H2O 10 mg，MnSO4·H2O 60 mg，F(xiàn)eSO4·H2O 240 mg，ZnSO4·7H2O 180 mg，MgSO4·7H2O 1 200 mg，NaCl 100 mg。

4)實(shí)測(cè)值Measured values。

1.2 試驗(yàn)用魚與飼養(yǎng)管理

養(yǎng)殖試驗(yàn)在廣東省湛江市南三島海上浮式魚排中進(jìn)行，試驗(yàn)用軍曹魚幼魚購于廣東湛江市英利鎮(zhèn)海尾村養(yǎng)殖戶。軍曹魚幼魚暫養(yǎng)2周，期間投喂商品飼料。分組前停食24 h，隨機(jī)挑選規(guī)格一致、健康無病、初始體重為(22.18±0.35) g的試驗(yàn)魚進(jìn)行分組，根據(jù)試驗(yàn)設(shè)計(jì)，共分為9個(gè)組，每組3個(gè)重復(fù)，每個(gè)重復(fù)1個(gè)2.5 m×1.2 m×1.4 m的網(wǎng)箱，共27個(gè)網(wǎng)箱，每個(gè)網(wǎng)箱放養(yǎng)30尾魚。為減少試驗(yàn)誤差，所有網(wǎng)箱均隨機(jī)擺放。每種試驗(yàn)飼料投喂3個(gè)網(wǎng)箱，每天投喂2次(07:00、18:00)，日投喂量為試驗(yàn)魚體重的6%～9%。養(yǎng)殖期間水體溫度28～33 ℃，pH 7.6～7.8，鹽度29～31，溶氧濃度>6.0 mg/L，試驗(yàn)期10周。養(yǎng)殖海水中硒未檢出。

1.3 樣品采集和指標(biāo)測(cè)定

試驗(yàn)結(jié)束禁食24 h后，將各網(wǎng)箱試驗(yàn)魚全部撈出，丁香酚(1∶10 000)麻醉后稱重計(jì)數(shù)。每個(gè)網(wǎng)箱隨機(jī)抽取5尾魚，用2.5 mL的注射器從魚體圍心腔刺入，在心臟動(dòng)脈球處抽血，置于1.5 mL的Eppendorf管中，4 ℃、4 500 r/min離心10 min，吸取血清保存于-80 ℃冰箱中備用。每個(gè)網(wǎng)箱隨機(jī)抽取5尾魚解剖后迅速取出肝臟放入防凍管，立即放入液氮罐保存，后轉(zhuǎn)存于-80 ℃冰箱中備用。每個(gè)網(wǎng)箱隨機(jī)抽取8尾魚，去除內(nèi)臟后放入沸水中3 min，剝離肌肉，取出脊椎骨，用超純水沖洗去掉附著的肌肉。處理后的脊椎骨105 ℃烘干，粉碎過80目篩，乙醚抽提12 h去除脂肪，并再次105 ℃烘干[8]。

飼料成分分析：水分含量采用105 ℃常壓干燥法測(cè)定；粗蛋白質(zhì)含量采用凱氏定氮法(總氮×6.25)測(cè)定；粗脂肪含量采用索氏抽提法測(cè)定；粗灰分含量采用550 ℃馬弗爐灼燒法測(cè)定。

肝臟和血清抗氧化指標(biāo)測(cè)定：GSH-Px、谷胱甘肽還原酶(glutathione reductase，GR)、總超氧化物歧化酶(total superoxide dismutase，T-SOD)、過氧化氫酶(catalase，CAT)活性和丙二醛(malondialdehyde，MDA)含量采用南京建成生物工程研究所提供的試劑盒測(cè)定，樣品前處理、試劑配制及測(cè)定步驟均嚴(yán)格按照操作說明書執(zhí)行。

飼料、全魚、脊椎骨和肝臟中硒水平/含量測(cè)定：用硝酸和雙氧水充分消解定量樣品，用電感耦合等離子體-質(zhì)譜儀測(cè)定硒含量。

1.4 計(jì)算公式

特定生長(zhǎng)率(specific growth rate，SGR,%/d)=

100×(ln試驗(yàn)期末均重-ln試驗(yàn)期初均重)/試驗(yàn)天數(shù)；

增重率(weight gain rate，WGR,%)=

100×(試驗(yàn)期末均重-試驗(yàn)期初均重)/試驗(yàn)期初均重；

成活率(survival rate，SR，%)=

100×試驗(yàn)期末魚尾數(shù)/試驗(yàn)期初魚尾數(shù)；

飼料系數(shù)(feed conversion rate，F(xiàn)CR)=

總攝食量/(試驗(yàn)期末總重+死亡魚總重-試驗(yàn)期初總重)。

1.5 統(tǒng)計(jì)分析

試驗(yàn)結(jié)果用平均值±標(biāo)準(zhǔn)誤表示，采用SPSS 16.0的一般線性模型(GLM)進(jìn)行雙因素方差分析，模型的主效應(yīng)分析包括硒源、硒水平及兩者之間的交互作用。P<0.05表示差異顯著，P<0.01表示差異極顯著。

2 結(jié) 果

2.1 硒源和硒水平對(duì)軍曹魚幼魚生長(zhǎng)性能的影響

由表2可知，硒源對(duì)SGR、WGR、FCR和SR均無顯著影響(P>0.05)；硒水平對(duì)SGR和WGR有極顯著影響(P<0.01)，但對(duì)SR和FCR無顯著影響(P>0.05)。硒源和硒水平的交互作用對(duì)SGR、WGR、FCR和SR均無顯著影響(P>0.05)。SGR和WGR隨著硒水平的升高先升高后逐漸降低。分別以蛋氨酸硒和亞硒酸鈉為硒源，通過二次回歸曲線分析得出飼料硒水平分別為1.29和1.46 mg/kg時(shí)軍曹魚幼魚可以獲得最大SGR(圖1)；以SGR為判據(jù)時(shí)，軍曹魚幼魚對(duì)蛋氨酸硒的生物利用率相當(dāng)于亞硒酸鈉的1.20倍(蛋氨酸硒：y=0.209x+2.111，R2=0.98；亞硒酸鈉：y=0.175x+2.218，R2=0.99；x為飼料硒水平，y為SGR)。

表2 硒源和硒水平對(duì)軍曹魚幼魚生長(zhǎng)性能的影響

同列數(shù)據(jù)肩標(biāo)無字母或相同字母表示差異不顯著(P>0.05)，不同小寫字母表示差異顯著(P<0.05)。下表同。

In the same column, values with no letter or the same letter superscripts mean no significant difference (P>0.05), while with different small letter superscripts mean significant difference (P<0.05). The same as below.

圖1 飼料硒水平與軍曹魚幼魚特定生長(zhǎng)率的關(guān)系(2種硒源)

2.2 硒源和硒水平對(duì)軍曹魚幼魚肝臟和血清抗氧化指標(biāo)的影響

由表3可知，硒源極顯著影響肝臟GR、T-SOD、CAT活性和MDA含量及血清T-SOD活性(P<0.01)，但對(duì)肝臟GSH-Px活性及血清GSH-Px、GR、CAT活性和MDA含量無顯著影響(P>0.05)。硒水平極顯著影響肝臟GSH-Px、GR活性和MDA含量及血清GSH-Px活性(P<0.01)，顯著影響血清GR活性(P<0.05)，但對(duì)肝臟T-SOD、CAT活性及血清T-SOD、CAT活性和MDA含量無顯著影響(P>0.05)；硒源和硒水平的交互作用對(duì)肝臟CAT活性、MDA含量和血清T-SOD活性有顯著影響(P<0.05)，但對(duì)肝臟GSH-Px、GR、T-SOD活性及血清GSH-Px、GR、CAT活性和MDA含量無顯著影響(P>0.05)。肝臟和血清GSH-Px活性隨著硒水平的升高表現(xiàn)為先升高后穩(wěn)定的趨勢(shì)，GR活性則表現(xiàn)為先下降后穩(wěn)定的趨勢(shì)。2種硒源中，分別以Se-S-1.26組和Se-Met-1.33組的肝臟GSH-Px活性最高，并均顯著高于對(duì)照組(C-0.35組)(P<0.05)；同時(shí)這2組的肝臟GR活性最低，并均顯著低于對(duì)照組(P<0.05)；肝臟CAT活性隨著硒水平的升高逐漸升高，在以亞硒酸鈉為硒源的組中，Se-S-1.65組肝臟CAT活性顯著高于除Se-S-1.26組外的其他3組(P<0.05)；在以蛋氨酸硒為硒源的組中，Se-Met-1.69組肝臟CAT活性顯著高于其他各組(P<0.05)。各組間血清CAT活性無顯著差異(P>0.05)。

2.3 硒源和硒水平對(duì)軍曹魚幼魚組織硒含量的影響

由表4可知，硒源極顯著的影響脊椎骨硒含量(P<0.01)，但對(duì)全魚和肝臟硒含量無顯著影響(P>0.05)。硒水平對(duì)脊椎骨、全魚和肝臟硒含量有極顯著影響(P<0.01)，脊椎骨、全魚和肝臟硒含量隨著飼料硒水平的升高而升高。硒源和硒水平的交互作用對(duì)全魚硒含量沒有顯著影響(P>0.05)，但對(duì)肝臟和脊椎骨硒含量有極顯著影響(P<0.01)。以全魚硒含量為判據(jù)時(shí)，軍曹魚幼魚對(duì)蛋氨酸硒的生物利用率相當(dāng)于亞硒酸鈉的2.90

倍(蛋氨酸硒：y=0.938x+0.052，R2=0.99；亞硒酸鈉：y=0.323x+2.252，R2=0.99；x為飼料硒水平，y為全魚硒含量)。

表3 硒源和硒水平對(duì)軍曹魚幼魚肝臟和血清抗氧化指標(biāo)的影響

3 討 論

3.1 硒源和硒水平對(duì)軍曹魚幼魚生長(zhǎng)性能的影響

表4 硒源和硒水平對(duì)軍曹魚幼魚組織硒含量的影響

3.2 硒源和硒水平對(duì)軍曹魚幼魚肝臟和血清抗氧化指標(biāo)的影響

MDA是脂質(zhì)氧化產(chǎn)物，經(jīng)常用作氧化脅迫指標(biāo)之一[33]。Zhu等[22]對(duì)大口黑鱸的研究發(fā)現(xiàn)飼料中硒水平對(duì)肝臟MDA含量沒有顯著影響，并認(rèn)為這是由于飼料中有較多的抗氧化劑(維生素E：400 mg/kg，維生素C：1 000 mg/kg)與活性氧起反應(yīng)從而掩蓋掉硒在體內(nèi)的抗氧化作用所致。在本試驗(yàn)中，硒水平和硒源的交互作用對(duì)肝臟MDA含量有顯著影響，對(duì)血清MDA含量沒有顯著影響。亞硒酸鈉組和蛋氨酸硒組的肝臟MDA含量均隨著飼料中硒水平的升高先下降后升高。這可能與本試驗(yàn)中抗氧化劑(維生素：120 mg/kg，維生素C：350 mg/kg)含量相對(duì)較低有關(guān)。當(dāng)飼料中硒達(dá)到較高水平時(shí)，可能超出了魚體的需要量，且對(duì)魚體有一定的毒害作用，因此造成魚體氧自由基代謝紊亂，T-SOD和GSH-Px活性下降，自由基含量升高，MDA含量升高。這與人類硒營(yíng)養(yǎng)研究中硒生物效應(yīng)與硒水平的關(guān)系相似，即當(dāng)硒水平在適宜范圍內(nèi)時(shí)能夠有效地清除生物體內(nèi)的活性自由基，而當(dāng)硒水平較高時(shí)則會(huì)催化產(chǎn)生活性自由基[34]。中華絨螯蟹[19]血清、肝臟中MDA含量及鱸魚[21]血清中MDA含量隨飼料硒水平的升高呈先降低后升高趨勢(shì)，與本試驗(yàn)結(jié)果類似；而凡納濱對(duì)蝦血清MDA含量則隨飼料硒水平的升高呈逐漸下降趨勢(shì)[26]。

在魚體內(nèi)GSH-Px、T-SOD和CAT共同起作用，清除超氧陰離子、羥自由基和過氧化氫，減少脂質(zhì)過氧化物的損害。在本試驗(yàn)中，肝臟CAT活性隨著硒水平的升高逐漸升高，Se-S-1.65組和Se-Met-1.69組的肝臟CAT活性高于同一硒源的其他組；肝臟T-SOD活性隨硒水平的升高先升高后降低，2種硒源中分別以Se-S-1.26組和Se-Met-1.33組肝臟T-SOD活性最高，這表明飼料中添加硒能夠提高軍曹魚幼魚體內(nèi)CAT和T-SOD的活性。Monteiro等[35]發(fā)現(xiàn)飼料補(bǔ)充硒能夠提高缺簾魚(Bryconcephalus)肝臟CAT和T-SOD活性，共同抵抗甲基對(duì)硫磷毒性的氧化脅迫，未添加硒組肝臟T-SOD和CAT活性降低。在異育銀鯽飼料中添加硒至1 mg/kg時(shí)，血清T-SOD活性達(dá)到最大值，添加至5 mg/kg時(shí)血清T-SOD活性顯著降低；飼料中添加硒對(duì)異育銀鯽血清CAT活性沒有產(chǎn)生顯著影響，但血清CAT活性有隨飼料硒水平的升高而下降的趨勢(shì)，表明飼料中過量的硒降低了血清CAT和T-SOD活性[10]。鱸魚血清和肝臟超氧化物歧化酶(SOD)活性隨飼料硒水平的升高呈先上升后下降趨勢(shì)[21]。飼料中添加硒提高了吉富羅非魚(Oreochromisniloticus)血清中CAT和T-SOD的活性[36]。

3.3 硒源和硒水平對(duì)軍曹魚幼魚組織硒含量的影響

4 結(jié) 論

① 以亞硒酸鈉和蛋氨酸硒為硒源，通過二次回歸曲線分析得出飼料硒水平分別為1.46和1.29 mg/kg時(shí)軍曹魚幼魚可以獲得最大SGR。

② 以SGR為判據(jù)時(shí)，軍曹魚幼魚對(duì)蛋氨酸硒的生物利用率相當(dāng)于亞硒酸鈉的1.20倍；以全魚硒含量為判據(jù)時(shí)，軍曹魚幼魚對(duì)蛋氨酸硒的生物利用率相當(dāng)于亞硒酸鈉的2.90倍。

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*Contributed equally

**Corresponding author, professor, E-mail: dongxiaohui2003@163.com

(責(zé)任編輯 菅景穎)

Effects of Selenium Source and Selenium Level on Growth Performance, Liver and Serum Antioxidant Indices and Selenium Content in Tissues of Juvenile Cobia (Rachycentroncanadum)

YANG Yuanzhi1NIE Jiaquan1*TAN Beiping1,2DONG Xiaohui1,2**YANG Qihui1CHI Shuyan1

(1.LaboratoryofAquaticAnimalNutritionandFeed,FisheriesCollege,GuangdongOceanUniversity,Zhanjiang524088,China; 2.SouthChinaSeaBio-ResourceExploitationandUtilizationCollaborativeInnovationCenter,Guangzhou510006,China)

A feeding trial was carried out to investigate the effects of selenium (Se) source and Se level on growth performance, liver and serum antioxidant indices and Se content in tissues of juvenile cobia (Rachycentroncanadum), in order to determine the Se requirement from different Se sources of juvenile cobia. Nine experimental diets (control diet was shared) were prepared by supplementing 0 (control), 0.3, 0.6, 0.9 and 1.2 mg/kg Se from sodium selenite (Se-S) or selenium methionine (Se-Met), respectively. Juvenile cobia with an initial body weight of (22.18±0.35) g were fed to satiation for 10 weeks. Fish in three cages (replicates) were fed a kind of experimental diet and 30 fish in a cage. The results showed as follows: 1) Se level extremely significantly affected the weight gain rate (WGR) and specific growth rate (SGR) (P<0.01), but did not significantly affected the feed conversion ratio (FCR) and survival rate (SR) (P>0.05). The SGR, WGR, FCR and SR were not affected by Se source and the interaction of Se source and Se level (P>0.05). With the Se level increasing, the SGR and WGR were increased firstly and then decreased. 2) The glutathione peroxidase (GSH-Px), glutathione reductase (GR) activities and malondialdehyde (MDA) content in liver and GSH-Px activity in serum were extremely significantly affected by Se level (P<0.01), and GR activity in serum was significantly affected by Se level (P<0.05). The GR, total superoxide dismutase (T-SOD), catalase (CAT) activities and MDA content in liver and T-SOD activity in serum were extremely significantly affected by Se source (P<0.01). The interaction of Se level and Se source had significant effects on liver CAT activity, MDA content and serum T-SOD activity (P<0.05). With the Se level increasing, the activity of GSH-Px in liver and serum was increased firstly and then stabilized, and the GR activity in liver and serum was firstly decreased and then stabilized. The highest GSH-Px activity and the lowest GR activity in liver were obtained at the 0.9 mg/kg added level from two Se sources. The CAT activity in liver was increased with the Se level increasing. 3) Se content in vertebrae, liver and whole body was increased with Se level increasing. Se content in vertebrae was extremely significantly affected by Se source (P<0.01). Se content in liver and vertebrae was extremely significantly affected by the interaction of Se level and Se source (P<0.01). In conclusion, using Se-Met and Se-S as Se sources, the highest SGR of juvenile cobia can be obtained when dietary Se level is 1.29 and 1.46 mg/kg, respectivly, by quadratic polynomial regression equations. With SGR and Se content in whole body as dependent variables, the biological utilization of Se-Met is 1.20 and 2.90 times that of Se-S, respectivly.[ChineseJournalofAnimalNutrition, 2016, 28(12)：3894-3904]

juvenile cobia (Rachycentroncanadum); selenium; growth performance; antioxidant enzyme; selenium accumulation

10.3969/j.issn.1006-267x.2016.12.022

2016-06-12

公益性行業(yè)(農(nóng)業(yè))科研專項(xiàng)(201003020)；廣東省農(nóng)業(yè)攻關(guān)(2012B020307005)；廣東省教育廳引進(jìn)人才項(xiàng)目(粵財(cái)教[2013]246號(hào))

楊原志(1974—)，男，山東鄆城人，助理研究員，碩士，從事水產(chǎn)動(dòng)物營(yíng)養(yǎng)與飼料研究。E-mial： hdyyz@163.com

*同等貢獻(xiàn)作者

**通信作者：董曉慧，教授，博士生導(dǎo)師，E-mail: dongxiaohui2003@163.com

S963

A

1006-267X(2016)12-3894-11