【作者】 张健；

【导师】 许东晖；

【作者基本信息】 中山大学 ， 海洋生物学， 2012， 博士

【摘要】 本论文主要研究了六种免疫增强剂对凡纳滨对虾幼虾生长、免疫及抗应激能力的影响。本论文包括以下六个方面的内容：1．通过8周的室内水族缸生长实验以及随后的急性应激实验，评估虾青素（Astaxanthin，AX）对凡纳滨对虾生长、免疫及抗缺氧应激能力的影响。实验虾初始体重为1.01±0.001g。虾青素的添加有效浓度分别为0、25、50、75、100、125、150mg kg-1饲料。共设7个处理组，每组设5个平行，每个水族缸放30尾虾苗，每天饲喂4次。生长实验结束后，对实验虾进行了1h的缺氧应激实验。结果表明：当AX添加量为125mg kg-1和150mg kg-1时，对虾的增重率（Weight Gain，WG）和特定生长率（Specific Growth Rate，SGR）显著高于空白对照组（P<0.05）。同时，当AX添加量为125mg kg-1和150mg kg-1时，对虾血淋巴中的总抗氧化能力（TotalAntioxidant Status，TAS）显著高于空白对照组（P<0.05），超氧化物歧化酶（SuperoxideDismutase，SOD）和过氧化氢酶（Catalase，CAT）活性显著低于空白对照组（P<0.05）。然而，各处理组对虾血淋巴中的谷草转氨酶（Aspartate Transaminase，AST）、谷丙转氨酶（Alanine Transaminase，ALT）活性无显著性差异（P>0.05）。1h缺氧应激实验后，当AX添加量为75、100、125和150mg kg-1时，对虾的存活率显著高于空白对照组（P<0.05）。与常氧状态相比，缺氧状态下各处理组缺氧诱导因子(Hypoxia-inducible factor alpha, HIF^-1α) mRNA的表达量显著下降（P<0.05），但AX150mg kg^-1处理组的表达量仍高于空白对照组（P<0.05）；SOD mRNA的表达量显著下降（P<0.05），但AX125mg kg^-1和150mg kg^-1处理组的表达量仍高于空白对照组（P<0.05）；CAT mRNA的表达量显著下降（P<0.05），但AX100、125和150mg kg^-1处理组的表达量仍高于空白对照组（P<0.05）；然而，缺氧状态下各处理组热应激蛋白70（70-kDa heat-shock protein, Hsp70）mRNA表达量显著上升（P<0.05），但AX150mg kg^-1处理组的表达量显著低于空白对照组（P<0.05）。以上结果显示，在饲料中添加有效浓度为125mg kg^-1和150mg kg^-1的虾青素，可显著提高凡纳滨对虾的生长、免疫和抗低氧应激能力。2.通过8周的室内水族缸生长实验以及随后的急性应激实验，评估壳聚糖（Chitosan）对凡纳滨对虾生长、免疫及抗氨氮应激能力的影响。实验虾初始体重为0.71±0.00g。壳聚糖的添加浓度分别为0、1.0、2.0、3.0、4.0、5.0和6.0g kg^-1饲料。共设7个处理组，每组设5个平行，每个水族缸放30尾虾苗，每天饲喂4次。生长实验结束后，对实验虾进行了总氨浓度为120mg L^-1的氨氮应激实验，持续时间为72h。结果表明：7个处理组的WG和SGR都无显著性差异（P>0.05）。同时，当壳聚糖添加量为3.0g kg^-1时，对虾血淋巴中酚氧化酶（Phenoloxidase，PO）和溶菌酶（Lysozyme，LSZ）活性显著高于空白对照组（P<0.05）。72h的氨氮应激实验后，除了壳聚糖2.0g kg^-1处理组外，其他壳聚糖添加组的存活率均显著高于空白对照组（P<0.05）。以上结果显示，在饲料中添加壳聚糖，虽对凡纳滨对虾的生长无显著性的影响，但可显著性提高凡纳滨对虾的免疫能力，并增强凡纳滨对虾对氨氮应激的抵抗力，添加适宜浓度为3.0g kg^-1。3．通过8周的室内水族缸生长实验以及随后的急性应激实验，评估果寡糖（Fructooligosaccharides，FOS）对凡纳滨对虾生长、免疫及抗氨氮应激能力的影响。实验虾初始体重为0.60±0.00g。果寡糖的添加浓度分别为0、0.5、1.0、1.5、2.0和2.5g kg^-1饲料。共设6个处理组，每组设4个平行，每个水族缸放30尾虾苗，每天饲喂4次。生长实验结束后，对实验虾进行了总氨浓度为120mg L^-1的氨氮应激实验，持续时间为60h。结果表明：当FOS添加量为0.5g kg^-1和1.0g kg^-1时，对虾的WG和SGR显著高于空白对照组（P<0.05）。同时，当FOS添加量为1.0g kg^-1时，对虾血淋巴的PO酶和碱性磷酸酶（Alkaline Phosphatase，AKP）活性显著高于空白对照组（P<0.05）；当FOS添加量为1.0、1.5、2.0、2.5g kg^-1时，对虾血淋巴的酸性磷酸酶（Acid Phosphatase，ACP）活性显著高于空白对照组（P<0.05）。60h氨氮应激实验后，所有添加FOS的处理组对虾的存活率显著高于空白对照组（P<0.05）。以上结果显示，在饲料中添加果寡糖，可显著提高凡纳滨对虾的生长、免疫和抗氨氮应激的抵抗力，添加适宜浓度为1.0g kg^-1。4．通过8周的室内水泥池生长实验以及随后的急性应激实验，评估甘露寡糖（Mannan Oligosaccharide，MOS）对凡纳滨对虾生长、免疫及抗氨氮应激能力的影响。实验虾初始体重为2.52±0.01g。甘露寡糖的添加有效浓度分别为0、0.12、0.24、0.48、0.72和0.96g kg^-1饲料。共设6个处理组，每组设6个平行，每个水泥池放30尾虾苗，每天饲喂4次。生长实验结束后，对实验虾进行了总氨浓度为160mg L^-1的氨氮应激实验，持续时间为24h。结果表明：当MOS添加量为0.24、0.48、0.72和0.96g kg^-1时，对虾的WG和SGR显著高于空白对照组（P<0.05），其中以MOS添加量为0.24g kg^-1时，对虾的WG和SGR最高。对虾肠道的电镜检测结果显示，所有添加MOS的处理组对虾的上皮细胞绒毛密度显著高于空白对照组（P<0.05）；当MOS添加量为0.24、0.48、0.72和0.96g kg^-1时，对虾的上皮细胞绒毛长度也显著高于空白对照组（P<0.05）。24h氨氮应激实验后，当MOS添加量为0.24、0.48、0.72和0.96g kg^-1时，对虾的存活率显著高于空白对照组（P<0.05），其中以MOS添加量为0.48g kg^-1时存活率最高。氨氮应激实验0-24h检测的PO酶和SOD酶活性，结果显示；0h时，MOS添加量为0.48g kg^-1时，对虾的PO酶活性显著高于空白对照组（P<0.05）。MOS添加量为0.48、0.72和0.96g kg^-1时，对虾的SOD酶活性显著高于空白对照组（P<0.05）。其中，MOS添加量为0.48g kg^-1时，对虾的SOD酶活性最高。24h后，与0h相比，所有处理组的PO酶活性显著降低（P<0.05）。但MOS添加量为0.48g kg^-1处理组对虾的PO酶活性仍显著高于空白对照组（P<0.05）；所有处理组的SOD酶活性也显著降低（P<0.05），但各处理组之间无显著性差异（P>0.05）。以上所有结果显示，在饲料中添加甘露寡糖，可显著提高凡纳滨对虾的生长、免疫和抗氨氮应激的抵抗力，添加适宜浓度为0.24-0.48g kg^-1。5．通过8周的室内水族缸生长实验以及随后的急性应激实验，评估β-葡聚糖（β-glucan）对凡纳滨对虾生长、免疫及抗氨氮应激能力的影响。实验虾初始体重为1.00±0.00g。将β-葡聚糖的不同浓度和不同投喂方式结合，设置1个对照组和6个处理组，分别为：（1）对照组：基础饲料每天投喂；（2）处理组1：0.3g kg^-1β-葡聚糖每天投喂；（3）处理组2：0.6g kg^-1β-葡聚糖每天投喂；（4）处理组3：0.9g kg^-1β-葡聚糖每天投喂；（5）处理组4：基础饲料5d+0.3g kg^-1β-葡聚糖投喂2d；（6）处理组5：基础饲料5d+0.6g kg^-1β-葡聚糖投喂2d；（7）处理组6：基础饲料5d+0.9g kg^-1β-葡聚糖投喂2d。每个处理组各设5个平行，每个水族缸放30尾虾苗。实验期间每天投喂4次。生长实验结束后，对实验虾进行了总氨浓度为160mg L^-1的氨氮应激实验，持续时间为24h。结果表明：间隔投喂β-葡聚糖的处理组4、处理组5和处理组6对虾的WG和SGR显著高于对照组（P<0.05）。生长实验结束后，处理组5和处理组6对虾肝胰腺的PO酶mRNA表达量显著高于对照组（P<0.05）。所有β-葡聚糖处理组对虾肝胰腺的SOD酶mRNA表达量显著高于对照组（P<0.05）。对照组与6个β-葡聚糖处理组对虾肝胰腺的LSZ mRNA表达水平无显著性差异（P>0.05）。所有β-葡聚糖处理组对虾肝胰腺的脂多糖和葡聚糖结合蛋白(lipopolysaccharide-and β^-1,3-glucan binding protein，LGBP) mRNA表达量显著高于对照组（P<0.05）；同时，在所有β-葡聚糖处理组中，处理组2、处理组3、处理组4、处理组5和处理组6对虾肝胰腺的LGBP mRNA表达量显著高于处理组1（P<0.05）。24h氨氮应激实验后，虾的存活率以间隔投喂β-葡聚糖的处理组4、处理组5和处理组6显著高于对照组（P<0.05）。其中，在处理组1-处理组6中，间隔投喂β-葡聚糖的处理组5和处理组6的存活率显著高于每天投喂β-葡聚糖的处理组1、处理组2和处理组3（P<0.05）。氨氮应激实验0-24h检测的PO酶、SOD酶和LSZ酶活性结果显示：0h时，间隔投喂β-葡聚糖的处理组5和处理组6对虾的PO酶活性显著高于对照组（P<0.05）；所有β-葡聚糖处理组对虾的SOD酶活性显著高于对照组（P<0.05）；对照组和所有β-葡聚糖处理组对虾的溶菌酶活性无显著性差异（P>0.05）。24h时，与0h相比，对照组和所有β-葡聚糖处理组对虾的PO酶活性显著降低（P<0.05）。但处理组6对虾的PO酶活性仍显著高于对照组（P<0.05）；对照组和所有β-葡聚糖处理组对虾的SOD酶活性无显著性变化，且各处理组之间无显著性差异（P>0.05）；处理组4、处理组5和处理组6对虾的溶菌酶活性显著提高（P<0.05），且24h时，处理组2、处理组3、处理组4、处理组5和处理组6对虾的溶菌酶活性显著高于对照组（P<0.05）。以上所有结果显示，在饲料中添加有效浓度为0.3-0.9g kg^-1β-葡聚糖，并采用投喂2d，间隔5d的方法可显著提高凡纳滨对虾的生长、免疫和抗氨氮应激的抵抗力。6．通过8周的室内水泥池生长实验以及随后的急性缺氧实验，评估壳聚糖锌（Chitosan-Zn）对凡纳滨对虾生长、免疫及抗缺氧应激能力的影响。实验虾初始体重为1.49±0.01g。壳聚糖锌的添加浓度分别为25、50和100mg kg^-1饲料，并设置空白对照组和3000mg kg^-1壳聚糖组。共设5个处理组，每组设5个平行，每个水泥池放40尾虾苗，每天饲喂4次。生长实验结束后，对实验虾进行了缺氧应激实验，持续时间为6h。结果表明：5个处理组的WG和SGR都无显著性差异（P>0.05）。添加壳聚糖3000mg kg^-1和添加壳聚糖锌100mg kg^-1两个处理组对虾的PO酶活性显著高于空白对照组（P<0.05）；对虾的SOD酶活性各处理组无显著性差异（P>0.05）；对虾的LSZ酶活性以添加壳聚糖3000mg kg^-1和添加壳聚糖锌100mgkg^-1两个处理组较高，与空白对照组有显著性差异（P<0.05）。添加壳聚糖3000mgkg^-1和添加壳聚糖锌100mg kg^-1两个处理组对虾肝胰腺的PO酶mRNA表达量显著高于空白对照组（P<0.05）；添加壳聚糖锌100mg kg^-1处理组对虾肝胰腺的SOD酶mRNA表达量显著高于空白对照组（P<0.05）；对虾肝胰腺的LSZ mRNA表达量以添加壳聚糖3000mg kg^-1、壳聚糖锌50mg kg^-1和壳聚糖锌100mg kg^-1三个处理组较高，并与空白对照组有显著性差异（P<0.05）。6h缺氧应激后，添加壳聚糖锌100mg kg^-1处理组对虾的存活率显著高于空白对照组（P<0.05），与其他各处理组无显著性差异（P>0.05）。以上所有结果显示，饲料中添加100mg kg^-1的壳聚糖锌虽然不能显著提高凡纳滨对虾生长的效率，但能显著提高凡纳滨对虾血淋巴PO酶和LSZ酶的活性，以及肝胰腺PO、SOD和LSZ mRNA的表达水平，进而提高凡纳滨对虾对缺氧应激的抵抗力，提高成活率。更多还原

【Abstract】 A series studies were conducted to evaluate the effects of dietary immunostimulantson growth, non-specific immune response and stress resistance of juvenile Pacific whiteshrimp Litopenaeus vannamei. The results obtained can be briefly summarized asfollows:1. An8-week feeding trial and dissolved oxygen stress subsequently conducted toevaluate the effects of dietary astaxanthin （AX） on growth, non-specific immuneresponse and stress resistance of juvenile Pacific white shrimp Litopenaeus vannamei.Seven diets with or without AX supplementation namely Control （Basal feed （BF）without AX）, AX25（BF+25mg AX kg-1diet）, AX50（BF+50mg AX kg-1diet）, AX75（BF+75mg AX kg-1diet）, AX100（BF+100mg AX kg-1diet）, AX125（BF+125mg AXkg-1diet） and AX150（BF+150mg AX kg-1diet） were fed to Litopenaeus vannamei （1.01±0.00g） for8weeks in35tanks （30shrimp per tank）. The results showed that shrimp fedAX125and AX150diets had higher （P<0.05） weight gain （WG）, specific growth rate（SGR）, total antioxidant status （TAS） and lower （P<0.05） superoxide dismutase （SOD）,catalase （CAT） than shrimp fed control diet. However, Aspartate aminotransferase （AST）and alanine aminotransferase （ALT） activities were not significantly different （P>0.05） between AX-supplemented groups and control group. After low dissolved oxygen stressfor1h, survival rate of shrimp fed AX75, AX100, AX125and AX150diets were higher（P<0.05） than that of shrimp fed control diet. Hypoxia-inducible factor alpha (HIF^-1α),SOD and CAT mRNA expression levels of shrimp fed seven diets were significantlydown-regulated under hypoxia than under normoxia, but their expression levels werehigher under hypoxia in shrimp fed AX-supplemented diets than in shrimp fed controldiet.70-kDa heat-shock protein （Hsp70） mRNA expression level of shrimp fed sevendiets was significantly up-regulated under hypoxia than under normoxia, but itsexpression level was lower under hypoxia in shrimp fed AX-supplemented diets than inshrimp fed control diet. These results indicated that125mg kg^-1and150mg kg^-1AX-supplementation could improve growth, non-specific immune response andammonia stress resistance in juvenile L. vannamei.2. An8-week feeding trial and ammonia stress subsequently conducted to evaluatethe effects of dietary chitosan （CHS） on growth, non-specific immune response and stressresistance of juvenile Pacific white shrimp Litopenaeus vannamei. Seven diets with orwithout CHS supplementation namely Control （Basal feed （BF） without CHS）, CHS1.0(BF+1.0g CHS kg^-1diet), CHS2.0(BF+2.0g CHS kg^-1diet), CHS3.0(BF+3.0g CHSkg^-1diet), CHS4.0(BF+4.0g CHS kg^-1diet), CHS5.0(BF+5.0g CHS kg^-1diet) andCHS6.0(BF+6.0g CHS kg^-1diet) were fed to Litopenaeus vannamei （0.71±0.00g） for8weeks in35tanks （30shrimp per tank）. The results showed that shrimp fed allexperimental diets had no significant difference （P>0.05） on growth performance.However, shrimp fed CHS3.0diet had higher （P<0.05） phenoloxidase （PO） andlysozyme （LSZ） activities than shrimp fed control diet. After120mg L^-1ammonia stressfor72h, survival rate of shrimp fed CHS1.0, CHS3.0, CHS4.0, CHS5.0and CHS6.0diets were significantly higher （P<0.05） than that of shrimp fed control diet. These resultsindicated that although CHS-supplementation could not improve growth performance,3.0g kg^-1CHS-supplementation could enhance non-specific immune response andammonia stress resistance in juvenile L. vannamei.3. An8-week feeding trial and ammonia stress subsequently conducted to evaluatethe effects of dietary fructooligosaccharides （FOS） on growth, non-specific immune response and stress resistance of juvenile Pacific white shrimp Litopenaeus vannamei.Six diets with or without FOS supplementation namely Control （Basal feed （BF） withoutFOS）, FOS0.5(BF+0.5g FOS kg^-1diet), FOS1.0(BF+1.0g FOS kg^-1diet), FOS1.5(BF+1.5g FOS kg^-1diet), FOS2.0(BF+2.0g FOS kg^-1diet) and FOS2.5(BF+2.5g FOSkg^-1diet) were fed to Litopenaeus vannamei （0.60±0.00g） for8weeks in24tanks （30shrimp per tank）.The results showed that shrimp fed FOS0.5and FOS1.0diets had higher（P<0.05） WG, SGR, and lower （P<0.05） feed conversion ratio （FCR） than shrimp fedcontrol diet. Shrimp fed FOS2.0had lower （P<0.05） survival rate than shrimp fed controldiet. PO and alkaline phosphatase （AKP） activities of1.0g kg^-1FOS-supplementedgroup were significantly higher （P<0.05） than that of control group. Acid phosphatase（ACP） activity of1.0,1.5,2.0and2.5g kg^-1FOS-supplemented groups was significantlyhigher （P<0.05） than that of control group. After120mg L^-1ammonia stress for60h, allFOS-supplemented groups had significantly higher （P<0.05） survival rate than controlgroup. These results indicated that1.0g kg^-1FOS-supplementation could improve growth,non-specific immune response and ammonia stress resistance in juvenile L. vannamei.4. An8-week feeding trial and ammonia stress subsequently conducted to evaluatethe effects of dietary mannan oligosaccharide （MOS） on growth, gut morphology,non-specific immune response and stress resistance of juvenile Pacific white shrimpLitopenaeus vannamei. Six diets with or without MOS supplementation namely Control（Basal feed （BF） without MOS）, MOS12(BF+0.12g MOS kg^-1diet), MOS24(BF+0.24g MOS kg^-1diet), MOS48(BF+0.48g MOS kg^-1diet), MOS72(BF+0.72g MOS kg^-1diet) and MOS96(BF+0.96g MOS kg^-1diet) were fed to Litopenaeus vannamei （2.52±0.01g） for8weeks in36cement tanks （30shrimp per tank）.The results showed thatshrimp fed0.24,0.48,0.72and0.96g kg^-1MOS-supplemented diets had significantlyhigher （P<0.05） WG and SGR than shrimp fed control diet. Compared with control group,SEM and TEM analysis revealed that MOS-supplementation could significantly increase（P<0.05） the intestinal microvilli density and length of shrimp at the untrastructural level.After160mg L^-1ammonia stress for24h, survival rate of shrimp fed0.24,0.48,0.72and0.96g kg^-1MOS-supplemented diets was significantly higher （P<0.05） than that ofshrimp fed control diet. PO activity of0.48g kg^-1MOS-supplemented group was significantly higher （P<0.05） than that of control group under normal conditions, and POactivity significantly decreased （P<0.05） under ammonia stress than under normalconditions, but PO activity of0.48g kg^-1MOS-supplemented group was alsosignificantly higher （P<0.05） than that of control group under ammonia stress. SODactivity of0.48,0.72and0.96g kg^-1MOS-supplemented groups was significantly higher（P<0.05） than that of control group under normal conditions. These results indicated thatMOS supplementation could improve growth, gut morphology, non-specific immuneresponse and ammonia stress resistance in L. vannamei, and the0.24-0.48g kg^-1MOSsupplementation was suitable for L. vannamei.5. An8-week feeding trial and ammonia stress subsequently conducted to evaluatethe effects of dietary β-glucan on growth, non-specific immune response and stressresistance of juvenile Pacific white shrimp Litopenaeus vannamei. Seven diets withdifferent glucan-supplemental levels and feeding strategies namely Control （feedingβ-glucan-free diet continuously）, Treatment1(feeding dietary0.3g kg^-1β-glucancontinuously), Treatment2(feeding dietary0.6g kg^-1β-glucan continuously), Treatment3(feeding dietary0.9g kg^-1β-glucan continuously), Treatment4(feeding dietary0.3g kg^-1β-glucan discontinuously), Treatment5(feeding dietary0.6g kg^-1β-glucandiscontinuously) and Treatment6(feeding dietary0.9g kg^-1β-glucan discontinuously)were fed to Litopenaeus vannamei （1.00±0.00g） for8weeks in35tanks （30shrimp pertank）. The results showed that shrimp fed Treatment4, Treatment5and Treatment6dietshad higher （P<0.05） WG and SGR than shrimp fed control diet. PO, SOD, LSZ andLipopolysaccharide and β^-1,3-glucan binding protein （LGBP） mRNAs expression levelin hepatopancreas of Litopenaeus vannamei fed with all experimental diets wereexamined by real-time quantitative RT-PCR. PO mRNA expression level of shrimp fedTreatment5and Treatment6diets was significantly higher （P<0.05） than control diet.SOD mRNA expression level of shrimp fed all β-glucan diets was significantly higher（P<0.05） than control diet. There was no significant difference （P>0.05） of LSZ mRNAexpression level between β-glucan diets and control diet. LGBP mRNA expression levelof shrimp fed all β-glucan diets was significantly higher （P<0.05） than control diet,meanwhile, LGBP mRNA expression level of shrimp fed Treatment2, Treatment3, Treatment4, Treatment5and Treatment6was significantly higher （P<0.05） thanTreatment1. After160mg L^-1ammonia stress for24h, survival rate of shrimp fedTreatment4, Treatment5and Treatment6diets was significantly higher （P<0.05） than thatof shrimp fed control diet. PO activity of Treatment5and Treatment6was significantlyhigher （P<0.05） than that of control group under normal conditions, and PO activity ofall experimental groups significantly decreased （P<0.05） under ammonia stressconditions, but PO activity of Treatment6was also significantly higher （P<0.05） than thatof control group under ammonia stress conditions. SOD activity of Treatment5andTreatment6was significantly lower （P<0.05） than that of control group under normalconditions, and SOD activity of all experimental groups had no significant change（P>0.05） under ammonia stress conditions. LSZ activity of all experimental groups hadno significant difference （P>0.05） under normal conditions, but LSZ activity ofTreatment4, Treatment5and Treatment6was significantly increased （P<0.05） underammonia stress conditions. Moreover, LSZ activity of Treatment2, Treatment3,Treatment4, Treatment5and Treatment6groups was significantly higher （P<0.05） thanthat of control group under ammonia stress. These results indicated that feeding dietary0.3-0.9g kg^-1glucan-supplementation discontinuously could improve growth,non-specific immune response and ammonia stress resistance in L. vannamei.6. An8-week feeding trial and low dissolved oxygen stress subsequently conductedto evaluate the effects of dietary chitosan-Zn （CHS-Zn） on growth, non-specific immuneresponse and stress resistance of juvenile Pacific white shrimp Litopenaeus vannamei.Five diets namely Control （Basal feed （BF） without CHS-Zn）, CHS3000(BF+3000mgCHS kg^-1diet), CHS-Zn25(BF+25mg CHS-Zn kg^-1diet), CHS-Zn50(BF+50mgCHS-Zn kg^-1diet) and CHS-Zn100(BF+100mg CHS-Zn kg^-1diet) were fed toLitopenaeus vannamei （1.49±0.01g） for8weeks in25cement tanks （40shrimp pertank）. The results showed that shrimp fed all experimental diets had no significantdifference （P>0.05） on growth performance. However, shrimp fed3000mg kg^-1CHS and100mg kg^-1CHS-Zn diets had higher （P<0.05） PO and lysozyme LSZ activities thanshrimp fed control diet. SOD activity of all experimental groups had no significantdifference （P>0.05）. PO, SOD and LSZ mRNAs expression level in hepatopancreas of Litopenaeus vannamei fed with all experimental diets were examined by real-timequantitative RT-PCR. PO mRNA expression level of shrimp fed3000mg kg^-1CHS and100mg kg^-1CHS-Zn diets was significantly higher （P<0.05） than control diet. SODmRNA expression level of shrimp fed100mg kg^-1CHS-Zn diet was significantly higher（P<0.05） than control diet. LSZ mRNA expression level of shrimp fed3000mg kg^-1CHS,50mg kg^-1CHS-Zn and100mg kg^-1CHS-Zn diets was significantly higher （P<0.05）than control diet. After low dissolved oxygen stress for6h, survival rate of shrimp fedCHS-Zn100diet was significantly higher （P<0.05） than that of shrimp fed control diet.These results indicated that although CHS-Zn-supplementation could not improvegrowth performance,100mg kg^-1CHS-Zn-supplementation could enhance non-specificimmune response and low dissolve stress resistance in juvenile L. vannamei.更多还原