芽孢杆菌对草鱼生长和肠粘膜抗氧化功能及养殖水质的影响

本试验研究了饲料中添加芽孢杆菌对草鱼生长、肠粘膜抗氧化功能及养殖水体水质的影响。选取平均体重为（51.0±2.3）g的健康草鱼300尾,随机分成3组（对照组、处理组1和处理组2）,每组3个重复,每个重复50尾鱼。其中对照组饲喂基础日粮,处理组1和2分别饲喂含复合芽孢杆菌（105 cfu/克饲料,枯草芽孢杆菌和解淀粉芽孢杆菌以1:1比例混合）和枯草芽孢杆菌（105 cfu/克饲料）的基础日粮。试验期为45d。结果表明,饲料中添加芽孢杆菌对养殖水体pH和硝酸盐氮含量无显著影响,但显著降低了从第21d到试验结束期间水体中亚硝酸盐氮的含量（处理组1第35d除外）。芽孢杆菌的添加同时显著降低草鱼的死亡率（P<0.05）,并提高了草鱼的增重率和特定生长率。与对照组相比,处理组1和2草鱼的增重率分别提高了52.93%（P<0.01）和21.78%（P<0.05）,特定生长率分别提高了44.44%（P<0.01）和16.67%（P<0.05）;而且处理组1草鱼增重率和特定生长率分别比处理组2提高了25.58%（P<0.01）和23.81%（P<0.01）。肠粘膜抗氧化活性研究表明,与对照组相比,饲料中添加芽孢杆菌能提高草鱼肠粘膜超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性。以上结果提示,饲料中添加芽孢杆菌可以改善养殖水质和草鱼肠粘膜抗氧化功能,并显著促进草鱼生长并降低死亡率。     

饲料中添加复合芽孢杆菌对草鱼消化道酶活性及肠道菌群的影响

用含复合芽孢杆菌(105cfu/g饲料,枯草芽孢杆菌和解淀粉芽孢杆菌以1∶1比例混合)的基础日粮,按体重3%的日投饵量,饲喂体重(51.37±0.58)g的草鱼(Ctenopharyngodon idellus),饲养实验45 d。结果表明:与对照组相比,处理组肠道内容物胰蛋白酶活性提高了79.46%(P<0.01);肝胰腺脂肪酶活性提高了16.82%(P<0.01),肝胰腺淀粉酶和胰蛋白酶活性无显著差异(P>0.05)。肠道菌群数量分析显示,处理组肠道芽孢杆菌数均显著提高(P<0.01),弧菌和大肠杆菌数显著降低(P<0.01)。结果提示,饵料中添加复合芽孢杆菌能够改善草鱼肠道菌群组成,并提高消化道特定消化酶活性。     

饲料中添加谷胱甘肽对草鱼组织中谷胱甘肽沉积和抗氧化能力的影响

在基础饲料中分别添加还原型谷胱甘肽(GSH)至0 mg/kg、100 mg/kg、200 mg/kg、300 mg/kg、400 mg/kg和500 mg/kg,分别投喂草鱼(Ctenopharyngodon idella)幼鱼8周,草鱼幼鱼体质量(4.09±0.01)g,观察GSH在草鱼组织中沉积以及对草鱼抗氧化功能的影响.结果表明,饲料中添加外源GSH对草鱼生长影响不显著(P＞0.05),实验组肌肉中GSH含量显著高于对照组(P＜0.05),肝脏中GSH含量在GSH添加水平为200 mg/kg时显著高于对照组(P＜0.05),肝脏和肌肉中丙二醛(MDA)在GSH添加水平为300 mg/kg组达到最低,显著低于对照组(P＜0.05).添加GSH对血清中GSH和MDA影响不显著(P＞0.05).草鱼肝脏中谷胱甘肽还原酶(GR)活力在400 mg/kg组显著高于对照组(P＜0.05),肌肉中GR活力有增高趋势但差异不显著(P＞0.05);肝脏和肌肉中γ-谷氨酰转移酶(γ-GT)均高于对照组,分别在300 mg/kg组和200 mg/kg组达到显著水平(P＜0.05);肝脏中谷胱甘肽过氧化物酶(GSH-PX)活力、总抗氧化能力(T-AOC)和超氧化物歧化酶(SOD)能力不同程度升高,均在200 mg/kg组达到最高,显著高于对照组(P＜0.05);血清GSH-PX活力和T-AOC有增高趋势但与对照组差异不显著(P＞0.05);血清和肝脏中活性氧(ROS)含量分别在400 mg/kg和300 mg/kg组达到最低,显著低于对照组(P＜0.05).结果提示,饲料中添加GSH能够促进草鱼肝脏和肌肉中GSH的沉积,提高肝脏及肌肉中GR和γ-GT活力,以及肝脏中GSH-PX和SOD活力与总抗氧化能力,减少肝脏中MDA含量,降低肝脏及血清中ROS含量,因此GSH在水产饲料中具有广泛的应用前景.     

小球藻对草鱼生长、免疫、消化酶活性和肌肉的影响

为探明饲料中添加不同水平的小球藻对草鱼生长性能、非特异性免疫机能、消化酶活性及肌肉品质的影响,选用平均体质量(105.92±2.79) g的草鱼随机分为5个组,每组30尾,分别投喂添加小球藻为0(对照组)、0.25%、0.50%、0.75%和1.00%的试验饲料,饲养周期为28 d。试验结果显示,0.50%、0.75%和1.00%添加组的终末平均体质量、质量增加率和特定生长率均显著高于对照组(P<0.05),饲料系数均显著低于对照组(P<0.05)。当添加量达0.75%时,能显著提高草鱼血清的溶菌酶和碱性磷酸酶的活性,增强草鱼的非特异性免疫机能(P<0.05)。各添加组血清中超氧化物歧化酶活性和抗氧化能力(除0.25%添加组)显著提高。各添加组草鱼脂肪酶和胰蛋白酶活性明显升高,淀粉酶(除0.25%添加组)活性显著减弱(P<0.05)。添加组草鱼肌肉的氨基酸组成与对照组无显著差异(P>0.05)。1.00%添加组的草鱼肌肉中亚麻酸和二十碳五烯酸含量显著高于对照组(P<0.05),0.25%、0.75%和1.00%添加组的花生四烯酸和二十二碳六烯酸含量显...     

微生态制剂对草鱼生产性能和肠道菌群的影响

在水温25~30℃下,将体质量为(110.23±0.43)g的草鱼饲养在3.0 m×2.0 m×1.2 m的加盖网箱中,分别投喂添加0%(对照组)、0.5%和2%的由芽孢杆菌、乳酸菌以及酵母菌复配且以麸皮为载体制成的微生态制剂(8.0×10~9 cfu/g)的膨化饲料饲养60 d,探究微生态制剂对草鱼生产性能和肠结构、菌群及酶活性的影响。试验结果显示,饲料中添加2%微生态制剂显著提高草鱼质量增加率、特定生长率(P<0.05),显著降低饲料系数、脏体比(P<0.05);饲料中添加2%微生态制显著提高肠伸展率、中肠肌层厚度和绒毛高度(P<0.05),提高中肠淀粉酶和脂肪酶活性(P<0.05)。饲料中添加微生态制剂增加草鱼肠道菌群α多样性、丰富度;改变草鱼肠道微生物组成,门水平上,对照组的草鱼肠道微生物中梭杆菌门和厚壁菌门含量最高(63.56%、32.52%)。0.5%添加组的草鱼肠道微生物中梭杆菌门和厚壁菌门含量最高(61.82%、20.27%)。2%添加组的草鱼肠道微生物中厚壁菌门含量最高(64.20%)。属水平上,2%添加组草鱼肠道优势菌属直接发生改变,Paeniclostridium和Erysipelatoclostridium丰度大幅上升。随着微生态制剂添加量的增加,肠道微生物的代谢功能增强,组成中与无机离子转运和代谢、碳水化合物转运与代谢、氨基酸转运与代谢等功能相关的菌群丰度升高。综上可知,饲料中添加芽孢杆菌、乳酸菌以及酵母菌等组成的微生物制剂可作为生产草鱼绿色饲料的重要措施。     

酵母培养物和芽孢杆菌对凡纳滨对虾生长、蛋白酶活性和免疫性能的影响

研究了饲料中添加酵母培养物(益康XP)和芽孢杆菌(Bacillus)制剂对凡纳滨对虾(Litopenaeusvannamei)生长、肌肉成分、蛋白酶活性和免疫功能的影响。在基础饲料(对照组)中分别添加0.075%益康XP、0.100%益康XP、0.200%芽孢杆菌,饲养均重(5.57±0.21)g的凡纳滨对虾45 d。结果表明,添加0.075%益康XP、0.100%益康XP、0.200%芽孢杆菌分别提高凡纳滨对虾增重率17.24%、12.29%、20.18%,降低饲料系数14.28%、9.77%、12.03%,提高蛋白质效率16.49%、10.05%、12.98%(P<0.05);添加酵母培养物和芽孢杆菌对凡纳滨对虾肌肉组成成分没有影响(P>0.05);0.075%益康XP组、0.100%益康XP组、0.200%芽孢杆菌组肝胰脏蛋白酶活性较对照组分别提高25.24%、15.22%、54.92%(P<0.05);各试验组肠蛋白酶活性与对照组相比有所提高,但均未达到显著水平(P>0.05);0.100%益康XP、0.200%芽孢杆菌组凡纳滨对虾血清酚氧化酶活性、溶菌酶活性和超氧化物歧化酶活性均显著高于对照组(P<0.05);攻毒实验表明,感染溶藻弧菌后,芽孢杆菌组对虾第1、3、4天的累积死亡率均显著低于对照组(P<0.05),第4天时的免疫保护率达到27.1%,而添加益康XP对累积死亡率无显著影响(P>0.05)。综上所述,饲料中添加酵母培养物益康XP和芽孢杆菌均能改善凡纳滨对虾生长性能和消化功能,芽孢杆菌能增强凡纳滨对虾对溶藻弧菌的抗感染功能。     

蜡样芽孢杆菌对银鲑生长性能、血清生理生化指标、肝脏抗氧化能力及肠道的组织结构影响

在水温10～18℃下,将初始体质量(130.2±10.5)g的银鲑(Oncorhynchus kisutch)饲养在流水水泥池中1×1×0.8(m3)的网箱中,每箱20尾,投喂喷淋活蜡样芽孢杆菌(Bacillus cereus)菌液的饲料,添加量分别为0 CFU/g(CK对照组)、8×10¹¹CFU/g(H组)、4×10⁹CFU/g(M组)和2×10⁷CFU/g(L组)6周,每组设3个重复,研究饲料中添加不同浓度的蜡样芽孢杆菌对银鲑生长性能、血清生理生化指标、肝脏抗氧化能力以及肠道组织结构的影响。结果表明,投喂添加蜡样芽孢杆菌饲料的银鲑增重率(WGR)、肝体比(HSI)、存活率(SR)和特定生长率(SGR)均显著高于对照组(P<0.05),饲料系数(FCR)显著降低(P<0.05),蛋白质效率(PER)显著提高(P<0.05);各试验组银鲑血清中总胆固醇(T-CHO)、血清葡萄糖(GLU)、血清总蛋白(TP)含量与血清白蛋白(ALB)含量均显著提高(P<0.05)。其中,蜡样芽孢杆菌M组CHO、G...     

地衣芽孢杆菌对大泷六线鱼生长、肠道消化酶、血清非特异性免疫及抗病力的影响

本研究探讨饲料中添加地衣芽孢杆菌(Bacillus licheniformis)对大泷六线鱼(Hexagrammos otakii)生长、肠道消化酶、血清非特异性免疫及抗病力的影响。选取平均体重为(22.0±2.0) g的大泷六线鱼270尾,随机分成3组(对照组和2个不同菌剂水平的实验组),每组3个平行,每个平行 30尾鱼。对照组投喂仅有蛋白液包裹的基础饲料,实验组投喂含活菌量达5×107 CFU/g(0.5%)和1×108 CFU/g(1.0%)地衣芽孢杆菌的实验饲料。投喂50 d后进行致病菌杀鲑气单胞菌(Aeromonas salraonicida)攻毒感染,测定14 d内累积死亡率。结果显示,实验组饲料中地衣芽孢杆菌可显著提高大泷六线鱼的特定生长率(SGR) (P<0.05)。与对照组比较,0.5%和1.0%地衣芽孢杆菌均可提高大泷六线鱼血清中SOD、CAT及T-AOC活性(P<0.05),降低MDA含量(P<0.05);GSH-Px活性在1.0%实验组较对照组下降,而0.5%实验组较对照组提高。地衣芽孢杆菌实验组鱼血清GS、MDH和HK活性均得到提高(P<0.05),0.5%和1.0%不同剂量组的提高程度不同。地衣芽孢杆菌实验组鱼血清中AST和ALT活性较对照组均降低(P<0.05),CHE和ADA活性较对照组有提高(P<0.05)。实验组鱼肠道胰蛋白酶、淀粉酶和脂肪酶活性均有不同程度的提高,且1.0%实验组活性最强(P<0.05)。攻毒实验结果显示,1.0%地衣芽孢杆菌组大泷六线鱼14 d内累积死亡率仅有35.55% (P<0.05)。由此可见,饲料中添加地衣芽孢杆菌可促进大泷六线鱼生长,提高其肠道消化酶活性及非特异性免疫酶活性,增强其对杀鲑气单胞菌的抵抗能力。     

皇竹草粉对草鱼幼鱼生长、抗氧化反应和肠道健康的影响

为评估皇竹草(Pennisetum sinese Roxb)粉对草鱼(Ctenopharyngodon idellus)幼鱼生长、抗氧化和肠道健康的影响,配制3组分别含0% (对照组C)、10%和20%皇竹草粉(P1和P2)的等氮等能半精制饲料(蛋白质水平为36%,脂肪水平为9%),饲喂草鱼稚鱼[(28.51±0.04) g] 56 d。结果显示,相比C组,P1和P2组显著提高了草鱼幼鱼的增重率和成活率(P<0.05);P2组草鱼血清丙二醛(MDA)含量比C组草鱼显著降低(P<0.05);P1和P2组草鱼血清中谷草转氨酶(AST)和谷丙转氨酶(ALT)活性比C组草鱼显著降低(P<0.05);P1和P2组的草鱼血清中补体C3和C4的含量显著提高(P<0.05);同时,这2组肝脏的3-羟酰辅酶A脱氢酶(HOAD)和细胞色素C氧化酶(COX)的活性也显著高于C组(P<0.05);肠道显微结构显示,P1和P2组显著提高了草鱼幼鱼肠道的绒毛高度和皱褶深度,降低了肌层厚度(P<0.05);基因表达层面,相比C组,P1和P2组下调了肠道促炎细胞因子肿瘤坏死因子α (tnf-α)和白细胞介素1β (il-1β)的基因相对表达量。综上所述,饲料中添加一定量的皇竹草粉能增强草鱼幼鱼的生长,降低体内氧化应激和肠道炎症。     

饲料中添加枯草芽孢杆菌对拟穴青蟹幼蟹生长性能、消化酶活性和体成分的影响

为探讨饲料中添加不同含量枯草芽孢杆菌对拟穴青蟹(Scylla paramamosain)幼蟹生长、消化酶活性及体成分的影响,以初始体质量为(25.74±0.51)mg的拟穴青蟹Ⅰ期仔蟹为试验对象,在基础饲料中分别添加0、0.1%和0.5%的枯草芽孢杆菌制成3种试验饲料,饲喂幼蟹3周。试验结果:添加枯草芽孢杆菌的组,拟穴青蟹幼蟹的终末平均体质量、体质量增长率、特定生长率和蛋白酶活性显著高于对照组(P<0.05),但两个不同添加量试验组间的差异不显著(P>0.05);添加枯草芽孢杆菌显著增强了幼蟹蛋白酶和淀粉酶的活性(P<0.05),对幼蟹的水分、粗蛋白和灰分含量均没有显著影响(P>0.05);添加0.5%枯草芽孢杆菌的试验组,幼蟹的脂肪含量显著高于其它试验组(P<0.05)。结果表明,在本试验条件下,饲料中添加枯草芽孢杆菌对拟穴青蟹幼蟹的生长有显著促进作用,对蛋白酶活性、淀粉酶活性和体粗脂肪含量也有显著影响,添加0.1%～0.5%的枯草芽孢杆菌对拟穴青蟹幼蟹有较好的促生长效果。     

Identification of SNPs in the 5′‐flanking region and 3′‐UTR of the MIH gene and their association with precocity of the Chinese mitten crab Eriocheir sinensis

Moult‐inhibiting hormone (MIH), an important regulator of steroidogenesis, inhibits the synthesis of ecdysteroid in Y‐organ (YO) and plays a significant role in the regulation of moulting and post‐embryonic development of crustacean. Because unsuccessful moulting have been widely observed in precocious crabs, we investigated whether genetic variants in the 5′‐flanking region and 3′‐untranslated region (3′‐UTR) of the MIH gene are associated with precocity of the Chinese mitten crab. Thirty individual DNA samples were sequenced to search for SNPs in the 5′‐flanking region and 3′‐UTR of the MIH gene. Five SNPs (g.196 T>A, g.230 C>T, g.305 T>C, g.323 C>A and g.372 C>T) in the 5′‐flanking region and 6 SNPs (g.2677 C>T, g.2759 T>A, g.2807 T>C, g.3042 A>G, g.3088 T>G and g.3295 T>G) in the 3′‐UTR of the MIH gene were selected for the individual genotyping in a two‐stage association study. We found that a SNP g.3088 T>G in the 3′‐UTR of MIH gene was consistently associated with precocity of the Chinese mitten crab in stage 1 and stage 2, with a per‐allele OR (Odds Ratio) of 1.469 (95% CI: 1.169–1.844) after two stages combined (P = 0.001). However, no significant associations were observed between the other 10 SNPs and precocity of the Chinese mitten crab. To our best knowledge, this is the first association study between various SNP genotypes and phenotype attributes in Chinese mitten crab. Our findings suggest that the SNP g.3088 T>G may be a candidate marker for effective marker‐assisted selection to decrease the precocity of the Chinese mitten crab in future studies.     

Haemato-biochemical,non-specific immunity,antioxidant capacity and histopathological changes in <Emphasis Type="Italic">Labeo rohita</Emphasis> fingerlings fed rubber protein isolate

A 60-day feeding trial was conducted to evaluate the haemato-biochemical, innate immune response, antioxidant capacity and histopathological changes in Labeo rohita fingerlings fed rubber protein isolates (RPI). One hundred and eighty fingerlings (average weight 4.45 ± 0.01 g) were distributed into five experimental groups in triplicate and fed with isonitrogenous and isocaloric diets. Soybean protein isolate (SPI) served as the reference diet (Control), and the treatment diets were formulated as RPI₂₅, RPI₅₀, RPI₇₅ and RPI₁₀₀ replacing 25, 50, 75 and 100% of SPI protein, respectively. The growth performance indices like final body weight (9.54–10.27 g), net weight gain (5.09–5.84 g), metabolic growth rate (4.54–5.02) and feed efficiency ratio (0.60–0.65) among the various groups were not significantly different (P > 0.05). All the haematological parameters, except red blood cells, showed no significant differences compared with the control group (P > 0.05). The immuno-biochemical parameters like albumin, globulin, total immunoglobulin, respiratory burst and lysozyme activities among the various groups did not differ significantly (P > 0.05). The stress enzyme such as superoxide dismutase (SOD), catalase (CAT) and oxidative stress marker malondialdehyde (MDA) showed no significant difference (P > 0.05). Histopathological examination of the liver revealed no marked changes. In summary, the results showed that RPI was well utilised by the fish and its inclusion did not generate any oxidative-induced stress, thus, RPI may be suggested as a potential replacement for SPI in fish diets without any detrimental effects. Hence, protein isolation offers a unique opportunity for the utilisation of rubber seed meal.     

The study of some haematological and serum biochemical parameters of juvenile beluga (<Emphasis Type="Italic">Huso huso</Emphasis>) fed oligofructose

A study was conducted to investigate the effects of dietary oligofructose (1, 2 and 3%) on the blood profiles of beluga (Huso huso) juveniles (18.77 ± 0.76 g) compared to fish fed an un-supplemented diet. After 7 weeks of feeding on the experimental diets, haematological parameters, metabolic products (cholesterol, glucose and total protein) and serum enzymes (lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) were measured. Compared to the control group (0% oligofructose), dietary oligofructose had no effect on red blood cell counts (RBC), mean corpuscular volume (MCV), mean cellular haemoglobin (MCH) or mean cell haemoglobin concentration (MCHC) (P > 0.05). However, haemoglobin (Hb) concentration, leucocyte (WBC) levels and the proportion of lymphocytes were significantly higher (P > 0.05) in the 2% oligofructose fed fish than in the 3% oligofructose fed fish. Additionally, haematocrit (Hct) values (P = 0.049) and the proportion of lymphocytes (P ≤ 0.01) were significantly higher in the 2% oligofructose group than in the control group. Although serum glucose and total protein remained unaffected, serum cholesterol was significantly lower in the 2% oligofructose group than in the control and 3% oligofructose group (P < 0.05). The results of the present study showed that oligofructose had no significant effects on serum lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. These results indicate that fish blood profiles could be affected by prebiotics, which should be taken into account in future studies.     

Dietary myo‐inositol requirements of juvenile hybrid sturgeon (Acipenser baerii ♀ × A. schrenckii ♂)

This study was conducted to determine the optimal dietary myo‐inositol (MI) requirement of juvenile hybrid sturgeon (Acipenser baerii ♀ × A. schrenckii ♂). Fish with an initial average body weight of 28.28 ± 0.41 g were randomly divided into six groups with three repetitions in each group and fed the experimental diets with different graded MI concentrations (70.2, 130.0, 270.2, 443.0, 1,096.6 and 1997.3 mg/kg) three times per day for 12 weeks. The results showed that with the increase in dietary MI level from 70.2 mg/kg to 443.0 mg/kg, weight gain (WG) was increased significantly (p < .05); however, when the MI level was further increased, there was no significant difference in weight gain rate (WG) over time (p > .05). Specific growth rate (SGR) showed a similar trend. The feed conversion ratio (FCR), survival rate (SR), hepatosomatic index (HSI), viscerasomatic index (VSI) and condition factor (CF) were not affected by dietary MI supplementation (p > .05). Dietary MI did not affect whole‐body and muscle crude protein and ash content (p > .05), while dietary MI significantly affected the muscle and whole‐body crude lipid and moisture content (p < .05). Moreover, serum triglyceride (TG), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were decreased by increasing dietary MI levels. Total antioxidant capacity (T‐AOC), malonic dialdehyde (MDA) and superoxide dismutase (SOD) activities in the liver were also affected by the dietary MI (p < .05). In summary, this study indicated that the optimal dietary MI requirement for juvenile hybrid sturgeon (Acipenser baerii ♀ × A. schrenckii ♂) was 335.84 mg/kg and 590.65 mg/kg based on the maximum WG and liver MI accumulation indices respectively.     

不同饲料投喂模式对脊尾白虾生长、消化酶、体成分及养殖水环境的影响

为研究池塘多元养殖模式下不同饲料投喂模式对脊尾白虾（）生长、消化酶活性、体成分及养殖水环境的影响，实验以脊尾白虾及其养殖水为研究对象，设置3个实验组，分别为投喂冰鲜饲料组（Diet1组）、投喂配合饲料组（Diet3组）及两者1：1混合投喂组（Diet2组）。每个实验组设3个重复，实验周期为45 d，实验每隔5 d测脊尾白虾体重和养殖水质指标并分析；实验结束时，采集脊尾白虾样品，用于消化酶及体成分的测定与分析。结果显示：（1）不同饲料投喂30 d后，Diet2组脊尾白虾的体重显著高于Diet1组和Diet3组（>0.05）；增重率与特定生长率随时间呈下降趋势。（2）从Diet1组至Diet3组饲料中蛋白水平逐渐降低，而脊尾白虾蛋白酶活性逐渐降低，淀粉酶活性逐渐提高；各实验组脂肪酶活性差异不显著（P>0.05）。Diet2组脊尾白虾水分含量显著低于Diet1组和Diet3组（>0.05）。（4）随着实验的进行，脊尾白虾养殖水环境中COD、氨氮、亚硝酸盐、硝酸盐、无机氮及无机磷均呈上升趋势，实验结束时，各水质指标由高到低依次为Diet1组、Diet2组、Diet3组。因此，池塘多元养殖模式下混合投喂"冰鲜饲料+人工配合饲料"，有利于脊尾白虾的生长、消化及蛋白积累，然而对养殖水环境仍存在一定的污染，研制环保型人工配合饲料仍是大势所趋。     

秦皇岛海域赤潮期间浮游植物的生态特征

2010年5月下旬,秦皇岛海域暴发了多次赤潮,其影响一直持续至当年的8月份。通过2010年5–9月对秦皇岛近岸海域进行的5个月份调查,对赤潮期间该海域浮游植物的种类组成、时空分布、群落结构特征及浮游植物与夜光藻的依存关系、浮游植物与环境因子的关系进行了分析。结果表明,调查海域共检出浮游植物46属96种,主要隶属硅藻门(Bacillario phyta)和甲藻门(Pyrroptata),生态类型多数为广温广盐的广布种或近岸性种类,少数为暖海性物种或远洋性种类。主要优势种有夜光藻(Noctiluca scintillans)、斯托根管藻(Rhizosolenia stolterfothii)、角毛藻(Chaetoceros sp.)、圆筛藻(Coscinodiscus sp.)和辐杆藻(Bacteriastrum sp.)等。共鉴定赤潮生物48种,占浮游植物种类数的50%。浮游植物丰度均值的变化范围为6.20×104~4 129.53×104 cells/m3,其丰度均值的高峰出现在9月份,低谷出现在7月份。调查海域浮游植物5个月份的多样性指数均值都大于1,生物多样性状况良好,群落结构比较稳定;聚类分析表明,5个调查月份群落相似性程度较高,相似性范围为40%~71%。相关性分析表明,浮游植物平均丰度与盐度存在显著的负相关关系(r=–0.734,P0.01,N=37);与无机氮营养盐(DIN)存在显著地正相关关系(r=0.753,P0.01,N=37),推测调查期间该海域浮游植物生长繁殖的主导环境因子为无机氮营养盐。浮游植物物种与环境因子的典范对应分析表明,N/P、盐度、硝酸盐、硅酸盐、亚硝酸盐和水温是影响秦皇岛海域浮游植物群落结构特征的主要环境因子。     

不同比例复合益生菌对凡纳滨对虾生长、免疫及抗氨氮能力的影响

对从凡纳滨对虾(Litopenaeus vannamei)肠道中分离出的鲍鱼希瓦氏菌(Shewanella haliotis)、蜡样芽孢杆菌(Bacillus cereus)和双壳气单胞菌(Aeromonas bivalvium)3株有益菌株,利用正交设计得到9种复合比例,通过饲料中添加上述9种比例混合的菌体(菌数总量为109 cfu/g)饲喂凡纳滨对虾,经过28 d养殖实验,评价其对凡纳滨对虾生长、免疫指标的影响。随后,利用氯化铵调节水体氨氮浓度至26.67 mg/L,经过16 d的氨氮毒性实验,研究不同比例复合益生菌对凡纳滨对虾抗氨氮能力的影响。研究结果表明,9个复合益生菌实验组的增重率和特定生长率均显著高于对照组(P0.05),并且以3株菌菌数6︰1︰3比例效果较好;不同配比的复合益生菌能够显著提高酸性磷酸酶(ACP)、碱性磷酸酶(ALP)、总超氧化物歧化酶(T-SOD)活力(P0.05),并表现出了不同的影响效果,其中,3株菌菌数(菌数总量为109 cfu/g,下同)2︰3︰3、4︰2︰3及6︰1︰3比例对ACP活力具有显著促进作用(P0.05),3株菌菌数4:2︰3和6︰1︰3比例对ALP活力具有显著促进作用(P0.05);3株菌菌数2︰1︰1比例对T-SOD活力具有显著促进作用(P0.05);各比例的复合菌对溶菌酶活力的影响不显著(P0.05);氨氮浓度26.67 mg/L条件下,不同比例复合菌组对虾累计存活率显著高于对照组(P0.05),其中以3株菌菌数4︰3︰1和6︰3︰2比例组累计存活率较高,即抗氨氮效果较好。     

Effects of triploidy on the Caspian salmon <Emphasis Type="Italic">Salmo trutta caspius</Emphasis> haematology

The aim of this study was a comparison of key haematological features of diploid (2n) and triploid (3n) Caspian salmon (Salmo trutta caspius). Morphometric indices of erythrocytes were determined on blood smears by light microscopy. Triploidy significantly (P < 0.001) increased all morphometric indices measured in the erythrocytes including cell size, cell surface area, and cell volume. The increase in cell size was larger for the major (27%) axis than for the minor (22%) axis, thus making erythrocytes of 3n Caspian salmon more ellipsoidal. The estimated increase in erythrocyte nuclear volume (87%) was bigger than the theoretical expected 50% increase. Haematological indices were measured manually by hemocytometry. Triploids had lower numbers of red blood cells (RBC: 1,120,000 cells/mL in 2n vs. 700,000 cells/mL in 3n; P < 0.001) but they were larger in size (mean erythrocytic volume [MEV]: 363.1 nm³ in 2n vs. 483.3 nm³ in 3n; P < 0.001). The decrease in RBC number was not compensated by the increase in MEV and, thus, triploidy affected the haematocrit (Hct: 38.8% in 2n vs. 33.06% in 3n; P < 0.05). Total blood hemoglobin concentration was lower in triploid fish (Hb: 9.9 g/dL in 2n vs. 8.9 g/dL in 3n; P < 0.05). In contrast, mean erythrocytic hemoglobin (MEH: 95 μg in 2n vs. 133.2 μg in 3n; P < 0.001) was higher for 3n Caspian salmon as a result of their larger erythrocytes, although MEH concentration (MEHC: 0.26 g/dL in 2n vs. 0.27 g/dL in 3n) did not significantly differ (P > 0.05). White blood cell (WBC) counts (lymphocytes and neutrophiles) were measured and WBC/RBC ratios were calculated. There were no significant differences in WBC (15,710 cells/mL in 2n vs. 12,683 cells/mL in 3n; P > 0.05), lymphocytes, and neutrophils as %WBC as well as WBC/RBC ratios between two ploidy levels (P > 0.05). Triploid Caspian salmon showed higher erythrocyte abnormalities such as ‘twisted’, ‘tailed’, and ‘anucleated’ cells as well as high portions of immature RBC in blood smears in comparison with diploids (P < 0.001).