混合蛋白源替代鱼粉对花鲈(Lateolabrax maculatus)生长性能、血浆生化指标和肝脏健康的影响

为研究混合蛋白源(酶解猪血球蛋白粉、豆粕和玉米蛋白粉)替代鱼粉对花鲈生长性能、血浆生化指标和肝脏健康的影响,配制6组等氮等脂(粗蛋白约为45%、粗脂肪约为8%)饲料,以30%的鱼粉作为对照组(RF0组),在对照组基础上分别用混合蛋白源替代2.5%、5.0%、7.5%、10.0%和12.5%的鱼粉,分别记为RF1、RF2、RF3、RF4组和RF5组,分别投喂6组花鲈[初始均重(11.40±0.15)g],养殖周期56 d。结果显示:①RF1组末均重、特定生长率、增重率、溶菌酶和碱性磷酸酶活性显著高于其他各组(P<0.05),总抗氧化能力、过氧化氢酶和谷胱甘肽过氧化物酶活性显著高于RF0组(P<0.05);②随着混合蛋白源替代鱼粉比例升高,肝体比、脏体比、肥满度、谷草转氨酶、谷丙转氨酶、微量还原型谷胱甘肽、谷胱甘肽过氧化物酶和谷胱甘肽S-转移酶活性呈上升趋势,而高密度脂蛋白胆固醇呈下降趋势;③RF1、RF2和RF3组试验鱼肝脏切片相比于其他各组,脂质空泡明显改善,肝细胞结构清晰。研究表明,混合蛋白源替代2.5%的鱼粉可提高花鲈的生长性能、增强抗氧化能力、改善其免疫状态和肝脏脂质空泡化。

美国红鱼(Sciaenops ocellatus)、鲈鱼(Lateolabrax maculatus)、斜带髭鲷(Hapalogenys nitens)耐流性试验研究

采用续航游泳时间评测指标作为评测鱼类游泳能力的方法,对一龄美国红鱼、鲈鱼、斜带髭鲷的续航时间,美国红鱼的临界(游泳)速度以及水温对美国红鱼续航时间影响进行了初步研究。结果表明,三种鱼中,美国红鱼耐流能力最强,其次为鲈鱼和斜带髭鲷。美国红鱼、鲈鱼、斜带髭鲷三种鱼的续航时间(或续航能力)与水流流速呈乘幂递减关系。水温对美国红鱼的游泳能力有显著的影响,试验结果表明,本文研究的美国红鱼,在水温20℃、流速84cm/s下的持续续航时间最长,可认为是该规格美国红鱼最适游泳水温范围。

盐度调控对花鲈(Lateolabrax maculatus)生长相关基因表达的影响

生长激素受体(GHR)作为GH/IGF轴的中心环节,在内分泌调控中发挥重要作用。本实验采用c DNA末端快速扩增法(RACE)技术克隆出花鲈GHR1和GHR2的c DNA全长序列。急性低盐度调控实验设为海水组、半海水组和淡水组。测定了急性低盐度调控24、48、96、144、192h后,花鲈肝脏中GHRs、IGF-1及垂体GH表达情况。结果表明,GHR1 c DNA全长序列2436bp,编码637个氨基酸;GHR2 c DNA全长序列2940bp,编码582个氨基酸。GHR1与GHR2由信号肽、胞外区、跨膜区、胞内区组成,且结构存在差异。脑、肾、鳃中GHR1表达明显高于GHR2;而在肌肉、垂体、肝脏、盲肠、胸腺、心脏中,GHR2表达明显高于GHR1。24h时,各组GHR1表达不变,GHR2、GH、IGF-1显著下降。之后,相对于海水组,淡水组和半海水组GHRs和IGF-1表达升高,而GH下降,GH与GHR负相关。据结果推测,花鲈GHR2可能为SL受体,GH/IGF轴参与低渗调控可能是通过增加GHRs,进而激活下游IGF-1表达而实现。

养殖花鲈(Lateolabrax maculatus)肠道菌群的多样性分析

为探究养殖花鲈(Lateolabrax maculatus)肠道菌群的结构特征,采用Illumina Hiseq2500高通量测序技术,对福建宁德三都澳网箱养殖花鲈的肠道内容物及肠壁菌群16S rDNA V3-V4区进行测序。肠道内容物和肠壁样品分别获得456和293个OTUs(operational taxonomic units),分属22个门120个属。花鲈肠道菌群以厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和梭杆菌门(Fusobacteria)细菌为主要优势菌群,分别占其肠道菌群数量的47.2%、25.8%、14.4%和10.3%。在属分类水平上,发光杆菌属(Photobacterium)、梭菌属(Clostridium)及鲸杆菌属(Cetobacterium)等属细菌是主要类别。对养殖花鲈的肠道内容物与肠壁菌群进行比较分析显示,肠壁菌群多样性略高于肠道内容物。肠道内容物中,发光杆菌属、梭菌属及鲸杆菌属等是主要菌属,其中鲸杆菌属和梭菌属分别占肠道内容物菌群总菌数的17.8%和12.5%,为主要标志性差异种类;在肠壁样品的菌群中,乳球菌属(Lactococcus)、真杆菌属(Eubacterium)、Lachnoclostridium、弓形菌属(Arcobacter)和Flavonifractor为丰度较高的菌属,其中格氏乳球菌(Lactococcus garvieae)为主要标志性物种,占肠壁菌群总数的5.6%。在花鲈肠壁上定殖着格氏乳球菌(L.garvieae)和美人鱼发光杆菌(Photobacterium damselae subsp.damselae)等条件致病菌,因此,在养殖中需要注重饵料及环境的管理,避免致病菌大量增殖引起暴发性鱼病。

Spotted Sea Bass(Lateolabrax maculatus) cftr, nkcc1a, nkcc1b and nkcc2: Genome-Wide Identification, Characterization and Expression Analysis Under Salinity Stress

The Na^+/K^+/2Cl^-cotransporter(NKCC)and the cystic fibrosis transmembrane conductance regulator(CFTR)proteins play crucial roles in the transportation of Na^+and Cl^-.In this study,we identified cftr,nkcc1 a,nkcc1 b and nkcc2 in spotted sea bass(Lateolabrax maculatus)genomic and transcriptomic databases.We also characterized these genes via phylogenetic and structural analyses.The results showed that both cftr and nkcc were highly conservative in L.maculatus.Quantitative real-time polymerase chain reaction(qRT-PCR)analysis in ten tissues showed that cftr,nkcc1 a and nkcc2 highly express in osmoregulatory organs such as gill,kidney and intestine.Furthermore,the expressions of cftr and nkcc1 a in gill as well as nkcc2 in intestine were up-regulated by high salinity,indicating that these genes function potentially in osmoregulation.Our findings provided the insights into the cftr and nkcc functions in euryhaline teleost.

Isolation of CYP17 Ⅰ, 3β-HSD and AR Genes from Spotted Sea Bass (Lateolabrax maculatus) Testis and Their Responses to Hormones and Salinity Stimulations

In this study, three cDNA sequences corresponding to cytochrome P450 C17(CYP17 Ⅰ), 3β-hydroxysteroid dehydrogenase(3β-HSD) and androgen receptor(AR) were isolated from spotted sea bass(Lateolabrax maculatus). The mRNA abundances of CYP17 Ⅰ and 3β-HSD increased from stage Ⅱ to stage V with a significant increase at stage Ⅴ, and the highest abundance of AR mRNA was detected at stage Ⅲ in testicular development cycle. CYP17 I, 3β-HSD and AR transcripts were obviously abundant in steroidogenesis tissues such as testis, brain, head kidney among others. Strong and positive signals were observed mainly in interstitial cell regions of L. maculatus testis as were measured with in situ hybridization method. Significant increases of CYP17 Ⅰ and3β-HSD transcripts were detected after 12-48 h hCG(human chorionic gonadotropin) and GnRHa(gonadotropin-releasing hormone analogue) treatments. However, an opposite relationship was found for AR in testis at the same time. In addition, decreasing trends of CYP17 Ⅰ and 3β-HSD mRNA were observed in testis of L. maculatus in freshwater group(FW) from day 2 to day 6, and mRNA abundance of AR increased in brackish water(BW) group from day 4 to day 8. These findings revealed that these three steroid synthesis genes are import for testicular development, hormone and salinity treatment, and provided also an insight into the mechanism of reproductive endocrine of L. maculatus.

Effects of Three Plant Powders on Behaviour, Mortality and Reproductive Fitness of Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)

The effects of powders from dry flower buds of Eugenia aromatica Baill., seeds of Piper guineense Schum and Thonn and fruits of Capsicum frutescens L. on adult behaviour, mortality and reproductive fitness of the cowpea seed beetle, Callosobruchus maculatus (Fab.) were investigated under ambient laboratory conditions. All experiments were carried out in glass Petri plates. All powders elicited aversion in adult beetles. The contact toxicity symptoms included restlessness, loss of coordination, knock down and eventual death of adult beetles. These behaviours were more pronounced with E. aromatica in which adult beetles died within 16 hours. P. guineense and C. frutescens powders did not cause 100% mortality of adult beetles, even after 24 hours. Each of the three powders significantly (P<0.05) reduced the mating competition of adult males after sub-lethal exposure for one, two, and three hours, respectively. E. aromatica powder caused more reduction in male mating competition for females than any of the other two powders after each period of exposure. Receptiveness of treated females to courting males was also decreased by exposure to any of the three powders. Similarly, E. aromatica powder caused greater decreases in female receptiveness to males than any of the other two powders after each period of exposure. Exposure of either adult male or female C. maculatus to the powders for sub-lethal times of three, six and nine hours significantly reduced the fecundity of the beetles. E. aromatica powder caused the most reduction of eggs laid and also significantly reduced fertility of the eggs.

Evaluation of the dust and methanol extracts of Garcinia kolae for the control of Callosobruchus maculatus (F.) and Sitophilus zeamais (Mots)

Insecticidal effects of different doses of the dust and methanol extracts of Garcinia kolae on Callosobruchus maculatus and Sitophilus zeamais were tested. The dust had no significant effect on the two insects, none of them died even at 3 d after treatment. The methanol extracts, however, had rapid lethal effects on both C. maculatus and S. zeamais. The mortality of C. maculatus by the lowest concentration of methanol extracts ranged from 95%-100% whereas in S. zeamais, the mortality ranged from 87.5%-100% and 70%-100% in concentrations of 1 g extract＋3 ml methanol and 1 g extract＋5 ml methanol, respectively, from 24 to 48 h. The least concentration of 1 g extract＋l 5 ml methanol had no significant lethal effect on Sitophilus zeamais.

Chemical Composition and Bioactivity of Lippia adoensis Hochst ex.Walp(Verneneaceae) Leaf Essential Oil Against Callosobruchus maculatus Fabricius(Coleoptera: Chrysomelidae)

Essential oil （EO） of Nigeria-grown Lippia adoensis leaf was analyzed using gas chromatography mass spectrometry （GCMS） and its fumigant and repellent properties against Callosobruchus maculatus were evaluated. Sixteen compounds predominated by monoterpenes were identified. The major compounds were Eucalyptol （28.36%）, α-Terpineol （25.99%）, γ-Terpinene （15.24%）, α-Pinene （5.08%）, 1H-Cyclopropa[a]naphthalene （4.25%） and 1, 3, 6, 10-Dodeeatetraene （3.74%）. Percentage mortality due to fumigant toxicity was dose- and exposure period-dependent. One hour after treatment （HAT）, application of L. adoensis leaf EO at 107 μL· L^-1 air caused significantly （p〈0.05） higher mortality （50.00%） than 0.00% mortality observed at 0-53 μL· L^-1 air, but not significantly （p〉0.05） different from 22.50% observed in 80 μL· L^-1 air. At 3 HAT, application ofL. adoensis EO at 80 μL· L^-1 air caused significantly higher mortality （90.00 %） than mortality observed at 0 μL· L^-1 air. At 6 HAT, application of L. adoensis EO at 53-107 μL· L^-1 air caused significantly higher mortality （100.00 %） than that was observed in the control. The same trend was observed at 12 HAT where 100 % mortality observed in 27-107 μL· L^-1 air was significantly greater than 13.33 % observed in the control. At 3 HAT, percentage repellence was significantly （p〈0.05） affected by doses. Application of EO at 10-30 μL· cm^2 caused class V repellence （86.67%-100%） compared with the control which caused class I repellence （0-20%）.

Combination of Piper guineense Essential Oil with Cowpea Varietal Resistance in Control of Cowpea Seed Beetle, Callosobruchus maculatus Fabricius (Coleoptera： Chrysomelidae： Bruchinae)

To reduce the risks associated with over-dependence on synthetic insecticides and ensure leguminous food security, an experiment was conducted to evaluate the potentials of integrating Piper guineense essential oil （PgEO） with cowpea varietal resistance in the control of cowpea seed beetle, Callosobruehus maculatus Fabricius. Four cowpea varieties （Sokoto, Drum, Oloyin and Gwallam） were studied. Data collected included oviposition, progeny emergence, Reproductive Efficiency （RE） and Percentage Seed Damage （PSD）. At first filial generation, numbers of eggs laid on Oloyin variety treated with 25 μL PgEO per 25 g cowpea seeds （2.15） were significantly （p〈0.05） lower than the values obtained in untreated cowpea （3.61） and hexane-treated seeds （3.07）. C. maculatus RE on Oloyin （33.73） was significantly （p〈0.05） lower than values obtained on other varieties （47.34-54.67） for seeds without PgEO; and were significantly greater than 0.00 observed on Oloyin seeds treated with 50 pL PgEO. PSD on Oloyin （6.63%） was significantly （p〈0.05） lower than the values obtained on Sokoto （10.04%） and Drum （9.79%） for seeds without PgEO, while there was no damage in Oloyin treated with 50 pL PgEO. Significantly （p〈0.05） lower F2 progeny emergence occurred on Oloyin （4.02） and Sokoto （4.71） compared with Drum （9.03） and Gwallam （6.07） from the untreated cowpea seeds. The results implied that application of PgEO to Oloyin gave better protection from infestation of C. maculatus than other varieties. Hence, combination of varietal resistance with PgEO for management ofbruchid could be an effective mean of improving cowpea food security.

Effects of Initial Infestation Levels of Callosobruchus maculatus (F.)(Coleoptera: Chrysomelidae) on Cowpea and Use of Nicotiana tabacum L.Aqueous Extract as Grain Protectant

This study determined the effects of initial infestation of cowpea seeds （Ife brown variety） with different insect densities （0, 2, 4 and 6 pairs per 50 g seeds） of Callosobruchus maculatus （F.） and evaluated the effects of aqueous leaf extract of Nicotiana tabacum L. on C. maculatus in the laboratory. It was observed that adult beetle population increased significantly （p〈0.05） with increase in insect density. The increase in population of beetles and corresponding weight loss of the seeds in different levels of infestation showed that the cowpea variety was susceptible to beetle infestation, emergence and survival of progeny. Significantly more adults emerged on higher infestation compared to lower and no infestation. In Nigeria, Nicotiana tabacum L. is a locally available plant, with known insecticidal properties. The plant leaf extract was easily extracted with water and confirmed its effectiveness as a protective agent for stored cowpea seeds. Experiment was conducted to assess the effects of aqueous extracts ofN. tabacum at 0, 0.1, 0.2 and 0.3 mL＂ 50 g-1 cowpea seeds on C. maculatus. Data was recorded and showed varying levels of effectiveness against C. maculatus. Result showed that seed appearance was dependent on levels of insect population, while N. tabacum aqueous extract exerted effects on survival of C. maculatus. Aqueous leaf extract of N. tabacum probably contained some insecticidal properties which might have significantly conferred beetle mortality and reduced beetle emergence leading to a decrease in seed weight loss.

The Role of Seed Coat and Its Pigmentation on the Acceptance of Bambara Groundnut (<i>Vigna subterranea </i>L. Verdc.) Cultivars by the Cowpea Beetle, <i>Callosobruchus maculatus</i>(F.)

Bambara groundnut, Vigna subterranea is an important legume crop that is adaptable to the dry regions of Africa. It is a major source of protein to people in many parts of Africa. One major constraint to increased production of the crop is the incidence of the storage pest Callosobruchus maculatus which causes significant weight loss to seeds in storage. The preference of the cowpea beetle C. maculatus for a particular seed coat colour was determined using four different colour types of bambara groundnut in an arena. The olfactory attractiveness of testa against cotyledon and cotyledon against whole grain was carried out in an olfactometer. Oviposition preference of C. maculatus on the different seed colours was determined. In the arena experiment significantly more of the beetles showed preference for cream and mottled seeds than red and black seeds. Significantly more beetles chose seeds with testa over decorticated seeds as well as whole grain over decorticated seeds. Colour significantly affected the seeds as oviposition sites. Significantly fewer eggs were laid on red and black seeds than cream seeds in both the choice and no choice tests (P < 0.0001). Thus for the purpose of reducing losses of seeds in storage it is advisable to cultivate red- and black-coloured seeds which showed lower acceptability to C. maculatus as oviposition site.

Evaluation of the Insecticidal Activity of Powders of Ageratum conyzoide L. Leaves and Roots of Securidaca longepedunculata Fresen on the Germination Rate of Cowpea Infected with Callosobruchus maculatus

Cowpea is a vegetable that contributes to food security in Guinea. Despite its importance, more than 30% of its production is lost between harvesting, storage and consumption. The main cowpea pest is Callosobruchus maculatus. The commonly used control strategy is essentially based on chemicals whose use is toxic, expensive and restrictive. In the search for alternatives to chemical control, this work was undertaken to evaluate the insecticidal potential of Ageratum conyzoid leaf powders and Securidaca longepedunculata roots. Powder toxicity and insecticidal efficacy tests were performed separately on groups of 20 Callosobruchus maculatus using 3 doses of Ageratum conyzoid leaf powders and Securidaca longepedunculata roots in jars each containing 100 g cowpea. The mortality of Callosobruchus maculatus and the impact of powders were noted respectively for 96 h and 4 months after infestation. The germination capacity of the treated seeds was assessed at the start of the study. Doses of 1 and 8 g of Ageratum conyzoides leaf powders and Securidaca longepedunculata roots were applied respectively to every 100 g of cowpea and led to 100% mortality of Callosobruchus maculatus. At these same doses, more than half of the treated seeds were attacked during the 4 months of storage. Germination tests have shown that powders of Ageratum conyzoides leaves and roots of Securidaca longepedunculata have no negative effect on the germination power of cowpea seeds. Therefore, they could be considered as excellent bio-insecticides that socio-professional strata (farmers and warehouse workers) can use in the fight against cowpea insects intended for storage.

丁酸梭菌对花鲈幼鱼生长性能、免疫消化及肠道菌群的影响

【目的】探究丁酸梭菌(Clostridium butyricum)对花鲈(Lateolabrax maculatus)幼鱼生长性能,消化、免疫和抗氧化能力及肠道菌群的影响,为丁酸梭菌在花鲈鱼养殖中的应用提供理论依据。【方法】以花鲈幼鱼为试验材料设饲料中丁酸梭菌添加量为0(D0,对照)、0.25%(D1)、0.50%(D2)、1.00%(D3)、2.00%(D4)和4.00%(D5)6组,投喂花鲈幼鱼56 d,测定其生长性能、肠道消化酶活性、血清生化和免疫指标及肠道形态指标,分析肠道菌群组成。【结果】丁酸梭菌可显著降低饲料系数(P<0.05,下同),显著提高花鲈幼鱼的终末平均体质量,D3、D4和D5组的增重率及特定生长率均显著高于D0组。与D0组相比,D4组肠道糜蛋白酶和脂肪酶活性均显著提高,血清总胆固醇、甘油三酯含量和谷草转氨酶、谷丙转氨酶活性均显著降低。D4组溶菌酶、碱性磷酸酶和总一氧化氮合酶活性均显著高于D0组,D3组酚氧化酶活性显著高于D0组;与D0组相比,D3和D5组过氧化氢酶活性及总抗氧化能力均显著提高,D4组超氧化物歧化酶活性显著提高,丙二醛含量显著降低。D2、D3和D5组花鲈幼鱼肠道肌层厚及绒毛高度均显著高于D0组。D3组花鲈幼鱼肠道菌群OTU数量和Chao1指数均显著高于D0组,各试验组花鲈幼鱼肠道菌群Simpson指数和Shannon指数均显著高于D0组;在门分类水平上,丁酸梭菌降低了变形菌门和厚壁菌门相对丰度,提高了放线菌门、浮霉菌门、酸杆菌门、绿弯菌门、拟杆菌门和芽单胞菌门相对丰度;在属分类水平上,丁酸梭菌降低了劳尔氏菌属、肠弧菌属和弧菌属有害菌相对丰度,提高了节杆菌属和KD4-96_unclassified有益菌相对丰度。【结论】饲料中添加丁酸梭菌能显著提高花鲈幼鱼生长性能,提高消化、免疫和抗氧化能力,调节肠道菌群结构组成及其相对丰度,提高肠道菌群多样性,以2.00%添加量效果最好。

我国花鲈综合养殖模式研究进展

花鲈是我国重要的海产经济鱼类,其养殖生产方式较为多样,但传统养殖方式易造成水体富营养化、水底带环境恶化及底栖生物群落结构改变等生态环境问题。综合养殖作为一种可持续的养殖模式,是应对上述问题的有效方法。本文对花鲈养殖产业发展现状、花鲈池塘综合养殖模式和陆基循环系统综合养殖模式进行了总结与综述,探究了技术手段与路径,并对花鲈综合养殖模式的产业化应用及前景进行展望。相关结果和结论为花鲈综合养殖生产与管理、花鲈综合养殖技术模式的开发与应用提供了有用的技术资料。

不同综合养殖条件对花鲈和刺参生长性能及生化指标的影响

本文探究池塘综合养殖花鲈和刺参在不同密度和水深条件下生长性能、存活率(SR)和非特异性免疫酶(超氧化物歧化酶SOD、溶菌酶LSZ)活性的差异。采用池塘围隔对比法开展科学实验,结果表明:综合养殖密度对花鲈和刺参生长性能的影响较为明显,但对其SR、SOD和LSZ活性的影响未见显著(P>0.05)。Ca密度即花鲈2.0 ind./m2、刺参5.0 ind./m2为其适宜的池塘综合养殖密度;在实验水深范围内,综合养殖花鲈、刺参在不同深度生长参数、SR和非特异性免疫酶(SOD、LSZ)活性差异均不明显(P>0.05),但花鲈生长性能已呈现随水深增大而逐渐增强的趋势,刺参则与之相反。2.0 m为花鲈和刺参池塘综合养殖适合的水深。本研究为海水池塘多营养级综合养殖模式的开发与应用积累了有用的技术资料。

花鲈肠上皮细胞原代培养及鉴定方法的探讨研究

为探究建立稳定可靠的花鲈肠上皮细胞原代培养方法,通过组织块法和酶消化法培养花鲈肠上皮细胞,确定酶消化法的最佳消化液及消化时间,所得细胞悬液于L-15培养液中进行培养。利用形态学观察、透射电镜观察和碱性磷酸酶染色方法对细胞进行鉴定。结果显示:组织块法细胞迁出情况不稳定,且迁出时间较长;酶消化法的最佳消化液为胶原酶Ⅰ、Ⅳ联合消化液,最佳消化时间为45 min;胶原酶Ⅰ、Ⅳ联合消化法获得的细胞连接紧密、排列整齐、呈上皮细胞典型的“铺路石”状,细胞相对独立、界限清晰。透射电镜观察和碱性磷酸酶染色进一步证实所培养的细胞为肠上皮细胞。总之,经胶原酶Ⅰ、Ⅳ联合消化液消化45 min、培养48 h可得到初始条件一致、生长旺盛的花鲈原代肠上皮细胞。

不同胆汁酸对花鲈生长、血清生化及肝脏脂代谢的影响

为研究不同胆汁酸对花鲈生长性能、血清生化及脂肪代谢的影响,选取240尾体格健壮、规格一致的花鲈((16.00±0.50)g),随机分到12个养殖桶中,分别饲喂基础饲料(不添加胆汁酸)、添加载体胆汁酸的饲料、添加脂壮素NE的饲料和添加液体胆能L的饲料,投喂8周后,采集样品并分析。结果表明:1)与基础饲料组相比,脂壮素NE组显著提高了花鲈的增重率、摄食量和血清溶菌酶活性(P<0.05);液体胆能L组显著降低增重率和摄食量(P<0.05),对血清非特异性免疫无显著影响(P>0.05);而载体胆汁酸组对花鲈增重率和血清非特异性免疫均无显著影响(P>0.05)。2)3种不同剂型胆汁酸的添加均可显著降低血清谷草转氨酶、肝脏乙酰辅酶A羧化酶的活性(P<0.05),且脂壮素NE组的肝脏脂蛋白脂酶活性增加显著(P<0.05)。综上所述,饲料中添加脂壮素NE后会显著提高花鲈的增重率和血清中溶菌酶、肝脏中脂蛋白脂酶的活性。

不同生长阶段中国花鲈肠道和环境微生物群落分析

为探究中国花鲈(Lateolabrax maculatus)不同生长阶段肠道和养殖环境微生物组成,选择3月龄(小规格组,体质量为79.89 g±14.97 g)、6月龄(中规格组,体质量为212.67 g±30.32 g)和9月龄(大规格组,体质量为427.56 g±69.56 g)3个不同生长阶段的中国花鲈,采集其肠道微生物和环境微生物(养殖水和池塘底泥)进行16S rDNA基因测序数据分析。结果表明:不同月龄的中国花鲈肠道微生物与环境微生物群落结构有较大差异,而不同生长阶段的环境微生物群落结构则无显著性差异(P>0.05);环境微生物中双色藻属(Cyanobium_PCC-6307)作为差异物种,表现出与硝酸盐氮呈负相关;肠道微生物分析显示,门水平上,3月龄和6月龄中国花鲈肠道中厚壁菌门(Firmicutes)丰度低于9月龄中国花鲈,属水平上,3月龄和6月龄中国花鲈肠道中富集的可促进糖利用的鲸杆菌属(Cetobacterium)丰度高于9月龄中国花鲈,罗姆布茨菌属(Romboutsia)肠道微生物差异贡献度最高。研究表明,不同养殖阶段的环境微生物群落结构无显著性差异,不同月龄中国花鲈间的肠道微生物群落结构有显著性差异,中国花鲈肠道微生物群落结构受养殖环境的影响。

花鲈和大口黑鲈肌肉营养品质评价

通过探究不同质量规格花鲈(Lateolabrax maculatus)和大口黑鲈(Micropterus salmoides)的营养物质变化,分析其生长过程中营养物质积累规律及营养品质。结果表明,在花鲈和大口黑鲈肌肉中均检测出16种氨基酸,包括7种必需氨基酸(EAA)、2种半必需氨基酸(SEAA)和7种非必需氨基酸(NEAA)。花鲈和大口黑鲈肌肉中蛋白质含量在18.20%~21.80%,脂肪含量在1.24%~4.25%,水分含量在72.10%~78.30%,灰分含量在1.14%~1.31%,总氨基酸含量在17.37%~20.72%,必需氨基酸含量在7.01%~8.21%,鲈鱼营养物质的种类齐全且搭配均衡。花鲈和大口黑鲈在营养组成上有一定差异,不同质量规格的鲈鱼营养成分不尽相同。大型花鲈的各种氨基酸含量均最大,且与其他花鲈样品具有显著差异(P<0.05);大型大口黑鲈的各种氨基酸含量均最大,且大部分氨基酸含量与其他大口黑鲈样品有显著差异(P<0.05),说明大型鲈鱼在生长过程中积累了更多的氨基酸。从氨基酸的评分均衡性上分析,中型鲈鱼最适宜食用。