Screening of Saprolegniasis Preventive Drugs for Golden Trout (Oncorhynchus mykiss) Fertilized Eggs During Hatching

In order to screen the effective preventive drugs for saprolegniasis occurred during hatching of the fertilized eggs of golden trout, effects of two kinds of self-made Chinese herbal compounds（AB） and two kinds of chemical bactericides（peroxyacetic acid andhydrogen peroxide, CD） with three disinfection concentrations were compared in this study. The fertilized eggs of golden trout were randomly divided into 13 groups, each group with two parallels of 1 000 eggs. Drugs at high,medium and low concentration were respectively used to immerse the fertilized eggs35 min for disinfection once a day. The numbers of live and dead eggs were recorded each day before disinfection and the numbers of survival eyed eggs were counted in each experimental group after finishing the whole test. The results indicated that all of four kinds of drugs used here had a certain effect on prevention and control of saprolegniasis during hatching of fertilized eggs of golden trout, and also showed a correlation between the concentrations and effects. After the selection of several drugs, we found that group B-medium, C-medium and D-high exhibited the most remarkable effects on control of saprolegniasis. However, careful consideration should be given to chemical drugs residues and their potential hazard to the eyed eggs. Therefore, Chinese herbal compound B was suggested to be used for prevention and control of saprolegniasis to achieve the healthy aquaculture. And the concentration and operation time of Chinese herbal compound B should be strictly controlled when used in disinfection of fertilized eggs.

Virtual screening,molecular docking and identification of umami peptides derived from Oncorhynchus mykiss

Oncorhynchus mykiss is delicious and contains abundant flavor substances.However,few studies focused on umami peptides of O.mykiss.In the current work,umami peptides derived from O.mykiss were identified using virtual screening,molecular docking,and electronic tongue analysis.First,the O.mykiss protein was hydrolyzed using the PeptideCutter online enzymolysis program.Subsequently,water-soluble and toxicity screening were performed by Innovagen and ToxinPred software,respectively.The potential peptides were docked with umami receptor T1R1/T1R3.Furthermore,taste properties of potential peptides were validated by electronic tongue.Docking results suggested that the three tetrapeptide EANK,EEAK,and EMQK could enter the binding pocket in the T1R1 cavity,wherein Arg151,Asp147,Gln52,and Arg277 may play key roles in the production of umami taste.Electronic tongue results showed that the umami value of EANK,EEAK,and EMQK were stronger than monosodium glutamate.This work provides a new insight for the screening of umami peptides in O.mykiss.

GFAP expression in the optic nerve and increased Н2S generation in the integration centers of the rainbow trout（Oncorhynchus mykiss） brain after unilateral eye injury

Hydrogen sulfide(H2S)is considered as a protective factor against cardiovascular disorders.However,there are few reports on the effects of H2S in the central nervous system during stress or injury.Previous studies on goldfish have shown that astrocytic response occurs in the damaged and contralateral optic nerves.Glial fibrillary acidic protein(GFAP)concentration in the optic nerves of rainbow trout has not been measured previously.This study further characterized the astrocytic response in the optic nerve and the brain of a rainbow trout(Oncorhynchus mykiss)after unilateral eye injury and estimated the amount of H2S-producing enzyme cystathionineβ-synthase(CBS)in the brain of the rainbow trout.Within 1 week after unilateral eye injury,a protein band corresponding to a molecular weight of 50 kDa was identified in the ipsi-and contralateral optic nerves of the rainbow trout.The concentration of GFAP in the injured optic nerve increased compared to the protein concentration on the contralateral side.The results of a quantitative analysis of GFAP+cell distribution in the contralateral optic nerve showed the largest number of GFAP+cells and fibers in the optic nerve head.In the damaged optic nerve,patterns of GFAP+cell migration and large GFAP+bipolar activated astrocytes were detected at 1 week after unilateral eye injury.The study of H2S-producing system after unilateral eye injury in the rainbow trout was conducted using enzyme-linked immunosorbent assay,western blot analysis,and immunohistochemistry of polyclonal antibodies again st CBS in the integrative centers of the brain:telencephalon,optic tectum,and cerebellum.Enzyme-linked immunosorbent assay results showed a 1.7-fold increase in CBS expression in the rainbow trout brain at 1 week after unilateral eye injury compared with that in intact animals.In the ventricular and subventricular regions of the rainbow trout telencephalon,CBS+radial glia and neuroepithelial cells were identified.After unilateral eye injury,the number of CBS+neuroepithelial cells in the pallial and subpallial periventricular regions of the telencephalon increased.In the optic tectum,unilateral eye injury led to an increase in CBS expression in radial glial cells;simultaneously,the number of CBS+neuroepithelial cells decreased in intact animals.In the cerebellum of the rainbow trout,neuroglial interrelationships were revealed,where H2S was released,apparently,from astrocyte-like cells.The organization of H2S-producing cell complexes suggests that,the amount of glutamate produced in the rainbow trout cerebellum and its reuptake was controlled by astrocyte-like cells,reducing its excitotoxicity.In the dorsal matrix zone and granular eminences of the rainbow trout cerebellum,CBS was expressed in neuroepithelial cells.After unilateral eye injury,the level of CBS activity increased in all parts of the cerebellum.An increase in the number of H2S-producing cells was a response to oxidative stress after unilateral eye injury,and the overproduction of H2S in the cerebellum occurred to neutralize reactive oxygen species,providing the cells of the rainbow trout cerebellum with a protective effect.A structural reorganization in the dorsal matrix zone,associated with the appearance of an additional CBS+apical zone,and a decrease in the enzyme activity in the dorsal matrix zone,was revealed in the zones of constitutive neurogenesis.All experiments were approved by the Commission on Biomedical Ethics,A.V.Zhirmunsky National Scientific Center of Marine Biology(NSCMB),Far Eastern Branch,Russian Academy of Science(FEB RAS)(approval No.1)on July 31,2019.

Neurolin expression in the optic nerve and immunoreactivity of Pax6-positive niches in the brain of rainbow trout(Oncorhynchus mykiss) after unilateral eye injury

In contrast to astrocytes in mammals, fish astrocytes promote axon regeneration after brain injury and actively participate in the regeneration process. Neurolin, a regeneration-associated, Zn8-1abeled protein, is involved in the repair of damaged optic nerve in goldfish. At 1 week after unilateral eye injury, the ex- pression of neurolin in the optic nerve and chiasm, and the expression of Pax6 that influences nervous system development in various brain regions in the rainbow trout （Oncorhynchus mykiss） were detected. Immunohistochemical staining revealed that the number of Zn8~ cells in the optic nerve head and intraor- bital segment was obviously increased, and the increase in Zn8~ cells was also observed in the proximal and distal parts of injured optic nerve. This suggests that Zn8＊ astrocytes participate in optic nerve regeneration. ELISA results revealed that Pax6 protein increased obviously at 1 week post-injury. Immunohistochemi- cal staining revealed the appearance of Pax6＋ neurogenic niches and a larger number of neural precursor cells, which are mainly from Pax6＋ radial glia cells, in the nuclei of the diencephalon and optic tectum of rainbow trout （Oncorhynchus mykiss）. Taken together, unilateral eye injury can cause optic nerve reaction, and the formation of neurogenic niches is likely a compensation phenomenon during the repair process of optic nerve injury in rainbow trout （Oncorhynchus mykiss）.

Compensatory growth response of rainbow trout Oncorhynchus mykiss Walbaum following short starvation periods

This sixty-day study was performed to determine the effects of short-term starvation and refeeding cycles on growth, feeding performances and body composition of rainbow trout （Oncorhynchus mykiss）. Three hundred trout fingerlings with an average initial weight of 17.54-0.06 g were randomly distributed in 15 circular fiberglass tanks. The fish were exposed to 5 different feeding regimes; control： continuously fed twice daily to apparent satiation; T1： starved for 1 day and re-fed for 2 days; T2： starved for 1 day and re-fed for 4 days; T3： starved for 3 days and re-fed for 12 days; T4： starved for 4 days and re-fed for 16 days. At the end of the experiment, growth performance, feed utilization, whole body ash and moisture contents were not significantly （P〉0.05） different among the treatments. However, whole body protein content in T3 was significantly higher than other treatments （P〈0.05）. A significant difference in whole body fat content was observed between T3 and the control group at the end of the experiment （P〈0.05）. In conclusion this experiment suggests that feeding schedules involving starvation （1-4 days） and re-feeding cycles are a promising feed management tool for rainbow trout culture.

Effects of Ferrous Fumarate on Growth Performance,Blood Biochemical Parameters and Trace Elements of Oncorhynchus mykiss

[ Objective] The study aimed to discuss the effects of ferrous fumarate on growth performance, blood biochemical parameters and content of trace element of Oncorhynchus mykiss. [ Method ] Juvenile rainbow trout with an initial weight of （89.2 ±0.2） g were fed with the basal fodder supplemented with different levels of ferrous fumarate （0, 20, 40, 80,160 and 480 mg/kg iron） for 60 d, and the six groups were named DO, D20, D40, D80, D160 and D480, wherein DO was as the control group, actually containing 62.60, 79.50, 99.60, 139.30, 215.20 and 538.40 mg/kg iron respectively. [ Result] The growth performance of juvenile rainbow trout was not affected by different dietary iron levels obviously （ P 〉 0.05）. With the increase of dietary iron level, hemoglobin （Hb） content and number of red blood cells（RBC） rose firstly and then leveled off. No significance was found in hematocrit （Hct） among the six groups （P 〉0.05）. Iron content in the whole body, vertebrae and muscle increased significantly with the improvement of dietary iron level（ P 〈0.05）, and iron concentration in the liver increased firstly and then leveled off in groups from D40 to D480. No significant difference in zinc content of the whole body was found among the six groups （ P〉0.05）, while zinc content in the vertebrae and muscle in control group was significantly higher than that of other groups （ P〈0.05）, and zinc concentration in the liver in groups DO and 1320 was significantly higher than that of other groups （ P 〈0.05）. Copper content in the whole body increased significantly with the increase of dietary iron level （P 〈 0.05 ）, while no significant difference was observed in the vertebrae （ P 〉0.05）, and copper concentration in the muscle in control group was significantly lower than that of other groups （ P 〈0.05）. Serum lysozyme （LZM） activity of group DO was significantly lower than that of other groups （ P 〈 0.05） except for group D480 （ P 〉 0.05）. Catalase （CAT） activity of serum enhanced significantly （ P 〈 0.05） from DO to EH0 and then decreased obviously （P 〈0.05）. [ Conclusion] Based on hemoglobin and iron content in the liver, the broken-line model analysis showed that the dietary iron level provided by ferrous fumarate for juvenile rainbow trout was estimated to be 99.8 and 100.4 mg/kg respectively in the experiment.

Combined Effects of Dietary Bacillus subtilis and Trans-cinnamic Acid on Growth Performance,Whole Body Compositions,Digestive Enzymes and Intestinal bacteria in Rainbow Trout(Oncorhynchus mykiss)

In this study,the combined effects of dietary Bacillus subtilis(BS,107 g/cfu)and different levels(0.025%,0.050%,0.075%and 0.150%)of trans-cinnamic acid(CA)on fish growth performance,whole body compositions,digestive enzymes,intestinal bacteria and internal organ index of rainbow trout(Oncorhynchus mykiss)were investigated.Six different experimental groups including control group(C),C+BS,0.025%CA+BS,0.050%CA+BS,0.075CA+BS,0.150%CA+BS)were established.According to the results obtained,growth performance,whole body compositions and digestive pH were not statistically significant among groups.Further,no significant differences were found between experimental groups in terms of the intestinal enzymes(trypsin,alkaline phosphatase and lipase)and gastric pepsin.Significantly higher levels of intestinal amylase were found in the control+BS,0.025%CA+BS,0.050%CA+BS,and 0.075%CA+BS compared to the control and 0.150%CA+BS groups.Moreover,coliform and Enterobacteriaceae counts were highest in the control+B.subtilis and lowest in the 0.150%CA+B.subtilis groups.

Evaluation of Growth Performance of a Genetically Characterized F1 Rainbow Trout,Oncorhynchus mykiss in a Recirculating Aquaculture System

The growth performance of a selected F1 rainbow trout genetically characterized as polymorphic with locus Omy207UoG (NA = 13, PIC = 0.891, HE = 0.9003) was evaluated in a recirculating aquaculture system (RAS). A set of 157 rainbow trout of 37.8 g of mean body weight and 14.6 cm mean total length per tank, were introduced in each of six fish tank of 5 m3 connected to a recirculating aquaculture system (RAS). The trout was rearing during 317 days. Growth performance indicators and water quality were evaluated during the experiment. The genetically selected F1 rainbow trout showed a tendency towards homogeneity in growth performance along the culture period, reaching a mean total weight of 552.2 g. The length-weight relationship indicated an isometric growth (>3.0). This study presents the basis to establish a long-term marker-assisted selection program for rainbow trout culture in a subtropical region.

Influence of Carvacrol on the Growth Performance,Hematological,Non-Specific Immune and Serum Biochemistry Parameters in Rainbow Trout(Oncorhynchus mykiss)

The present study investigated the effects of phytoadditive carvacrol on growth performance, feed utilization, hematological, non-specific immune and serum biochemical parameters in rainbow trout (Oncorhynchus mykiss). In trial, 240 rainbow trout which had average weight of 10.79 ± 0.57 was used. Fish were divided into four groups before being fed for 60 days with 0, 1 (C1), 3 (C3) or 5 (C5) g/kg of carvacrol. There were no particular differences in the growth performance, feed utilization, whole body composition, hematological parameters between the experimental group and the control group. However, as compared to control group, a significant increase of serum lysozyme activity was seen in groups receiving feed containing C3 and C5 groups after 30 days. The myeloperoxidase activity in groups (C1 and C3) was significantly higher on the 30th day of sampling. Myeloperoxidase activity of C5 treated group was significantly higher on the 60th day in comparison with the control group. Serum glucose levels significantly decreased on 60th day for C1, C3 and C5 treated groups. The serum total protein, globulin and triglyceride levels of C3 treated groups was significantly higher on the 60th day in comparison with the control and other carvacrol treated groups. The level of serum cholesterol in C5 treated groups was significantly lower on the 30th day in comparison with the control and other carvacrol treated groups. The results of the present study indicated that dietary supplementation of 3 g/kg of carvacrol in commercial diets could improve some non-specific and biochemical status in rainbow trout.

Mucosal immune responses to Ichthyophthirius multifiliis in the ocular mucosa of rainbow trout(Oncorhynchus mykiss,Walbaum),an ancient teleost fish

The eye,as a specialized visual organ,is directly exposed to the external environment,and,therefore,it faces constant chal-lenges from external pathogenic organisms and toxins.In the ocular mucosa(OM)of mammals,mucosal-associated lymphoid tissues(MALTs)constitute the primary line of defense.However,the immune defense role of the OM remains unknown in aquatic vertebrates.To gain insights into the immune processes within the OM of teleost fish,we developed an infection model of rainbow trout(Oncorhynchus mykiss)OM using a parasite,Ichthyophthirius multifiliis(Ich).Immunofluorescence,qPCR,and H&E staining revealed that Ich successfully infiltrates the OM of rainbow trout,leading to pathological struc-tural changes,as evidenced by A&B staining.Importantly,the qPCR results indicate an up-regulation of immune-related genes following Ich infection in the OM.Moreover,transcriptome analyses were conducted to detect immune responses and impairments in eye function within the OM of rainbow trout with Ich infection.The results of the transcriptome analysis that Ich infection can cause an extensive immune response in the OM,ultimately affecting ocular function.To the best of our knowledge,our findings represent for the first time that the teleost OM could act as an invasion site for parasites and trigger a strong mucosal immune response to parasitic infection.

Quality of Semi-Prepared Products from Rainbow Trout Waste(Onchorynchus mykiss)by Using Different Technological Strategics

The consumption of freshwater fish and fish products has gradually grown worldwide over the last decades, generating a proportional waste increase. The objective of the present study was to assess the chemical and bacteriological quality of restructured fish product, meatball-type, prepared with rainbow trout (Onchorynchus mykiss) waste added of 1% transglutaminase (MTG), 4% textured soy protein (TSP) and replacing part of the sodium chloride with potassium chloride (75%/25%) as described below: T1—starch addition (control);T2—MTG addition (1%);T3—soy protein addition (4%);T4—soy protein addition (4%) and MTG addition (1%);T5—soy protein addition (4%), MTG addition (1%) and partial replacement of salt (75% NaCl/25% KCl). Total aerobic mesophilic bacteria (TAMB), 2-thiobarbituric acid reactive substances (TBARS), pH determination and quantification of biogenic amines were performed on the day after manufacturing (P0) and after 60 days of storage (P1) at -25℃?± 2℃. The results showed that there was no significant difference (p < 0.05) of microbiological quality, TBARS and pH after storage. T4 presented the lowest total biogenic amine content (256.84 mg/kg) whereas T3 and T5 had the highest value (791.36 and 707.19 mg/kg, respectively) in this parameter. Putrescine was the biogenic amine that presented the highest concentration (504.00 mg/kg) in T3 and cadaverine that presented the smallest concentration (0.36 mg/kg) in T4. The use of technological strategies for developing new products with non-commercial fillets kept the most standards, having changes only in some biogenic amines.

养殖密度对三倍体虹鳟苗种生长性能的影响

该研究旨在探讨不同养殖密度对三倍体虹鳟(Oncorhynchus mykiss)苗种生长性能的影响。选取体重0.17 g,体长2.93 cm的同批次开口苗种16800尾,试验设置200、400、600、800、1000、1200尾6个养殖密度组,分别为M1组、M2组、M3组、M4组、M5组、M6组,每组3个重复。试验周期2个月,其间记录幼苗体长(cm)、体重(g)及成活率。结果显示,M3组的肥满系数及成活率数值最高,与其他组存在显著性差异(P<0.05);其试验末体重、体长、增重率、特定生长率与M2组不存在显著性差异(P>0.05);生长性能表现最佳的为M1组,但M1组的成活率仅为93.2%,与M3组成活率98.1%存在显著性差异(P<0.05)。研究结果表明,在水温11℃~13℃的养殖条件下,三倍体虹鳟稚鱼的最佳养殖密度为M3组(6667尾/m~3),其生长性能及存活率表现较佳。

静水压法诱导虹鳟三倍体试验

以虹鳟(Oncorhynchus mykiss)二倍体雌鱼为母本,二倍体伪雄鱼为父本,采用静水压法,研究诱导虹鳟三倍体的产生,初步探索静水压法诱导虹鳟三倍体的适宜条件。结果显示,虹鳟三倍体诱导率受处理起始时间、处理压力和持续时间的影响。静水压诱导虹鳟三倍体的最佳条件为处理起始时间30 min~40 min,静水压压力65 MPa~70 MPa,持续时间4 min~6 min。

盐度驯化对虹鳟和金鳟Na^(+)/K^(+)-ATP酶活力、皮质醇含量及其组织结构的影响

为探究不同盐度驯化对虹鳟(Oncorhynchus mykiss)和金鳟(Oncorhynchus mykiss)的鳃的影响,以盐度0为对照,研究了15‰和30‰两种盐度驯化虹鳟和金鳟后,鱼体鳃、血清中Na^(+)/K^(+)-ATP酶活力、血清中皮质醇含量和鳃、肾脏的组织学变化。试验结果表明,与对照组相比,低盐度下随驯化盐度提高,虹鳟、金鳟鳃部Na^(+)/K^(+)-ATP酶活力均呈增加趋势,但高盐度驯化时二者鳃部Na^(+)/K^(+)-ATP酶活力受抑制,血清中Na^(+)/K^(+)-ATP酶活力较低,且活力随盐度变化不大。血清皮质醇浓度随着驯化盐度增加而升高,盐度30‰条件下虹鳟和金鳟血清中皮质醇的含量达到最高值。虹鳟和金鳟的组织切片结果显示,驯化盐度过高时对二者肾脏和鳃组织均造成破坏,肾脏组织表现为肾小囊及肾小球遭到破坏并完全消失,鳃组织出现明显的氯细胞数量激增和鳃丝上皮脱落且鳃丝变细变长。

高温胁迫对三倍体虹鳟血清生化指标的影响

为研究不同温度(18、21、24、27℃)对三倍体虹鳟(Oncorhynchus mykiss)血清生化指标的影响,选取300尾三倍体虹鳟,随机分为4组,每组3个重复,每个重复25尾,饲养72 h。结果表明,三倍体虹鳟在23℃出现应激反应,呼吸频率升高;血清中谷丙转氨酶(ALT)和谷草转氨酶(AST)活性24、27℃组在72 h显著高于18、21、24℃组(P<0.05);碱性磷酸酶(AKP)活性随着温度提升和时间持续而降低,18℃组在48、72 h显著高于21、24、27℃组(P<0.05);总胆红素(T-BIL)含量随着温度增高而增加,在24、48、72 h各组之间呈现出显著性差异(P<0.05);总蛋白(TP)、球蛋白(GLO)含量随着温度的增高先上升后降低;白蛋白(ALB)含量24℃组呈现上升趋势,27℃组呈现出下降趋势,组内不同时间呈现显著差异(P<0.05)。研究表明,三倍体虹鳟在23℃水温刺激下表现出应激性反应,温度高于24℃的阶段性短期热应激对三倍体虹鳟肝功能具有明显损伤,影响其生长生存。

甘肃地区几种鲑鳟鱼肌肉营养成分比较与评价

为了解甘肃地区养殖鲑鳟鱼的营养价值与鲜美程度,采用常规营养测试方法测定虹鳟(Oncorhynchus mykiss)、金鳟(golden Oncorhynchus mykiss)、亚东鲑(Salmo trutta fario)及七彩鲑(Salvelinus fontinalis)四种商品鱼(体质量835.72~989.12 g)的肌肉营养成分。结果显示:鱼肌肉(鲜样)中水分的质量分数为70.80%~75.00%、粗蛋白18.40%~19.20%、粗脂肪4.00%~10.10%和粗灰分1.20%,除粗灰分含量外各组间差异显著,金鳟是典型高蛋白高脂肪品种。共检测出18种氨基酸,其中人体必需的8种氨基酸总量为7.69%~8.43%(干样,下同);4种鲑鳟鱼肌肉中必需氨基酸组成均与FAO/WHO要求一致,必需氨基酸指数为84.40~86.56;限制性氨基酸一致为色氨酸,4种鲜味氨基酸总质量分数为38.52%~39.25%,各组间差异显著,从各种氨基酸分析得出亚东鲑是相对组成最理想的品种。肌肉中脂肪酸含量丰富(21~23种),多不饱和脂肪酸含量达1.80%~4.83%,其中DHA+EPA含量为0.39%~0.90%,各组间差异显著,但虹鳟保健价值更有优势。9种常见的矿物元素被检测出,各组间差异显著,其中七彩鲑矿物元素相对较高,生理功效突出。研究表明4种养殖鲑鳟鱼营养价值均较高。

三倍体虹鳟发眼卵恒温盐碱冷流水人工孵化与培育技术

在甘肃省白银市平川区的恒温盐碱冷流水孵化车间开展了三倍体虹鳟(Oncorhynchus mykiss)发眼卵人工孵化及鱼苗培育试验,通过水质调控、疫病防控、营养强化、科学投饵等关键技术方法,探索出三倍体虹鳟发眼卵恒温盐碱冷流水人工孵化与鱼苗培育模式,试验取得较好的经济效益,三倍体虹鳟发眼卵孵化率达到了92%,鱼苗成活率达到80%以上。

喀喇沁旗截潜流工程取水流水池养殖虹鳟技术

截潜流工程取水养殖虹鳟(Oncorhynchus mykiss)技术是利用潜流水具有水温低、温差变化小的特点开展虹鳟养殖。潜流水出水口平均温度7℃~12℃,北方地区冬天也不结冰。在赤峰市喀喇沁旗十家村山坡河道上建设截潜流工程和虹鳟养殖池,利用截潜流工程自流引水养殖虹鳟“水科1号”,取得较好的养殖效果。相关养殖技术可供有关专业人员参考。

红枣提取物对虹鳟血清指标和头肾免疫相关基因表达的影响

为了探讨添加红枣提取物对促进虹鳟(Oncorhynchus mykiss)机体健康的可能性,选取体长为7.2~8.4 cm的健康虹鳟,随机分成4个试验组,分别投喂红枣提取物添加量为0%(对照组)、0.25%、0.50%和1.00%的等氮等脂饲料,饲养56 d,养殖结束后测定12项血清生化指标和头肾的6个免疫相关基因mRNA表达量。结果显示:与对照组相比较,血清中肌酐(CREA)和尿素氮(BUN)含量三个红枣提取物组均出现极显著下降;谷丙转氨酶(GPT)活性在0.50%和1.00%组极显著下降,谷草转氨酶(GOT)活性也在0.50%和1.00%组出现了一定程度下降,但差异不显著;酸性磷酸酶(ACP)和碱性磷酸酶(AKP)活性无显著变化;总蛋白(TP)和白介素6(IL-6)含量在0.25%组出现显著增加;溶菌酶(LZM)活性三个红枣提取物组均显著升高;超氧化物歧化酶(SOD)活性在0.50%组极显著增加;补体4(C4)和肿瘤坏死因子(TNF-α)含量在0.25%和0.50%组均极显著增加。在头肾中,与对照组相比,SOD、白介素1β(IL-1β)和补体3(C3)基因表达量在0.50%和1.00%组均为显著或极显著上调;Factor H基因表达量在0.50%组显著上调;过氧化氢酶(CAT)和LZM基因表达量在0.50%和1.00%组仅出现差异不显著上调。上述结果表明,在虹鳟饲料中添加一定量的红枣提取物,可以起到促进肾功能,保护肝脏和提高其非特异性免疫功能的作用。

虹鳟杀鲑气单胞菌耐药性研究与盐酸多西环素给药方案制定

为科学制定虹鳟(Oncorhynchus mykiss)杀鲑气单胞菌(Aeromonas salmonicida)病的给药方案,对3株分离自虹鳟的杀鲑气单胞菌采用纸片扩散法(K-B法)进行24种抗生素耐药性测定,并对其中4种敏感且批准使用的抗生素进行体外药效学实验,研究20、30、40和60 mg/kg盐酸多西环素在染病虹鳟体内的药代动力学特征。结果显示:3株杀鲑气单胞菌对复方新诺明、磺胺异恶唑、青霉素、阿莫西林、头孢唑林耐药,对盐酸多西环素最敏感,其最小抑菌浓度(MIC)为0.5μg/mL,最小杀菌浓度(MBC)在2~4μg/mL之间,防耐药突变浓度(MPC)为1μg/mL;恩诺沙星的MIC在0.25~1μg/mL之间,MBC为4μg/mL,MPC为1.5μg/mL;氟苯尼考的MIC为1μg/mL,MBC为8μg/mL,MPC为2μg/mL;硫酸新霉素MIC为4μg/mL,MBC为8μg/mL,MPC为12μg/mL。40 mg/kg剂量单次给药,盐酸多西环素在患病虹鳟血浆中的峰浓度为1.19μg/mL,达峰时间为4 h,且血药浓度维持在MIC以上16 h,可以满足虹鳟杀鲑气单胞菌病治疗需要。60 mg/kg剂量单次给药,盐酸多西环素在患病虹鳟血浆、肌肉、肾脏和肝脏中药物浓度维持在MIC以上的时间分别为23、18、23.5和23.5 h,在患病虹鳟血浆、肾脏和肝脏中药物浓度维持在MPC之上的时间分别为6、23.5和23.5 h,此使用剂量既能达到虹鳟杀鲑气单胞菌治疗作用,又能有效防止产生耐药性。