The in‐vitro antibacterial effects of organic salts,chemical disinfectants and antibiotics against pathogens of black disease in fairy shrimp of Thailand

The antibacterial effects of organic salts, chemical disinfectants and antibiotics were evaluated on cultures of Aeromonas hydrophila C03, Aeromonas sobria C26, A. sobria C29, Aeromonas caviae C24 and Acinetobacter sp. SH‐94B, the pathogens that cause black disease found in fairy shrimps (Streptocephalus sirindhornae Sanoamuang et al. (2000) and Branchinella thailandensis Sanoamuang, Saengphan & Murugan) of Thailand. The minimal inhibitory concentrations (MICs) of organic salts (sodium chloride and potassium chloride) and antibiotics (oxytetracycline dihydrate, streptomycin sulphate, kanamycin monosulphate, chloramphenicol and ampicillin) were determined using the agar‐dilution method. The effect of chemical disinfectants (sodium hypochlorite and chlorine dioxide) was evaluated by exposing bacteria to different concentrations of these chemicals for different periods of time. Interestingly, all strains were intrinsically resistant to 0.25–3% sodium chloride and potassium chloride. The effect of sodium hypochlorite was greater than that of chlorine dioxide, and 5–20 μg mL^?1 of sodium hypochlorite was sufficient to inhibit the growth of these bacteria, but the exposure time varied, depending on the bacterial species. Of the antibiotics tested, chloramphenicol and oxytetracycline dihydrate completely inhibited the selected strains. Chloramphenicol showed the highest antibacterial effect against all pathogenic species – the MIC and minimal bactericidal concentration (MBC) ranged from 0.8 to 3.1 μg mL^?1 from 3.1 to 6.25 μg mL^?1, respectively. To achieve control of black disease during cultivation of fairy shrimp, data derived from this study can be used as a basis for further toxicity tests in vivo.     

Nutrient removal efficiency of Hydropuntia cornea in an integrated closed recirculation system with pink shrimp Farfantepenaeus brasiliensis

In this study, we have tested the effect of seaweed stocking density in an experimental seaweed biofilter using the economically important red seaweed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus brasiliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and 8 g fw L^?1). Total ammonia nitrogen (TAN) was the main nitrogen source excreted by F. brasiliensis, with concentrations ranging from 41.6 to 65 μM of NH₄⁺‐N. H. cornea specific growth rates ranged from 0.8 ± 0.2 to 1.4 ± 0.5% day^?1 with lowest growth rates at higher seaweed stocking density (8 g fw L^?1). Nutrient removal was positively correlated with the cultivation densities in the system. TAN removal efficiency increased from 61 to 88.5% with increasing seaweed stocking density. Changes in the chemical composition of the seaweed were analysed and correlated with nutrient enrichment from shrimp effluent. The red seaweed H. cornea can be cultured and used to remove nutrients from shrimp effluents in an integrated multi‐trophic aquaculture system applied to a closed recirculation system. Recirculation through seaweed biofilters in land‐based intensive aquaculture farms can also be a tool to increase recirculation practices and establish full recirculation aquaculture systems (RAS) with all their known associated benefits.     

Retracted: Effect of concentration of the microalga Dunaliella tertiolecta on survival and growth of fairy shrimp,Phallocryptus spinosa Milne Edwards, 1840 (Crustacea: Anostraca)

We investigated the effects of concentration of the microalga Dunaliella tertiolecta on the growth and survival of fairy shrimp, Phallocryptus spinosa. Newly hatched nauplii were stocked into containers, maintained at different concentrations of D. tertiolecta (at 18, 36, 54, 72 and 90 × 10⁶ cells mL^?1). All treatments were in quadruplicate and each replicate was stocked with 100 larvae in a 2‐L cylindrical bowl. We studied the survival and growth of the fairy shrimp after 3, 6, 9, 12 and 15 days of culture. The results indicated significant differences, in terms of growth and survival, of fairy shrimps fed at different algal densities. The highest and lowest growth and survival among the treatments were observed on Day 15, the highest in animals fed at a concentration of 90 × 10⁶ cells mL^?1 and the lowest in animals fed at a concentration of 18 × 10⁶ cells mL^?1. We conclude that the growth and survival of the P. spinosa increased with increasing density of algae, to a threshold level. Within certain concentration limits, the addition of D. tertiolecta substantially improved the performance of larval culture of P. spinosa, suggesting that this fairy shrimp has potential in terms of aquaculture development.     

Immunomodulation of rainbow trout (Oncorhynchus mykiss) fry by bath exposure to a β‐glucan from Euglena gracilis

Early developmental stages of fish mostly depend on innate immune factors for their protection. Augmenting these factors by application of different immunostimulatory substances may be beneficial for rearing and survival of the early life stages of fish. Bath administration of stimulants leads to a uniform exposure of fish independent of feed intake and reduces the individual handling. The present study demonstrates the immunostimulatory effect of β‐glucan (bath exposure) in rainbow trout fry at different dosages and exposure time. Rainbow trout fry (avg. wt. 770 mg; 87 days post hatch) were exposed to three different concentrations of β‐glucan (10, 100 and 1000 μg mL^?1) by bath exposure for 1 and 24 h. Expression of immune related genes from pooled internal organ samples of individual fish were analysed using a real time qPCR assay. Expression of complement factors (C3 and factor B) and acute phase proteins (hepcidin, precerebellin and transferrin) was significantly up‐regulated after 24 h bath stimulation with β‐glucan (100 μg mL^?1). These innate immune factors may play a vital role in clearance of pathogens. The expression of most of genes showed both a dose‐ and time‐dependent response. A medium dose (100 μg mL^?1) induced a significant increase in expression of complement factors and acute phase proteins mainly at 24 h exposure, whereas the highest dose of β‐glucan (1000 μg mL^?1) down‐regulated the expression of most of the studied genes. The result from the present study indicates that β‐glucan bath exposure could be applied for enhancing the innate immune factors even in fry.     

Nutrient composition of fairy shrimp Streptocephalus sirindhornae nauplii as live food and growth performance of giant freshwater prawn postlarvae

Nutritional efficacy of fairy shrimp (Streptocephalus sirindhornae) nauplii, as a live food, was studied for growth performance and survival rate of giant freshwater prawn (Macrobrachium rosenbergii) postlarvae. A feeding experiment was designed with four different feeds: dry commercial feed, fairy shrimp nauplii, Artemia sp. nauplii and adult Moina macrocopa. Results from the nutritional composition revealed that fairy shrimp nauplii had protein and lipid contents of 54.58 ± 2.8 g kg^?1 and 255 ± 2.8 g kg^?1, respectively. The highest value for an individual amino acid in fairy shrimp was lysine (140.7 ± 1.6 g kg^?1). The essential amino acids content in the whole body of the larval prawns was in the range of 66.7–67.5 g kg^?1. Fairy shrimp nauplii had the highest essential amino acid ratio (A/E) of lysine, similarly, in musculature of prawn larvae. Weight gain and specific growth rate of the postlarvae fed with fairy shrimp nauplii were significantly higher than those fed with Artemia nauplii, adult Moina and dry commercial feed. The presented results suggest that S. sirindhornae nauplii can be used as a nutritionally adequate food for freshwater prawn M. rosenbergii postlarvae.     

Lupin kernel meal as fishmeal replacement in formulated feeds for the Whiteleg Shrimp (Litopenaeus vannamei)

Rapidly expanding global aquaculture requires sustainable, local protein sources to supplement the use of fishmeal. Lupin seed meal (Lupinus angustifolius) was tested as sustainable diet component for Whiteleg shrimp (Litopenaeus vannamei). Controlled feeding experiments were conducted in a recirculating aquaculture system for eight weeks. Juvenile shrimps were provided formulated diets containing various levels of lupin meal inclusion (0, 100, 200 and 300 g kg^?1) supplementing the fishmeal component, and a commercial feed as general reference. Shrimp survival, growth, metabolic and immune parameters were analysed. Survival did not differ significantly between groups. Growth performance was significantly impaired in shrimp fed diets containing more than 100 g kg^?1 lupin meal. Lupin meal supplementation did not affect haemolymph protein content, whereas glucose and acylglyceride concentrations varied between treatments and were highest in animals fed the 100 g kg^?1 lupin meal diet. Phenoloxidase activity was highest in shrimp fed 100 g kg^?1 lupin meal diet indicating improved immune status. The present study indicates that low inclusion levels of lupin meal do not cause adverse effects and seem to stimulate the immune system of juvenile L. vannamei.     

Depletion of florfenicol amine in tilapia (Oreochromis sp.) maintained in a recirculating aquaculture system following Aquaflor®‐medicated feed therapy

Aquaflor^® [50% w w^?1 florfenicol (FFC)], is approved for use in freshwater‐reared warmwater finfish which include tilapia Oreochromis spp. in the United States to control mortality from Streptococcus iniae. The depletion of florfenicol amine (FFA), the marker residue of FFC, was evaluated after feeding FFC‐medicated feed to deliver a nominal 20 mg FFC kg^?1 BW d^?1 dose (1.33× the label use of 15 mg FFC kg^?1 BW d^?1) to Nile tilapia O. niloticus and hybrid tilapia O. niloticus × O. aureus held in a recirculating aquaculture system (RAS) at production‐scale holding densities. Florfenicol amine concentrations were determined in fillets taken from 10 fish before dosing and from 20 fish at nine time points after dosing (from 1 to 240 h post‐dosing). Water samples were assayed for FFC before, during and after the dosing period. Parameters monitored included daily feed consumption and biofilter function (levels of ammonia, nitrite and nitrate). Mean fillet FFA concentration decreased from 13.77 μg g^?1 at 1‐h post dosing to 0.39 μg g^?1 at 240‐h post dosing. Water FFC concentration decreased from a maximum of 1400 ng mL^?1 at 1 day post‐dosing to 847 ng mL^?1 at 240 h post‐dosing. There were no adverse effects noted on fish, feed consumption or biofilter function associated with FFC‐medicated feed administration to tilapia.     

Pharmacokinetic/pharmacodynamic properties and P‐glycoprotein expression in pacific white shrimp,Litopenaeus vannamei after oral administration at three dosages of oxolinic acid

The experiments explored the pharmacokinetics (PK) properties of oxolinic acid (OXA) after oral administration at three dosages (10, 30 and 80 mg/kg) via medicated feed in the shrimp. The results showed that the C_max values of 4.31, 14.93 and 16.62 mg/L and AUC_0–∞ values of 92.61, 252.30 and 364.27 mg hr^?1 L^?1 were observed at three OXA dosage groups in the haemolymph respectively. In the hepatopancreas, C_max values of 7.90, 27.23 and 60.51 mg/kg and AUC_0–∞ values of 42.01, 133.06 and 219.06 mg hr^?1 L^?1 were observed at 0.5 hr post administration respectively. In the muscle, C_max values of 1.62, 5.80 and 7.36 mg/kg and the AUC_0–∞ values of 25.64, 98.10 and 134.24 mg hr^?1 L^?1 were observed at 2 hr post administration respectively. In the gills, C_max values of 2.87, 8.08 and 12.12 mg/kg and the AUC_0–∞ values of 51.38, 118.65 and 206.48 mg hr^?1 L^?1 were observed at 4 hr post administration respectively. In addition, the in vitro MIC values of OXA at three dosages against 132 strains of Vibrio were examined and showed that the minimum inhibitory concentration (MIC) values for OXA primarily ranged from 0.15–1.25 µg/ml, including eight strains of Vibrio showing MIC values ≥5 µg/ml. The MIC₅₀ and MIC₉₀ values of 132 strains were 0.62 and 1.25 μg/ml respectively. The AUC_0–24/MIC₉₀ ratios of Vibrio were 140.4 in 30 mg/kg group. Furthermore, the P‐glycoprotein (P‐gp) expression was determined in shrimp tissues after administration to three dosage groups (10, 30 and 80 mg/kg). The results showed that P‐gp expression was up‐regulated in the hepatopancreas (5.36‐, 13.68‐ and 31.06‐fold respectively) compared with the control group.     

Evaluation of flash dried yeast as a nutritional supplement in plant‐based practical diets for Pacific white shrimp Litopenaeus vannamei

Growth and digestibility trials were conducted to evaluate the use of flash dried yeast (FDY) as a supplement in practical shrimp feeds. The six‐week growth trial evaluated the effects of FDY supplementation (0, 10, 20, 40 and 60 g kg^–1) in the plant‐based practical diet on the performances and proximate compositions of juvenile Pacific white shrimp, Litopenaeus vannamei. Final biomass, final mean weight, per cent weight gain (WG), feed conversion (FCR) and protein retention efficiency (PRE) of Pacific white shrimp were not significantly influenced when FDY was added up to 40 g kg^–1 of the diet. However, 60 g kg^–1 FDY supplementation significantly reduced growth, feed utilization and protein retention. Supplementation of FDY in the practical diets of Pacific white shrimp did not affect protein, moisture, lipid, crude fibre, and ash content of whole shrimp body. Apparent digestibility coefficients of energy, protein, and amino acid (AA) for FDY were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy and protein digestibility of FDY were 38.20% and 53.47%, respectively, which were significantly lower than fishmeal (FM) and soybean meal (SBM) that were run at the same time. Most amino acid digestibility of FDY was lowest among the three ingredients tested. Results of this work indicated that energy, protein and amino acid digestibility of FDY are lower compared to SBM and FM, and high levels supplementation (≥60 g kg^–1) of FDY can cause negative effects to the growth response of Pacific white shrimp. Based on these results, further research regarding the effects of the low level inclusion of FDY in practical diets on immune responses of Pacific white shrimp is warranted.     

Nucleotide promotes feed intake and protein utilization via regulating the gene expression of feeding and nitrogen metabolism in juvenile Chinese perch (Siniperca chuatsi)

Nucleotide (NT) could enhance growth, feeding and immunity in higher vertebrate and fish. Chinese perch (Siniperca chuatsi) refuse artificial diet in natural water, whereas the NT might promote its feeding of domestication diet. The present study was designed to investigate the effect of dietary NT on growth, feed intake, feed utilization, body composition, serum biochemistry and nitrogen metabolism in juvenile Siniperca chuatsi. 0, 0.5, 1.0, 1.5, 2.0 and 4.0 g NT kg^?1 diet were supplemented in each diet, respectively. Triplicate groups of Chinese perch (36.21 ± 0.98 g) were fed twice a day to apparent satiation for 8 weeks. The results showed that fish fed with 1.5 g NT kg^?1 diet had the highest weight gain (WG), specific growth rate, feed efficiency, feed intake, protein efficiency ratio and protein retention efficiency. The crude protein content in whole body was highest in fish fed the diet containing 1.5 g NT kg^?1 diet. Dietary NT supplementation significantly increased the neuropeptide Y gene expression and significantly decreased the agouti‐related protein and pro‐opiomelanocortin gene expressions in brain. NT supplementation decreased urea nitrogen content, aspartate aminotransferase (AST) and alanine aminotransferase activities in serum. The hepatic AST activity was increased first and then decreased, and the highest activity was observed in fish fed with 1 g NT kg^?1 diet. Inversely, the activity of glutamate dehydrogenase (GDH) in liver and adenosine 5′‐monophosphate deaminase in muscle decreased first and then increased, and the lowest activity was observed in fish fed with 1.5 g NT kg^?1 diet. Similarly, the gene expression levels of GDH and arginase in liver were lowest in fish fed with 1.5 g NT kg^?1 diet. Based on the broken‐line regression analysis of WG in the present experimental condition, 1.44 g NT kg^?1 diet was the optimum supplementation level in juvenile Siniperca chuatsi.     

Inhibition of Vibrio spp. by 2‐Hydroxyethyl‐11‐hydroxyhexadec‐9‐enoate of Marine Cyanobacterium Leptolyngbya sp. LT19

Seven marine cyanobacteria were isolated from two regions of the Gulf of Thailand and evaluated by the agar diffusion method for antibacterial activity. Inhibitory compound was purified from the crude methanol extract and its structure was elucidated based on extensive spectroscopic analysis, including IR, 1D and 2D NMR spectra as well as mass spectrometry. A novel antimicrobial compound produced by the marine cyanobacterium Leptolyngbya sp. LT19 was identified to be a 2‐hydroxyethyl‐11‐hydroxyhexadec‐9‐enoate which has so far never been reported in microorganisms. Biological assays revealed that this novel compound exhibited antibacterial activities against the Gram‐negative, persistent shrimp pathogens, Vibrio harveyi and V. parahaemolyticus with minimal inhibitory concentration of 250–1000 and 350–1000 μg mL^?1 respectively.     

Successful rearing of whiteleg shrimp Litopenaeus vannamei larvae fed a desiccation‐tolerant nematode to replace Artemia

The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso^®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.     

Effects of Vibrio harveyi on plasma clotting protein (coagulogen) of white shrimp Litopenaeus vannamei

Blood clotting exhibits various important functions, including the prevention of body fluid loss and invasion of pathogens in shrimp. The effects of pathogenic Vibrio harveyi on plasma of white shrimp (Litopenaeus vannamei) in vitro and in vivo were investigated in this study. The clotting protein (coagulogen) in plasma of white shrimp pre‐incubated with extracellular products (ECP) of V. harveyi was found apparently decreased and fast‐migrated in crossed immunoelectrophoresis (CIE) gels. In addition, the coagulogen had been degraded to many low molecular‐weight protein bands in plasma pre‐incubated with ECP on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) gels. When pre‐challenged with bacterial cells and ECP of V. harveyi, the white shrimp began to die at about 30 and 16 h respectively. Moreover, plasma coagulogen was decreased more obvious in shrimp challenged with ECP than that with bacterial cells as visualized in CIE gels, and total plasma protein in both group of shrimp were all decreased. Haemolymph withdrawn from moribund shrimp pre‐challenged with V. harveyi or its ECP was observed unclottable. However, the addition of clotting factors (transglutaminase and/or Ca²⁺) to these unclottable plasma could apparently promote their re‐clotting ability as jelly‐like solid observed in microtubes. The recovery of clotting ability of plasma from moribund shrimp was due to the reformation of coagulogen (200 kDa) after adding the two clotting factors as shown on CIE and SDS‐PAGE gels. The present results suggest that the infection of V. harveyi in white shrimp may not only degrade coagulogen but also influence the presence of transglutaminase and Ca²⁺ ion.     

Strain and dose infectivity of Vibrio parahaemolyticus: the causative agent of early mortality syndrome in shrimp

Diseases of shrimp have contributed to billions of dollars of economic loss in the aquaculture industry. Newly emerging strains of the bacterium Vibrio parahaemolyticus produce a condition in shrimp called early mortality syndrome or acute hepatopancreatic necrosis disease. Three different V. parahaemolyticus strains were evaluated for their respective pathogenicity on shrimp, Litopenaeus vannamei, when the bacterial strains were grown under various laboratory conditions prior to inoculating shrimp. For each trial, feed was inoculated with a known concentration of bacteria and then fed to the shrimp. The early mortality syndrome strain of V. parahaemolyticus was the most lethal resulting up to 100% mortality within 24 h after being introduced to shrimp via a single feeding. The other two strains of Vibrio, one isolated from the environment and the other from a human clinical case, resulted in 0% and 30% mortality within 96 h respectively. The concentration of the early mortality syndrome strain of V. parahaemolyticus that the shrimp were exposed to directly correlated with mortality rate, which allowed for lethal or sublethal short‐term disease challenge assays to be established. Infiltration of haemocytes was also evident in the midgut caeca of shrimp infected with the early mortality syndrome strain of V. parahaemolyticus, which has not been previously reported.     

Pharmacokinetic model of florfenicol in turbot (Scophthalmus maximus): establishment of optimal dosage and administration in medicated feed

The pharmacokinetics of florfenicol (FF) in turbot (Scophthalmus maximus) was studied after single intravenous (10 mg kg⁻¹) and oral (100 mg kg⁻¹) administration. The plasma concentration–time data of florfenicol were described by an open one‐compartment model. The elimination half‐life (t_1/2) was estimated to be 21.0 h, and the total body clearance, Cl, was determined as 0.028 L kg h⁻¹. The apparent volume distribution (V_d) was calculated to be 0.86 L kg⁻¹ and the mean residence time (MRT_iv) was 30.2 h. Following oral administration, the maximum plasma concentration (C_max) of 55.4 μg mL⁻¹ was reached at 12 h (T_max). The absorption constant (k_a) was 0.158 h⁻¹. The bioavailability was estimated to be 57.1%. The low bioavailability observed at higher doses was explained by the saturation of the mechanisms of absorption. The drug absorption process was limited by its inherent low solubility, which limited the amount of available FF absorbed in the gastrointestinal tract. Based on the pharmacokinetic data, an optimal dosing schedule for FF administration is hereby provided. Based on the minimum inhibitory concentration found for susceptible strains of Aeromonas salmonicida, oral FF administration of first, an initial dose of 30 mg FF kg⁻¹, followed by 6 maintenance doses at 18 mg kg⁻¹/daily could be effective against furunculosis in turbot.     

Gill histopathological characteristics of Caspian roach (Rutilus rutilus caspicus) fingerlings treated with potassium permanganate and formalin

The aim of this study was to determine the gill histopathological characteristics of Caspian roach (Rutilus rutilus caspicus) fingerlings exposed to different concentrations of potassium permanganate (PM) and formalin (FO). The fish were exposed to different PM and FO concentrations over different periods: 1 ppm PM for 24 h (1‐P24), 2 ppm PM for 24 h (2‐P24), 5 ppm PM for 0.5 h (5‐P0.5), 10 ppm PM for 0.5 h (10‐P0.5), 10 ppm FO for 24 h (10‐F24), 20 ppm FO for 24 h (20‐F24), 40 ppm FO for 0.5 h (40‐F0.5) and 80 ppm FO for 0.5 h (80‐F0.5). After exposure, gill samples were collected for histological examination. The most frequent gill histopathological symptoms were hyperplasia and epithelial lifting. The order of the gill injury index (I_g.i) among the treatments was as follow: 1‐P24, 2‐P24 < 5‐P0.5, 40‐F0.5 < 10‐F24 < 10‐P0.5, 20‐F24, 80‐F0.5. Comparing the two agents, it is concluded that there is no significant difference in the gill damages between the agents during the short‐bath treatments. However, PM causes less pathological symptoms than FO during the long‐bath treatments. Comparing the bath durations, the agents showed different behaviours. PM‐treated fish showed significantly lower gill damage during the long‐bath compared to the short‐bath treatment; whereas, pathological symptoms of FO‐treated fish was dose‐dependent for each exposure period, separately. Overall, exposure of Caspian roach to PM, at the concentrations recommended for long bath, resulted in milder gill damages compared to FO.     

Effects of dietary astaxanthin on growth,antioxidant capacity and gene expression in Pacific white shrimp Litopenaeus vannamei

Pacific white shrimp Litopenaeus vannamei (1050 individuals with initial weight of 1.01 ± 0.001 g) were fed either control diet or one of six dietary astaxanthin (AX) concentration (25, 50, 75, 100, 125 and 150 mg kg⁻¹) diets for 56 days in 35 tanks (30 shrimp per tank). After 56 days of culture, shrimp‐fed AX125 and AX150 diets had higher (P < 0.05) weight gain, specific growth rate, total antioxidant status and lower (P < 0.05) superoxide dismutase (SOD), catalase (CAT) than shrimp fed control diet. After low dissolved oxygen stress for 1 h, survival rate of shrimp fed AX75, AX100, AX125 and AX150 diets was higher (P < 0.05) than that of shrimp fed control diet. Hypoxia inducible factor‐1α (HIF‐1α), cytosolic manganese superoxide dismutase (cMnSOD) and CAT mRNA expression levels of shrimp fed seven diets were significantly down‐regulated under hypoxia than under normoxia, but their expression levels were higher under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet. About 70‐kDa heat‐shock protein (Hsp70) mRNA expression level of shrimp fed seven diets was significantly up‐regulated under hypoxia than under normoxia, but its expression level was lower under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet.     

Antibiotics,Penicillin and Sreptomycin improve semen quality indices of endangered Caspian brown trout,Salmo trutta caspius (Kessler, 1870) during in vitro short‐term storage

In this study, we examined the effects of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate on semen quality indices of endangered caspian brown during 12 days short‐term storage at 4°C. Twenty‐four millilitre semen samples with good quality were considered for the experiment. The semen samples were then stored in the presence and absence of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate. The semen quality parameters including percentage and duration of sperm motility were measured 0, 3, 6, 9 and 12 days after storage. In the antibiotic receiving group, the values of percentage and duration of sperm motility reduced 3 and 6 days after storage respectively and reduced to lowest levels at day 12. In the antibiotic‐free group, the duration and percentage of sperm motility decreased significantly after 3 days of storage and reached to lowest values at day 12. Also, percentage and duration of sperm motility in each storage time were significantly higher in the antibiotic receiving group than in the antibiotic‐free group. The overall values of percentage and duration of sperm motility for all storage periods were higher in the antibiotic receiving group than in the antibiotic‐free group. In conclusion, our results demonstrated that 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate improves the viability of caspian brown trout during short‐term storage.