Ovulation induction in jundiá (Rhamdia quelen,Heptapteridae) using carp pituitary extract or salmon GnRH analogue combined with dopamine receptor antagonists

Jundiá (Rhamdia quelen) is an important species for aquaculture in temperate and subtropical climates. In the present study, the results of different forms of GnRH analogue treatments on ovulation in jundiá have been compared with those from treatment with carp pituitary. Seven out of eight females ovulated in groups treated with carp pituitary (4.0 mg kg^?1 BW) and Ovaprim (0.5 mL kg^?1 BW). Injection with sGnRHa (10 μg kg^?1 BW) combined with metoclopramide (20 mg kg^?1 BW) caused a significantly lower rate of ovulation with three out of eight females responding. None of the fish injected with sGnRHa (10 μg kg^?1 BW) alone ovulated. Mean PGSI [(weight of stripped egg mass/BW of the female before stripping) × 100] and mean fertilization rate values were high and similar between treatment groups. The obtained results indicate that in jundiá, there is a strong dopamine inhibitory tone on gonadotropin secretion. The gonadotropin releasing activity of sGnRHa can be potentiated by dopamine receptor antagonists and the combined treatment is effective in inducing ovulation. In this regard, domperidone proved to be more potent than metoclopramide.     

Effect of dietary chitosan on growth performance,haematology, immune response,intestine morphology,intestine microbiota and disease resistance in gibel carp (Carassius auratus gibelio)

A 75‐day experiment was conducted with juvenile gibel carp (Carassius auratus gibelio) (4.80 ± 0.01 g) to evaluate effects of dietary chitosan on fish growth performance, haematology, intestine morphology and immune response. Six isonitrogenous (crude protein: 383 g kg^?1), isolipid (97.5 g kg^?1) and isocaloric (gross energy: 16.7 kJ g^?1) diets were formulated to contain 0, 1800, 4000, 7500, 10 000, 20 000 mg kg^?1 chitosan, respectively. The results showed that the growth was depressed when the fish fed with 10 000 mg kg^?1 chitosan. Serum cholesterol, triglyceride and low‐density lipoprotein decreased in 10 000 and 20 000 mg kg^?1 chitosan. On day 75, blood leucocyte phagocytic activity respiratory burst and alternative pathway of complement haemolytic activity were enhanced in 4000 mg kg^?1 chitosan. The number of goblet cell, intraepithelial lymphocyte of mid‐intestine and microvilli height of distal intestine increased at 4000 mg kg^?1 dietary chitosan. Dietary chitosan modulated intestine microbiota, depressed pathogen bacteria Aeromonas veronii‐like and improved Cellulomonas hominis‐like, Bacillus oceanisediminis‐like and two uncultured bacterium‐like species on day 75. Dietary 7500 and 10 000 mg kg^?1 chitosan enhanced the protection against Aeromonas hydrophila infection. In conclusion, oral administration of dietary 7500 mg kg^?1 chitosan for 75 days is recommended for the survival of gibel carp.     

A tolerance and safety assessment of daidzein in a female fish (Carassius auratus gibelio)

Daidzein is widely used in farmed animals as a dietary additive. However, limited information is available about its use in aquaculture. The effects of daidzein inclusion in the diet of gibel carp was assessed in terms of growth performance, immune response, disease resistance, antioxidant activity, hormone levels, daidzein tissue residues, as well as intestinal and liver morphology. The dietary daidzein inclusion levels were 0, 40, 200 and 400 mg kg^?1 and six replicates of 30 fish were used for each group. No mortality was observed during the 80‐day feeding trial. The growth performance of experimental fish was not significantly affected by dietary daidzein supplementation. However, the non‐specific immune responses, resistance to Aeromonas hydrophila, antioxidant activities, 17β‐oestradiol level, vitellogenin concentration, gonadosomatic index (GSI) and intestinal morphology were significantly affected by dietary daidzein. A dietary dose of 400 mg kg^?1 daidzein significantly decreased the GSI, increased 17β‐oestradiol and vitellogenin concentrations, and impaired the intestinal structure. The daidzein residue in muscle of gibel carp was increased by the high level (400 mg kg^?1) of dietary daidzein. Equol was not detected in fish muscle among all treatments. The present study proved that 40 mg kg^?1 daidzein was safe to be included in diets of gibel carp, and a safety margin of 5 folds of the use‐level (40 mg kg^?1) was determined.     

Protective effects of basil (Ocimum basilicum) ethanolic extract supplementation diets against experimental Aeromonas hydrophila infection in common carp (Cyprinus carpio)

This study evaluated the effects of basil (Ocimum basilicum) leaves extract supplement on growth, blood parameters and resistance to Aeromonas hydrophila in Cyprinus carpio fingerlings. Basil leaves were mixed thoroughly with feed at 0, 100, 200, 400, 800 and 1600 mg kg^?1 of diet and were fed in triplicate group for 2 months. At the end of this period, growth performance and survival were determined. Then fish were challenged intraperitoneally with A. hydrophila and mortalities were recorded up to 10 days post challenge. Results indicated that WBC, RBC, Ht, Hb, total protein, albumin and globulin were higher (P < 0.05) in fish fed diets containing O. basilicum compared with the control. Highest specific growth rate values were observed in 400 mg kg^?1 group. Feed conversion ratio was significantly lower (P < 0.05) in fingerlings fed 400 and 800 mg O. basilicum kg^?1 dry diet. After 10 days post challenge, total protein, WBC, RBC and Hb were significantly higher in 400 mg kg^?1 compared with other groups. These results reveal that a dietary O. basilicum leaves extract of 400 mg kg^?1 fed for 60 days leads to increased growth performance and survival rate as well as improved feeding efficiency in common carp fingerlings rendering them more resistant against infection by A. hydrophila.     

Dietary selenium requirement for on‐growing gibel carp (Carassius auratus gibelio var. CAS III)

A 12‐week growth trial was conducted in a flow‐through system to determine dietary selenium (Se) requirement for on‐growing gibel carp (initial body weight: 76.2 ± 0.05 g, mean ± SEM). Selenomethionine was supplemented to the basal diet to formulate seven semi‐purified diets containing 0.26, 0.58, 0.72, 1.14, 1.34, 1.73 and 2.09 mg Se kg^?1 diet. The results showed that plasma superoxide dismutase (SOD) activity significantly increased when fish were fed with 0.58 mg Se kg^?1 diet (P < 0.05) and then decreased at 2.09 mg Se kg^?1 diet (P < 0.05). Plasma T‐AOC activity was higher in fish fed with 0.72 mg Se kg^?1 diet (P < 0.05) and plasma malondialdehyde (MDA) was higher in fish fed with 0.26 mg Se kg^?1 diet (P < 0.05). When fish were fed 1.14 mg Se kg^?1 diet, hepatic GSH‐Px, T‐AOC, GSH and CAT activities were significantly higher than those fed with 0.26 mg Se kg^?1 diet (P < 0.05). Hepatic superoxide dismutase (SOD) activity was higher at 1.34 mg Se kg^?1 diet (P < 0.05). Fish liver Se concentrations were significantly higher when fed with 0.72 mg Se kg^?1 diet (P < 0.05) and then kept constant when Se ≥ 0.72 mg kg^?1 (P > 0.05). Whole‐body and muscle Se concentrations were higher when fed with 1.34 mg Se kg^?1 diet (P < 0.05) and kept a plateau when Se ≥ 1.34 mg kg^?1 (P > 0.05). In conclusion, based on broken‐line regression of hepatic Se concentrations, hepatic SOD activity and hepatic T‐AOC activity, dietary Se requirements for on‐growing gibel carp was 0.73 mg kg^?1, 1.12 mg kg^?1 and 1.19 mg kg^?1 diet respectively.     

Efficacy of bath and orally administered praziquantel and fenbendazole against Lepidotrema bidyana Murray,a monogenean parasite of silver perch,Bidyanus bidyanus (Mitchell)

We investigated the efficacy of praziquantel (PZQ) and fenbendazole (FBZ), each administered by bath and orally, against the monogenean Lepidotrema bidyana Murray, a gill parasite of the freshwater fish silver perch, Bidyanus bidyanus (Mitchell). PZQ and FBZ were each administered by bath at 10 mg L^?1 for 48 h and on surface‐coated feed pellets at 75 mg kg^?1 per body weight (BW) per day for 6 days. Bath treatments of PZQ and FBZ had an efficacy of 99% and 91%, respectively, against adult L. bidyana. Oral treatments of PZQ and FBZ had an efficacy of 79% and 95%, respectively, against adult L. bidyana. Fish rejected feed pellets surface‐coated with PZQ, suggesting that palatability of surface‐coated PZQ‐medicated feed is poor, which undermined efficacy. In all trials, some juvenile parasites were present on fish after treatment during efficacy assessment, indicating that efficacy may be lower against juvenile parasites or that recruitment occurred post‐treatment, demonstrating that repeat treatments are necessary to effectively control L. bidyana in aquaculture.     

The impaired flesh quality by iron deficiency and excess is associated with increasing oxidative damage and decreasing antioxidant capacity in the muscle of young grass carp (Ctenopharyngodon idellus)

To investigate effects of iron (Fe) on growth, haematological parameters, flesh quality and antioxidant status in muscle, young grass carp (Ctenopharyngodon idella) (292.0 ± 3.2 g) were fed graded levels of Fe (20.7, 38.4, 52.8, 79.3, 98.0 and 120.0 mg kg^?1 diet) for 8 weeks. Per cent weight gain (PWG) and feed intake were improved with Fe levels up to 52.8 mg kg^?1 diet. Serum Fe, erythrocyte counts, haemoglobin (Hb), haematocrit and mean cell haemoglobin increased with optimal Fe levels (38.4–79.3 mg kg^?1 diet) (P < 0.05). The muscle protein and lipid contents were increased by dietary Fe, whereas moisture, liquid loss, shear force and hydroxyproline contents followed opposite trends. Malondialdehyde and protein carbonyl contents in muscle were the lowest in fish fed the 52.8 or 79.3 mg Fe kg^?1 diet, respectively, while superoxide dismutase, catalase, glutathione‐S‐transferase, glutathione peroxidase and glutathione reductase activities, and glutathione content were increased by Fe levels up to 52.8–79.3 mg kg^?1 diet. Results indicated that the optimal Fe improved growth, flesh quality and muscle antioxidant defence of young grass carp. Dietary Fe requirements for PWG, serum Fe and Hb of young grass carp (292–695 g) were 73.5, 72.8 and 69.0 mg kg^?1 diet, respectively.     

Effects of dietary folic acid on growth,antioxidant capacity,non‐specific immune response and disease resistance of juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853)

An 8‐week study was conducted to determine folic acid requirement and its effect on antioxidant capacity and immunity in juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853), followed by a challenge assay with the pathogen Aeromonas hydrophila for 2 weeks. Folic acid was added to a basal diet at seven levels (0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 mg folic acid kg^?1 diet), and a diet free of folic acid and vitamin B₁₂ was also included as a control. Crabs were fed twice daily in 32 tanks with 7.76–8.17 mg oxygen L^?1, 25.0–31.0 °C and 7.5–8.3 pH. Growth and feed efficiency were significantly greater in crabs fed ≥2.0 mg folic acid kg^?1, but not significantly different between crabs fed diets >2.0 mg folic acid. The superoxide dismutase activity and glutathione S‐transferase activity were highest in crabs fed ≥2.0 mg folic acid kg^?1, followed by those fed 0.5 and 1.0 mg folic acid kg^?1, and the control diet. The malondialdehyde content was highest in crabs fed the control diet, followed by those fed 0 mg folic acid kg^?1, and the lowest value occurred in those fed ≥0.5 mg folic acid kg^?1. Phenoloxidase activity and total haemocytes were significantly higher in crabs fed ≥2.0 mg folic acid kg^?1 than other diets. Crabs fed 2.0 mg folic acid kg^?1 had the highest lysozyme, acid phosphatase and alkaline phosphatase activities but the lowest cumulative mortality. The optimum dietary folic acid requirement by E. sinensis was estimated at 2.29–2.90 mg kg^?1 diet.     

Growth,digestive and absorptive abilities and antioxidative capacity in the hepatopancreas and intestine of young grass carp (Ctenopharyngodon idellus Val.) fed graded levels of dietary manganese

To study the effects of manganese on growth performance, digestive and absorptive abilities, as well as the antioxidative capacity in the hepatopancreas and intestine, young grass carp (Ctenopharyngodon idellus Val.) (264 ± 1 g) were fed diets containing graded levels of manganese at 3.65 (control), 8.62, 13.48, 18.24, 22.97 and 27.86 mg kg^?1 diet for 8 weeks. Per cent weight gain (PWG) and feed intake were the poorest in fish fed the basal diet (P < 0.05). The activities of trypsin, lipase and alkaline phosphatase in the intestine were significantly enhanced with dietary manganese level at 13.48 mg kg^?1 diet (P < 0.05). Additionally, in the hepatopancreas and intestine, the protein carbonyl and malondialdehyde contents were the lowest in fish fed the diet with dietary manganese level at 13.48 mg kg^?1 diet (P < 0.05), while the anti‐hydroxyl radical capacities, manganese superoxide dismutase (MnSOD), glutathione peroxidase and glutathione‐S‐transferase activities were significantly enhanced with dietary manganese level at 13.48 mg kg^?1 diet (P < 0.05). Moreover, the catalase activity and glutathione content in the intestine were the highest in fish fed the diet with dietary manganese level at 18.24 mg kg^?1 diet (P < 0.05). These results indicated that optimum dietary manganese promoted growth, enhanced the digestive and absorptive abilities, and improved the antioxidative capacity in young grass carp. Based on the quadratic regression analysis for PWG and intestinal MnSOD activity, the manganese requirements for young grass carp with the initial body weight of 264 g were 16.91 and 18.21 mg kg^?1 diet respectively.     

Stimulatory effect of thyroid hormones improves larval development and reproductive performance in alligator gar (Atractosteus spatula) and spotted gar (Lepisosteus oculatus)

Development of alligator gar (Atractosteus spatula) and spotted gar (Lepisosteus oculatus) larvae was evaluated after exposure of embryos to thyroid hormones (TH) by two different methods of administration. For the first method, alligator gar embryos were placed in a water bath with triiodothyronine (T₃; 1 ppm for 2 h), and control treatment embryos were placed in a water bath without T₃. For the second method, spotted gar adult males and females were injected with different TH during induced spawning: a group was injected with T₃ [20 mg kg^?1 body weight (BW)], a second group with thyroxine (T₄; 20 mg kg^?1 BW), a third group with thyroid‐stimulating hormone (TSH; 4 IU kg^?1BW) and a control group with dimethyl sulfoxide. Both methods resulted in increases in the concentrations of T₃ and T₄ in embryos of both species. An increase in the alkaline enzymatic activity of TH‐treated larvae was observed as well as an increase in the RNA:DNA, RNA:Dry weight and DNA:Dry weight ratios at hatching. Some positive effects of TH application were: a significant increase in the hatching rate of spotted gar larvae from TH‐injected parents and a higher percentage of successful spawns. Evenness of larval sizes and a higher survival rate were observed in alligator gar larvae. Snout development was accelerated by TH treatment in both species.     

Enrofloxacin pharmacokinetics in Takifugu flavidus after oral administration at three salinity levels

The present study was designed to explore the pharmacokinetics of enrofloxacin in Takifugu flavidus at different salinity levels (10‰, 20‰ and 30‰). The concentrations of enrofloxacin in plasma and tissues (kidney, liver and muscle) of T. flavidus after a single oral dose of 10 mg kg^?1 were simultaneously determined using HPLC. The parameters of pharmacokinetics were calculated using non‐compartmental model based on statistic moment theory. The peak concentrations of enrofloxacin were higher and T_max values in plasma, liver and muscle tissues of T. flavidus were lower at the salinity of 20‰ and 30‰ than that of 10‰, except the kidney tissue. These demonstrated the absorption of enrofloxacin was more quickly and more quantity at the high salinity. The elimination half‐life (t_1/2z) of enrofloxacin in the plasma (45.22, 69.91 and 95.45 h) was increasing with the increase in salinity. And the t_1/2z values of enrofloxacin in liver (76.44, 44.21 and 33.48 h) and kidney (212.16, 157.43 and 35.61 h) both decline with the increase in salinity, indicating the elimination of enrofloxacin was faster in liver and kidney but slower in plasma at the high salinity. The content of enrofloxacin in liver was increasing with the increase in salinity, suggesting that salinity affects tissue distribution and metabolism in T. flavidus. In addition, the AUC_0–∞ data of enrofloxacin (kidney > plasma > liver > muscle) at different salinity levels were essentially consistent, and AUC_0–∞ data of kidney were declined with the increase in salinity, supporting that the kidney was the main organ and the role of extent of kidney on excretion was different in different salinity levels.     

Dose‐dependent protective effects of dietary selenium on abalone Haliotis discus hannai Ino against the toxicity of waterborne copper

This study was designed to assess the protective effects of dietary selenium (Se) on abalone Haliotis discus hannai Ino against the toxicity of waterborne copper (Cu). A 60‐day feeding trial was conducted in a static water system for abalone (initial weight: 3.17 ± 0.01 g) exposed to 0.02 mg L^?1 of waterborne Cu. The animals were fed one of the three experimental diets with 0.10, 1.31 and 4.20 mg kg^?1 of Se from Na₂SeO₃·5H₂O respectively. Results showed that the abalone fed 1.31 mg kg^?1 of dietary Se had the lowest Cu concentration in shell, muscle, mantle, gill, hepatopancreas and serum. Meanwhile, the significant lowest contents of malondiadehyde and protein carbonyl in hepatopancreas were also found in the treatment with 1.31 mg kg^?1 of dietary Se (P < 0.05). In addition, this treatment had significant higher glutathione content and thioredoxin reductase activity in hepatopancreas (P < 0.05). However, the activity of Se‐dependent glutathione peroxidase (Se‐GPx) was significantly decreased in the treatment with 4.20 mg kg^?1 of dietary Se (P < 0.05). In this treatment, the protein carbonyl content in hepatopancreas was significantly higher than that in the group with 1.31 mg kg^?1 of dietary Se (P < 0.05). In conclusion, in terms of anti‐oxidation and Cu accumulation, the protective effects of dietary Se on abalone against waterborne Cu were dose‐dependent. The 1.31 mg kg^?1 of dietary Se had this effect, but not 4.20 mg kg^?1 of dietary Se. Moreover, the latter increased the oxidative stress in abalone exposed to the waterborne Cu.     

Bioassay‐guided isolation and identification of active compounds from Macleaya microcarpa (Maxim) Fedde against fish pathogenic bacteria

Four alkaloids (Sanguinarine, 6‐Methoxyl‐dihydro‐chelerythrine, Cryptopine and β‐Allocryptopine) were isolated from aerial parts of Macleaya microcarpa (Maxim) Fedde using bioassay‐guided isolation method, and the inhibitory activity of ethanolic extract, various fractions and these four alkaloids against four fish pathogenic bacteria (Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum and Vibrio harveyi) was assessed in vitro using the agar dilution method and the microdilution assay method respectively. A. hydrophila was the most sensitive strain to all the tested compounds. Minimum inhibitory concentration (MIC) values were lower for sanguinarine against all tested Gram‐negative strains than other three alkaloids, with MIC values of 12.5 mg L^?1 for A. hydrophila and 50 mg L^?1 to other pathogenic bacteria. Followed by 6‐methoxyl‐dihydro‐chelerythrine, which showed considerable antibacterial activity with MIC values of 80 mg L^?1 for A. hydrophila, 100 mg L^?1 for V. harveyi, and 125 mg L^?1 for both V. anguillarum and A. salmonicida. Cryptopine and β‐allocryptopine revealed similar inhibitory activity with MIC values of 100 mg L^?1 for A. hydrophila and 200 mg L^?1 for other three bacterial species. These finding provided evidence that extract, as well as isolated compounds from M. microcarpa might be potential sources novel antibacterial agents for the treatment of fish infectious diseases.     

Dietary administration of natural immunostimulants on growth performance,haematological, biochemical parameters and disease resistance of Asian Sea bass Lates calcarifer (Bloch, 1790)

This study was aimed to address the promising evaluation of Cissus quadrangularis plant (stem) and lipopolysaccharide (LPS from bacteria) supplemented diets on innate immune response in Lates calcarifer fingerlings against Aeromonas hydrophila infection. Fingerlings were fed supplemented diets containing four different concentrations of C. quadrangularis (0.5, 1.0, 1.5 and 2.0 g kg^?1 feed), LPS (25, 50, 75 and 100 mg kg^?1 feed) and control (normal formulated diet) for 60 days. The fish fingerlings fed supplemented diet displayed significant differences (P < 0.05) in specific growth rate (SGR) and relative percentage survival compared to the control group fed without C. quadrangularis and LPS‐supplemented diet. Fingerlings were injected intraperitoneally with 100 μL lethal dose of A. hydrophila containing 1 × 10⁶ CFU g^?1. Supplementation of C. quadrangularis and LPS diet significantly increased biochemical profile such as protein, lipid and carbohydrate content, haematological parameters of L. calcarifer fingerlings in different experimental periods when compared with the control group. Dietary doses of C. quadrangularis and LPS‐supplemented diet significantly influenced growth performance and increased survival rate in L. calcarifer fingerlings against A. hydrophila infection.     

Environmental fate and pharmacokinetics of sulphamethazine in Fenneropenaeus chinensis shrimp production systems after oral administration

The antimicrobial sulphamethazine is widely used in aquaculture for the prevention and treatment of bacterial diseases. Residues of sulphamethazine have been detected in aquatic environments and in edible tissues of aquaculture fish and shrimps at relatively low, but detectable concentrations. Detailed information on the environmental fate and pharmacokinetics of sulphamethazine in aquaculture species is essential to predict possible ecological risks and to provide recommendations on appropriate dosages and withdrawal periods. In this study we investigated the distribution of sulphamethazine in water and sediments of Fenneropenaeus chinensis shrimp ponds treated with 50, 100 and 150 mg kg^?1·bw of sulphamethazine for 5 days and measured the uptake and elimination dynamics of sulphamethazine in different shrimp organs and tissues. Results of the HPLC analysis showed highest sulphamethazine concentrations in shrimp tissues, followed by sediments and water. The rank order of the mean concentrations of sulphamethazine in shrimp tissues and organs was hepatopancreas> plasma≈ stomach> muscle≈ gill≈ intestine> carapace. The results also demonstrated a significant dose‐dependent accumulation of sulphamethazine in the different biological and environmental compartments. Sulphamethazine decreased gradually with the time in all of the three compartments. The mean half‐life of sulphamethazine in sediment and water was 2.15 and 2.17 days respectively. A withdrawal period of 10 days or more is proposed for F. chinensis orally treated with sulphamethazine in order to meet the current food safety standards.     

Immunostimulatory effects of N‐Oxide–Quaternary alkaloid fraction of a marine Chlorophycean macroalga in the striped murrel,Channa striata (Bloch)

N‐Oxide–Quaternary Alkaloid Fraction (NOQAF) of a Chlorophycean macroalga, Caulerpa scalpelliformis (R.Br.) C. Ag f. denticulata (Deaisne) Weber van Bosse (Patent filed) was intraperitoneally administered at different doses (0, 2, 20 or 200 mg kg^?1 body weight) in different groups of Channa striata to assess its effect on the non‐specific immune responses and disease resistance against live virulent Aeromonas hydrophila. A reference positive control [MacroGard (Biotec Pharmacon ASA, Norway) 20 mg kg^?1 body weight] was simultaneously maintained to compare its efficacy. The fraction (NOQAF) has been found to enhance the serum lysozyme, peroxidase, antiprotease and alternate complement activities and the reactive oxygen and nitrogen species production and peroxidase activity by the peripheral blood leucocytes than the control group during the study period. On experimental challenge with live virulent A. hydrophila, maximum RPS values of 88.8 and 87.4 were noted in the groups treated with single dose of 20 mg kg^?1 and double dose of 2 mg kg^?1 of NOQAF respectively. In conclusion, the intraperitoneal administration of the N‐Oxide–Quaternary Alkaloid Fraction (NOQAF) of C. scalpelliformis has been found to significantly enhance the non‐specific immune responses and disease resistance against A. hydrophila in Channa striata.     

Ovulation and spawning induction in Caspian kutum Rutilus frisii kutum by administration of GnRHa and catecholaminergic pharmaceutical compounds with Ovaprim

The acceleration of final oocyte maturation and ovulation is recognized as a principal process in Caspian kutum Rutilus frisii kutum, a commercial and valuable species in Caspian Sea. The aim of this study was to evaluate the effects of catecholaminergic pharmaceutics which include Salbutamol (β₂‐adrenergic receptor agonist), Metoprolol (β₁‐adrenergic receptor antagonist), Clozapine and Olanzapine (the third generation of D₄ and D₂ dopamine receptor antagonists) which can be more efficient than the first and second generations, in combination with Buserelin ([D‐Ser(tBu)⁶,Pro⁹‐NEt]‐GnRHa) and Ovaprim (D‐Ala⁶,Pro⁹‐Net)‐sGnRH+Domperidone on ovulation and spawning induction in Caspian kutum. One hundred eight adult females were injected once with Buserelin Acetate (BUS) 5 μg kg^?1 BW, Ovaprim 0.5 mL kg^?1 BW, Salbutamol Sulphate (SLB) 4 mg kg^?1 BW, Olanzapine (OLZ) 5 mg kg^?1 BW, Clozapine (CZ) 12 mg kg^?1 BW and Metoprolol Tartrate (MTP) 5 mg kg^?1 BW, being divided into 12 groups: group 1, intact (negative control); group 2, Ovaprim (positive control); group 3, OLZ+SLB; group 4, OLZ+MTP; group 5, OLZ+BUS; group 6, CZ+SLB; group 7, CZ+MTP; group 8, CZ+BUS; group 9, OLZ+BUS+SLB; group 10, OLZ+BUS+MTP; group 11, CZ+BUS+SLB and group 12, CZ+BUS+MTP (N = 9). The results showed that the highest mean value in ovulation success, ovulation index, fertilization success, relative fecundity and the number of eggs belonged to Ovaprim treatment. On the other hand, spawning was successful in OLZ+BUS+SLB and CZ+BUS treatments (P < 0.05), whereas it was lower in CZ+MTP, CZ+BUS+MTP and OLZ+BUS than the other treatments. Therefore, it could be concluded that Clozapine and Olanzapine potentiated the effect of Buserelin treatment in ovulation and spawning induction, while Metoprolol blocked the stimulatory effects of GnRHa, Clozapine and Olanzapine. Salbutamol also can amplify stimulatory effect of all mentioned pharmaceutics.     

Enhancement of non‐specific immune responses in common carp,Cyprinus carpio,by dietary carotenoids obtained from shrimp exoskeleton

The immunostimulatory role of carotenoid extract from shrimp processing discards was evaluated by feeding common carp fingerlings with a diet containing carotenoid extract for 21 weeks at 100 and 200 mg kg^?1 astaxanthin levels. Haemoglobin content was significantly (P < 0.05) higher in the blood of fish fed with carotenoid diet (>8.1 g dL^?1) compared with that from fish fed with carotenoid deficient diet (6.86 g dL^?1) and also leukocyte counts were higher (P < 0.05). No differences (P > 0.05) were observed in total serum protein, globulin level and albumin‐globulin ratio, but albumin content was higher (P < 0.05). Respiratory burst activity was significantly (P < 0.05) higher, the serum lysozyme activity almost doubled and the serum bactericidal activity was significantly increased when the fish were fed with diet containing 200 mg kg^?1 of astaxanthin but no significant differences were observed in serum trypsin inhibitory activity. There was a significant (P < 0.05) increase in leukocyte myeloperoxidase activity due to dietary carotenoids. Challenging fish with Aeromonas hydrophila after the feeding period resulted in 50% mortality in the control group while in the group fed with diet containing 100 mg kg^?1 astaxanthin, the mortality rate was 15%. No mortality and even symptoms of infection was not observed in the group fed with diet containing 200 mg kg^?1 of astaxanthin. The study indicated that carotenoid extract from shrimp processing discards can effectively be used as immunostimulants in aquaculture of carps and dietary carotenoids were found to enhance various immune defence mechanisms and also provide protection against the infection of pathogen A. hydrophila.     

Hen egg yolk and skinned krill as possible foods for rearing leptocephalus larvae of Anguilla japonica Temminck & Schlegel

Usual diets for rearing leptocephalus larvae of Japanese eel Anguilla japonica include eggs of the endangered spiny dogfish Squalus acanthias (SE). We investigated the effects of alternative food materials, hen egg yolk (HEY) and exoskeleton‐free (skinned) Antarctic krill (SAK), on the growth and survival of eel larvae. We found that feed comprising whole krill including exoskeleton (WAK) containing higher levels of fluoride (37.89 mg kg^?1) was acutely toxic to eel larvae exposed to this alone. In contrast, extract from SAK containing lower concentrations of fluoride (4.25 mg kg^?1) showed no apparent adverse effects. Growth of larvae fed a mixture of SE and SAK in a feed trial of 58 days [mean body weight (BW), 6.0 mg] was about twofold higher than that of larvae fed a mixture of SE and WAK (3.2 mg) (P < 0.01). A mixture of HEY and SAK also had some dietary benefits for eel larvae, enabling them to survive for up to 58 days and to grow significantly (mean BW, 2.4 mg), compared with their initial weight (mean BW, 0.2 mg) (P < 0.001). Although additional nutritional improvements are needed, the present results suggest that combination diet HEY and SAK may be a good alternative to SE as an effective diet for eel larvae.     

Preliminary success using hydrogen peroxide to treat Atlantic salmon,Salmo salar L., affected with experimentally induced amoebic gill disease (AGD)

Currently, the only effective and commercially used treatment for amoebic gill disease (AGD) in farmed Tasmanian Atlantic salmon is freshwater bathing. Hydrogen peroxide (H₂O₂), commonly used throughout the aquaculture industry for a range of topical skin and gill infections, was trialled in vitro and in vivo to ascertain its potential as an alternative treatment against AGD. Under in vitro conditions, trophozoites of Neoparamoeba perurans were exposed to three concentrations of H₂O₂ in sea water (500, 1000 and 1500 mg L^?1) over four durations (10, 20, 30 and 60 min) each at two temperatures (12 and 18 °C). Trophozoite viability was assessed immediately post‐exposure and after 24 h. A concentration/duration combination of 1000 mg L^?1 for >10 min demonstrated potent amoebicidal activity. Subsequently, Atlantic salmon mildly affected with experimentally induced AGD were treated with H₂O₂ at 12 and 18 °C for 15 min at 1250 mg L^?1 and their re‐infection rate was compared to freshwater‐treated fish over 21 days. Significant differences in the percentage of filaments affected with hyperplastic lesions (in association with amoebae) and plasma osmolality were noted between treatment groups immediately post‐bath. However, the results were largely equivocal in terms of disease resolution over a 3‐week period following treatment. These data suggest that H₂O₂ treatment in sea water successfully ameliorated a clinically light case of AGD under laboratory conditions.