Glycemic response after glucose oral administration of wild juvenile red grouper <Emphasis Type="Italic">Epinephelus morio</Emphasis> fed two different diets

Epinephelus morio is a large carnivorous species of the Caribbean Sea under reproduction in captivity and nutritional physiology. A diet with raw cornstarch (RCS) was compared to a basal diet without starch (basal) to measure plasma glucose, liver glycogen, and intermediary metabolism. Glucose level did not change (p > 0.05) whereas liver glycogen was significantly higher in fish fed the RCS diet (137.2 ± 14.5 mg g^?1) than in fish fed the basal diet (87.4 ± 14.5 mg g^?1). Oral glucose administration (170 mg glucose per 100 g body weight) yielded a slight change; two peaks of plasma glucose were recorded with basal (5.6 mM L^?1) 2 h after oral administration and at 12 h (6.4 mM L^?1). After 24 h, with 1.7 mM L^?1, fish returned to initial stage (2.4 mM L^?1). RCS diet produced the highest level (6.3 mM L^?1) 2 h after oral administration; lowest level observed at 24 h after oral administration (1.0 mM L^?1). A significant effect was detected with the presence or absence of dietary carbohydrates (CBH) on hepatic fructose 1,6-bisphosphatase and pyruvate kinase activity. Grouper used two strategies to maintain glucose homeostasis: CBH present in the diet oriented towards gluconeogenesis, whereas no dietary CBH enhanced glycolytic route to liberate glucose and increase liver glycogen.     

Transferability of oxytetracycline (OTC) from feed to carp muscle and evaluation of the antibiotic effects on antioxidant systems in liver and kidney

Oxytetracycline (OTC) is employed in fish farms to contest or prevent bacterial infections. We simulated an OTC treatment at therapeutic level (75 mg kg^?1) and at higher doses (150, 300 mg kg^?1) for 10 days. A withdrawal period of 10 days was considered for treated carp, carrying out the same chemical and biochemical analyses (total glutathione, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase and malondialdehyde). The aim was to obtain data related to the carryover in muscle and on variations in the antioxidant indicators in liver and kidney. The OTC residual levels in muscle showed a dose–response relationship. After 10 days of treatment at the recommended dose (75 mg kg^?1), the mean value in muscle was 295 μg kg^?1. After 10 withdrawal days, residues in all treated groups were not entirely eliminated by fish. Residues of recommended 75 mg kg^?1 OTC dose were lower than the maximum permitted by EEC regulation: 100 μg kg^?1. Disturbance in the antioxidant systems in liver and kidney was recorded in (150, 300 mg kg^?1) carp, as well as during the withdrawal period. A lowered superoxide dismutase activity and higher levels of catalase, glutathione peroxidase, glutathione reductase and glutathione were evaluated in liver, while in kidney only higher malondialdehyde and glutathione S-transferase concentrations were recorded for 300 mg kg^?1 dose. The therapeutic OTC dose exerted lower effects, and only in liver, enhancement of GPx and GR activities was recorded. After the withdrawal period, altered antioxidant responses in tissues were restored for all three OTC doses.     

Effects of tank color on the growth,stress responses,and skin color of snakeskin gourami (<Emphasis Type="Italic">Trichogaster pectoralis</Emphasis>)

The effects of tank color on the growth, stress responses, and skin color of snakeskin gourami (Trichogaster pectoralis) were investigated in this study. Fish with initial body weights of 5.03±0.00 g were reared in five experimental tank colors (white, red, green, blue, and black) for 8 weeks. Each tank color was tested in triplicate with an initial stocking density of 15 fish per tank. Fish were fed with commercial sinking pellets at 4% of the average body weight per day. Growth performance, feed utilization efficiency, stress indicators (hematocrit, blood glucose, plasma cortisol levels), and skin color parameters were investigated. The fish reared in blue tanks had a significantly higher average final body weight (9.73?±?0.14 g) and significantly lower average feed conversion ratio (3.42?±?0.12) than the fish reared in black tanks (P?<?0.05). The fish reared in black tanks exhibited higher average hematocrit (36.63?±?1.11%), blood glucose (48.33?±?1.45 mg dL^?1), and plasma cortisol (9.00?±?0.56 μg dL^?1) levels than those reared in the other tank colors. However, the blood glucose levels in only the fish reared in black tanks were significantly higher than those in the fish reared in the other tank colors. The fish skin color ranged from very pale (high skin lightness) in the white tanks to very dark (low skin lightness) in the black tanks, and 80% of the variation in skin lightness were explained by the tank lightness. The use of a blue tank resulted in normal skin color; hence, blue tanks will not affect the customer acceptance of the fish. Our study revealed that blue is the most appropriate tank color for culturing snakeskin gourami.     

Physiological responses associated with capture and crowding stress in matrinxãBrycon cephalus (Gunther, 1869)

The dynamics of plasma cortisol, blood glucose, plasma chloride and liver glycogen were investigated in matrinxã (Brycon cephalus) submitted to capture and various periods of crowding. A total of 400 fish (700±22 g weight) were distributed in four ponds divided into four 50‐m² squares (25 fish/square, 350 g L^?1), where they were acclimated for 30 days. On the sampling day, after 24 h without food, all fish from three squares were transferred to the fourth square. Six fish were sampled before the procedure (control group, zero time) and 1, 3, 6 and 24 h after the capture and crowding. Each sampling was performed in a different pond to prevent additional stress. Fish were anaesthetized and blood and liver collected for biochemical analysis. Water temperature, pH, dissolved oxygen, alkalinity, ammonia and nitrite levels were within acceptable levels for matrinxã rearing. Slight but not significant increases were verified in plasma cortisol and blood glucose levels, as were decreases in plasma chloride and liver glycogen levels. The results suggest that matrinxã is highly tolerant to the procedures of capture and short‐term crowding.     

Investigation of the nutritional requirements of Australian snapper Pagrus auratus (Bloch & Schneider 1801): digestibility of gelatinized wheat starch and clearance of an intra-peritoneal injection of d-glucose

Two experiments were performed to investigate the digestibility and utilization of carbohydrate sources by Australian snapper Pagrus auratus. In the first experiment, snapper of two different size classes (110 and 375 g) were fed a reference diet containing no starch (REF) or diets containing 150 (PN15), 250 (PN25), 350 (PN35) or 450 g kg^?1 (PN45) of 100% gelatinized wheat starch to investigate the interactive effects of fish size and starch inclusion level on apparent organic matter (OM) or gross energy (GE) digestibility (ADC), post‐prandial plasma glucose concentration, hepatosomatic index (HSI) and liver or tissue glycogen content. A second experiment used a 72 h time course study to investigate the ability of larger snapper (300–481 g) to clear an intra‐peritoneal injection of 1 g d ‐glucose kg^?1 body weight (BW). Organic matter and GE ADCs declined significantly in both fish sizes as the level of starch increased (PN45energy small fishenergy large fish). There was no interaction between fish size and inclusion level with respect to GE or OM ADCs. Gross energy ADC for both sized fish was described by the linear function GE ADC=104.97 (±3.39)–0.109 (±0.010) × inclusion level (R²=0.86). Hepatosomatic index, liver and muscle glycogen concentrations were significantly elevated in both small and large snapper‐fed diets containing gelatinized starch compared with snapper fed the REF diet. Three‐hour post‐prandial plasma glucose concentrations were not significantly affected by fish size, inclusion level or the interaction of these factors (REF=PN15=PN25=PN35=PN45), and ranged between 1.60 and 2.5 mM. The mean±SD resting level of plasma glucose (0 h) was 2.4±1.1 mM. Circulating levels of plasma glucose in snapper peaked at 18.9 mM approximately 3 h after intra‐peritoneal injection and fish exhibited hyperglycaemia for at least 12–18 h. There were no significant differences between the plasma glucose concentrations of snapper sampled 0, 18, 24, 48 or 72 h after injection (0=18=24=48=72<12< 1<3=6 h), indicating snapper required almost 18 h to regulate their circulating levels of glucose to near‐basal concentrations. Australian snapper are capable of digesting moderate levels of gelatinized wheat starch; however, increasing the dietary content of starch resulted in a reduction in OM and GE digestibility. Smaller snapper appear to be less capable of digesting gelatinized starch than larger fish, and levels above 250 and 350 g kg^?1 of diet are not recommended for small and large fish respectively. Snapper subjected to an intra‐peritoneal injection of d ‐glucose have prolonged hyperglycaemia; however, the post‐prandial response to the uptake of glucose from normally digested gelatinized starch appears to be more regulated.     

Effects of hormonal manipulation on stress responses in male and female broodstocks of pikeperch Sander lucioperca

This study was designed to determine the effects of hormonal manipulation on stress responses in female and male pikeperch. Two-year-old cultured female and male broodstocks with an average weight of 337.4 ± 20.1 (mean ± SE; n = 16) and 318.7 ± 15.1 g (n = 16), respectively, were randomly allocated into four hormonal treatments each containing 4 fish. Two sexual groups of 16 fish for each gender were considered. Sexually mature male and female pikeperch were injected with either physiological saline solution (as control group), common carp pituitary extract (CPE), human chorionic gonadotropin (hCG) and or luteinizing hormone-releasing hormone analog (LHRHa₂). The blood samples were taken before hormonal injection and after ovulation and spermiation. Then the plasma levels of stress indices (cortisol, glucose, and lactate) were determined. The results showed that all CPE-, HCG-, and LHRHa_2- injected males produced sperm. In females treated with CPE and hCG, three of four ovulated, but none of LHRHa_2- and saline-injected fish spawned. Significant changes in cortisol, glucose, and lactate levels were observed among the females injected with different hormones. Plasma cortisol and glucose levels increased significantly in males injected with CPE and females injected with hCG, but no significant change was observed in lactate levels before and after hormonal induction. Comparison of two sexes revealed significant differences in glucose levels for females in some groups before injection, while CPE-injected sexes showed significant changes in cortisol and lactate concentrations. The results indicated that the induction of ovulation or spermiation stimulated stress responses especially in female pikeperch, and therefore, all the procedures should be made to minimize the disturbance during the artificial spawning.     

Growth,hematological and biochemical indices of common carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis> fed diets containing corn gluten meal

The effects of replacing fish meal (FM) with corn gluten meal (CGM) on growth and physiological performance were evaluated in common carp (Cyprinus carpio). Six experimental diets were formulated by substituting 0 (control), 20, 40, 60, 80, and 100% CGM protein for FM protein. The concentrations of dietary protein in the experimental diets were 27.8–29% and the P:E ratios were 14.7–15.46 mg/kJ. Eighteen fish with an initial weight of 13.5?±?0.1 g were allocated to each of 18 circular tanks (450 L) to give triplicate groups for each dietary treatment. The fish were fed to satiation for 8 weeks. At the end of the feeding trial, growth indices, body proximate composition, and hematological and biochemical parameters were measured. Blood samples were taken from six fish in each tank. Final weight and total length were significantly higher in fish fed 100% CGM (27.8?±?1.2 g and 11.9?±?0.3 cm) than for those fed the control (22.7?±?1.4 g and 10.9?±?0.5 cm) or 20% CGM (22.3?±?1.2 g and 11?±?0.4 cm) diets. No effect of FM replacement by CGM was observed for condition factor or hepatosomatic index (P?>?0.05). The highest value of protein productive value (14.31?±?0.65) was observed in fish fed 20% CGM (P?<?0.05). There were no significant differences in percentage body moisture and fat, but percentages of protein and ash were significantly different among experimental groups; the highest values of protein (15.6?±?0.24%) and ash (3.01?±?0.26%) were recorded in fish fed 40% CGM. For hematological parameters, the highest number of white blood cells (4.1?±?0.1?×?10³ mm^?3) was observed in fish fed 100% CGM (P?<?0.05). In addition, the highest hematocrit (42.1?±?0.7%) and triglyceride (294.11?±?23.82 mg dl^?1) were seen in fish fed the diet containing 40% CGM, while 80% CGM gave the highest cholesterol level (204.44?±?9.0 mg dl^?1; P?<?0.05). Replacement of FM with CGM had no negative effects on growth and physiological parameters of common carp fingerlings in this short (8 weeks) trial, suggesting that it may be feasible to replace FM with CGM in diets formulated for juvenile common carp.     

Cortisol is responsible for positive and negative effects in the ovarian maturation induced by the exposure to acute stressors in Nile tilapia, Oreochromis niloticus

The aim of the present study was to evaluate the effect of acute stress and cortisol injection on oocyte final maturation process in female Nile tilapia (Oreochromis niloticus). Handling followed by a prophylactic treatment (0.3?mL?L^?1 H₂O₂, 5?g?L^?1 NaCl solution during 30?min) and an environmental change (transfer from a 2?m³ fibreglass square tank to 50?L aquaria) were used as acute stressors and compared to a single cortisol injection (0.5 or 5?mg?kg^?1 body weight). For both acute stress and cortisol injection (0.5?mg?kg^?1 body weight), serum cortisol level was significantly increased from 2.3 to 134.1?ng?mL^?1 1?h post-stress/injection and returned to a resting basal value 24?h after the stress/injection. In fish injected with 5?mg?kg^?1 body weight cortisol, mean serum cortisol level reached a peak up to 2500?ng?mL^?1 1?h after injection. 63?% of the females (mean body weight: 242?±?4?g) submitted to the acute stress ovulated within 72?h after the stress. In the same way, cortisol injection (5?mg?kg^?1 body weight) at the 10th day of the maturation cycle led to a twofold reduction of the time before ovulation compared to vehicle injected control fish. Relative and total fecundity were significantly decreased in females submitted to an acute stress or cortisol injected at 5?mg?kg^?1 body weight, but not fertilization or hatching rates. In conclusion, acute stress and cortisol induction exert both positive and negative effects on the final reproductive process in O. niloticus, and cortisol is the endocrine mediator causing these changes.     

Fat deposition pattern and mechanism in response to dietary lipid levels in grass carp, <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>

This study aimed to evaluate the fat deposition pattern and lipid metabolic strategies of grass carp in response to dietary lipid levels. Five isonitrogenous diets (260 g kg^?1 crude protein) containing five dietary lipid levels (0, 20, 40, 60, 80 g kg^?1) were fed to quadruplicate groups of 15 fish with initial weight 200 g, for 8 weeks. The best growth performance and feed utilization was observed in fish fed with lipid level at 40 g kg^?1. MFI and adipose tissue lipid content increased with increasing dietary lipid level up to 40 g kg^?1, and higher lipid level in diet made no sense. Fish adapted to high lipid intake through integrated regulating mechanisms in several related tissues to maintain lipid homeostasis. In the present study, grass carp firstly increased PPARγ and CPT1 expressions in adipose tissue to elevate adipocyte differentiation and lipolysis to adapt to high lipid intake above 40 g kg^?1. In liver, fish elevated hepatic lipid uptake but depressed biosynthesis of hepatic FAs, resulted in no difference in HSI and liver lipid content among the groups. Only in muscle, fish showed a significant fat deposition when the lipid intake above 40 g kg^?1. The excess lipid, derived from enhanced serum TC and TG contents, was more likely to induce deposition in muscle rather than lipid uptake by adipose tissue in grass carp fed with high dietary lipid, indicating the muscle of grass carp might be the main responding organ to high lipid intake.     

Effects of chromium picolinate supplementation on growth,body composition,and biochemical parameters in Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

A feeding trial was conducted to evaluate the effects of chromium picolinate (Cr-Pic) on growth performance, body composition, and biochemical parameters in Nile tilapia Oreochromis niloticus. Five experimental diets were formulated with high-protein diet (HP), low-protein diet (LP), and LP + 0.6, 1.2, or 1.8 mg kg^?1 Cr, respectively. Each diet was randomly assigned to four replicate groups of 30 fish per aquarium in a water-circulated rearing system for 60 days. Dietary 1.2 or 1.8 mg kg^?1 Cr inclusion significantly affects the final body weight, weight gain rate, specific growth rate, feed efficiency rate, and protein efficiency ratio of tilapia compare to the LP diet. The Cr inclusion significantly decreased the content of blood urea nitrogen and the blood glucose level generally with increasing Cr inclusion levels. The Cr content of gill tissue was higher than that of back muscle in all treatments, and the addition of 1.2 or 1.8 mg kg^?1 Cr significantly enhanced the Cr contents of back muscle. The cold stress test results showed that adding Cr significantly enhanced the serum T3 concentration and reduced the activity of serum creatine kinase and the serum cortisol level. These results indicated that the supplementation of chromium picolinate can improve the growth performance and reshape the serum protein and carbohydrate metabolism profile and has the potentiality to alleviate the detrimental effects of cold stress in Nile tilapia. The low-protein diet with 1.8 mg kg^?1 Cr obtained the same growth performance as the high-protein diet.     

草鱼、银鲫和青鱼捕捞后的应激反应

分别评价了捕捞对草食性(草鱼)、杂食性(银鲫)和肉食性(青鱼)鲤科鱼类血液指标(血浆史质醇、葡萄糖和乳酸浓度)、肝糖原含量和两种肝脏糖酵解酶(己糖激酶和丙酮酸激酶)活性的影响。结果显示:草鱼、银鲫和青鱼捕捞后血浆史质醇、葡萄糖和乳酸浓度均显著升高;草鱼和青鱼捕捞后2 h时肝糖原含量呈下降趋势,但银鲫捕捞前、后肝糖原含量未出现显著变化;捕捞前、后青鱼血糖浓度显著高于草鱼和银鲫。银鲫肝糖原含量显著高于草鱼和青鱼,其捕捞后血浆葡萄糖和乳酸浓度增加幅度较小,这意味着捕捞后银鲫应激反应强度相对较低。草鱼和银鲫捕捞后肝脏己糖激酶和丙酮酸激酶活性未发生显著变化,青鱼捕捞后2 h己糖激酶活性显著下降,这意味着捕捞应激后血糖升高未导致草鱼、银鲫和青鱼的肝脏糖酵解酶活性增强。     

Different effects of low- and high-dose waterborne zinc on Zn accumulation,ROS levels,oxidative damage and antioxidant responses in the liver of large yellow croaker <Emphasis Type="Italic">Pseudosciaena crocea</Emphasis>

The aim of the present study was to assess survival rate, Zn accumulation, reactive oxygen species (ROS) levels, oxidative damage and antioxidant responses after Zn exposure (2 and 8 mg L^?1 Zn) at different exposure times (6, 12, 24, 48 and 96 h) in the liver of large yellow croaker. Survival rate was reduced at 96 h, and hepatic Zn content increased during 24–96 by 8 mg L^?1 Zn. In the 2 mg L^?1 Zn group, no fish died and the increase in Zn content merely occurred at 96 h. Exposure to 8 mg L^?1 Zn induced accumulation of ROS, lipid peroxidation and protein carbonylation during the late stage of exposure. In contrast, exposure to 2 mg L^?1 Zn did not result in oxidative damage, which may result from the up-regulation of antioxidant defenses. Although exposure to 8 mg L^?1 Zn increased activities and mRNA levels of antioxidant enzymes during the early stage of exposure, including Cu/Zn–SOD, Mn–SOD, CAT, GPx and GR, the activities of these enzymes except Cu/Zn–SOD were inhibited at 96 h. Furthermore, a sharp increase in Nrf2 expression was observed in fish exposed to 8 mg L^?1 at 6 and 12 h, and 2 mg L^?1 at 12 h and 24 h, suggesting that Nrf2 was required for the protracted induction of these genes. The late increase in Keap1 expression may support its role in switching off the Nrf2 response. In conclusion, the present study demonstrated different effects of low- and high-dose waterborne Zn on antioxidant responses, which could contribute to the understanding of antioxidant and toxic roles of zinc on a molecular level.     

Effects of dietary <Emphasis Type="Italic">myo</Emphasis>-inositol on growth,chemical composition and plasma chemistry of Amur sturgeon <Emphasis Type="Italic">Acipenser schrenckii</Emphasis>

The present study was conducted to demonstrate the dietary myo-inositol requirement and its effects on the growth, proximate composition and blood chemistry of Amur sturgeon (Acipenser schrenckii). Triplicate groups of 30 fish (initial weight 11.90?±?0.12 g) were fed different diets containing graded levels of myo-inositol (28.75, 127.83, 343.83, 565.81, 738.15 and 936.28 mg kg^?1) until satiation for 56 days. The fish were weighed after a 24-h fast, and six fish were used for whole body composition analysis. Further, the liver and muscle were sampled from another six fish for lipid analysis. The blood and liver were sampled from the remaining six fish for haematology and fatty acid analysis. The weight gain of fish increased with myo-inositol content, from the 28.75- to 343.83-mg kg^?1 myo-inositol treatment groups, and then stabilised. The liver lipid content and hepatosomatic index decreased significantly from 21.91 to 19.14% and from 3.20 to 2.76% with increased dietary myo-inositol supplementation, respectively. The whole body lipid content generally decreased from 6.33 to 5.55%. The content of liver-saturated fatty acids decreased significantly (28.13%) in the 936.28-mg kg^?1 treatment group. The content of plasma non-esterified fatty acids increased with the increase in dietary myo-inositol supplementation from 0.77 to 1.17 mmol L^?1, whereas the content of triglycerides significantly decreased from 4.62 to 3.28 mmol L^?1. In conclusion, the optimum myo-inositol requirement was found to be 336.1 mg kg^?1, based on weight gain in a two-slope quadratic broken-line model.     

Effects of dietary amylose/amylopectin ratio on growth performance,feed utilization,digestive enzymes,and postprandial metabolic responses in juvenile obscure puffer Takifugu obscurus

The effect of dietary amylose/amylopectin (AM/AP) ratio on growth, feed utilization, digestive enzyme activities, plasma parameters, and postprandial blood glucose responses was evaluated in juvenile obscure puffer, Takifugu obscurus. Five isonitrogenous (430 g kg^?1 crude protein) and isolipidic (90 g kg^?1 crude lipid) diets containing an equal starch level (250 g kg^?1 starch) with different AM/AP ratio diets of 0/25, 3/22, 6/19, 9/16 and 12/13 were formulated. Each experimental diet was fed to triplicate groups (25 fish per tank), twice daily during a period of 60 days. After the growth trial, a postprandial blood response test was carried out. Fish fed diet 6/19 showed best growth, feed efficiency and protein efficiency ratio. Hepatosomatic index, plasma total cholesterol concentration, liver glycogen and lipid content, and gluconokinase, pyruvate kinase and fructose-1,6-bisphosphatase activities were lower in fish fed highest AM/AP diet (12/13) than in fish fed the low-amylose diets. Activities of liver and intestinal trypsin in fish fed diet 3/22 and diet 6/19 were higher than in fish fed diet 9/16 and diet 12/13. Activities of liver and intestinal amylase and intestinal lipase, and starch digestibility were negatively correlated with dietary AM/AP ratio. Fish fed diet 3/22 and diet 6/19 showed higher plasma total amino acid concentration than fish fed the other diets, while plasma urea nitrogen concentration and activities of alanine aminotransferase and aspartate aminotransferase showed the opposite trend. Equal values were found for viscerosomatic index and condition factor, whole body and muscle composition, plasma high-density and low-density lipoprotein cholesterol concentrations, and activities of lipase and hexokinase and glucose-6-phosphatase in liver. Postprandial plasma glucose and triglyceride peak value of fish fed diet 12/13 were lower than in fish fed the low-amylose diets, and the peak time of plasma glucose was later than in fish fed the other diets. Plasma glucose and triglyceride concentrations showed a significant difference at 2 and 4 h after a meal and varied between dietary treatments. According to regression analysis of weight gain against dietary AM/AP ratio, the optimum dietary AM/AP ratio for maximum growth of obscure puffer was 0.25. The present result indicates that dietary AM/AP ratio could affect growth performance and feed utilization, some plasma parameters, digestive enzyme as well as hepatic glucose metabolic enzyme activities in juvenile obscure puffer.     

Effect of thiamine injection on growth performance,hematology and germinal vesicle migration in sterlet sturgeon Acipenser ruthenus L.

The present study aimed to investigate the effect of thiamine on growth, hematological, egg thiamine content and oocyte nucleus migration indices in sterlet sturgeon (Acipenser ruthenus). A total of 45 female fish (698.6 ± 8.9 g) were distributed in nine fiberglass tanks with three treatments (each in three replicates). Experimental fish were fed once a day with practical diet supplemented with 1 g kg^?1 amprolium hydrochloride (as the antithiamine) for 5 months before spawning. Thiamine hydrochloride was injected to fish with one of three doses at 0, 5 and 50 mg kg^?1 body weight (BW) at three different stages. At the end of each month, fish were weighed and growth parameters such as weight gain, specific growth rate, feed efficiency and final weight were determined. At the end of the 5-month period, hematological parameters and egg thiamine content were measured. The results showed no significant differences in terms of growth performance. Hemoglobin, number of red blood cells and white blood cells were not significantly different among the treatments, but hematocrit was significantly higher in fish injected with 5 mg kg^?1 BW thiamine. The mean corpuscular volume and mean corpuscular hemoglobin were not significantly different, but lower value of mean corpuscular hemoglobin concentration was observed in fish injected with 5 mg thiamine. Percentage of lymphocytes, neutrophils, eosinophils and monocytes were not significantly different among treatments. The results of the germinal vesicle migration index at different stages showed no significant differences in different groups. Results showed that free thiamine, thiamine pyrophosphate and total thiamine in eggs significantly increased at 50 mg kg^?1 injection dose compared with the control, but no significant different was found in thiamine monophosphate. The results revealed that thiamine injection to sterlet broodstocks has positive accumulation in egg thiamine content and some hematological parameters but have no effect on growth and ovarian maturation. We conclude that thiamine can affect some physiological features of broodstock, which needs to be specified in further studies.     

Betanin attenuates carbon tetrachloride (CCl4)-induced liver injury in common carp (Cyprinus carpio L.)

This study investigates the protective effect of betanin against liver injury induced by carbon tetrachloride (CCl₄) in common carp (Cyprinus carpio L.). The fish were treated with 1, 2, and 4 % betanin in fodder throughout the experiment. After 20 days of treatment, the fish were intraperitoneally injected with 20 % (v/v in peanut oil) CCl₄ at a volume of 0.5 mL/kg body weight. The fish were killed 3 days after CCl₄ intoxication, and then, histological and biochemical assays were performed. Results showed that CCl₄-induced liver CYP2E1 activity, oxidative stress, and injury, as indicated by the depleted glycogen storage, increased serum aspartate aminotransferase (AST)/alanine aminotransferase (ALT) activities and liver histological damage. Compared with the CCl₄ control group, the betanin-treated groups exhibited reduced CYP2E1 activity, decreased malondialdehyde level, increased liver antioxidative capacity (increased glutathione level and superoxide dismutase and catalase activities), increased liver glycogen storage, and reduced serum AST/ALT activities, with significant differences in the 2 and 4 % groups (p < 0.05). Histological assay further confirmed the protective effect of betanin. In conclusion, betanin attenuates CCl₄-induced liver damage in common carp. Moreover, the inhibition of CYP2E1 activity and oxidative stress may have significant roles in the protective effect of betanin.     

Immunomodulatory effect of cimetidine in common carp (Cyprinus carpio L.)

The main indication of cimetidine is being H₂-receptor antagonist, but studies suggest that cimetidine may also act as a non-specific stimulant of cell-mediated immunity and immunomodulator. In order to determine the immunomodulatory effect of dietary intake of cimetidine in the common carp (100 ± 10 g), subjects were fed diets containing 0 (control), 50, 100 and 200 mg cimetidine kg^?1 of dry diet for a period of 6 weeks. TLC and NBT assays were significantly (P < 0.05) stimulated in cimetidine-supplemented groups displaying the highest value in 200 mg kg^?1 group. A decrease (P < 0.05) in cortisol and ACH50 value was recorded in fish treated with cimetidine. Serum protein, albumin and serum globulin levels were not significantly changed. The findings of the present investigation suggest that the incorporation of cimetidine in the diet of common carp enhances the non-specific immunity.     

Effect of handling and fish size on secondary changes in carbohydrate metabolism in Atlantic salmon, Salmo salar L.

Two size groups (0.5 and 3 kg) of Atlantic salmon, Salmo salar L., were stressed by netting and transport from sea cages into land-based tanks. Handling lasted for 1 h. Before onset of stress, basal concentrations of haematocrit and haemoglobin, plasma cortisol and glucose, and liver and muscle glycogen were measured. All levels were within ranges reported for salmon. After handling and at chosen time intervals during recovery, samples were taken to judge the impact of handling and whether secondary changes in carbohydrate metabolism were related of fish size. A low cortisol peak indicated a mild stress reaction after handling independent to fish size. Plasma glucose peaked as cortisol declined, and returned to basal levels within 48 h. Liver glycogen seemed to be the main source of plasma glucose. No changes were measured in muscle glycogen concentrations. The results indicate a high tolerance to handling stress in Atlantic salmon independent of fish size.     

Physiological responses of juvenile wedge sole Dicologoglossa cuneata (Moreau) to high stocking density

Physiological responses to a high stocking density were tested in juvenile wedge sole Dicologoglossa cuneata (Moreau). Fish were kept at low (1 kg m⁻²), medium (3 kg m⁻²) and high (9 kg m⁻²) stocking densities for 22 days. No differences in the weight, length, survival and hepatosomatic index were observed among treatments. Basal plasma cortisol and osmolality were found to be directly and positively related to stocking density. A mild increase in plasma glucose was seen at medium density, and plasma protein was elevated at medium and high densities. The liver glucose and glycogen content was inversely related to stocking density. The liver triglyceride level was significantly elevated at the highest density, and the α-amino acid content decreased at the highest density. In muscle, glucose levels were significantly higher in fish kept at the lowest density; the α-amino acid content was elevated in fish kept at high density. In conclusion, plasma cortisol levels indicated an increasing stress level depending on the culture density, but significant changes in energy reserves did not occur in tissue (mainly liver and muscle glycogen and glucose reserves were significantly affected).