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1.
In this study, the effects of oral administration of different levels of Dunaliella salina (a natural β-carotene source) on growth parameters, immunological and hematological indices, as well as skin carotenoids, of Heros severus were investigated. One hundred and eighty H. severus weighing 27 ± 0.5 g were divided randomly into four groups in triplicate (15 fish in each replicate). Groups 1–4 received food supplemented with 0, 50, 100 and 200 mg kg?1 D. salina powder, respectively. After 6 weeks, the growth parameters were compared among the groups. Blood samples were taken from each group, and hematological parameters including red blood cell count (RBC), white blood cell count (WBC), hematocrit (PCV), hemoglobin (Hb) and immunological indices (serum and mucus lysozyme and bactericidal activity, resistance against Aeromonas hydrophila infection) as well as carotenoid content of skin were evaluated. Results showed that some growth indices increased significantly in fish fed with 100 and 200 mg kg?1 D. salina-supplemented food (P < 0.05). Although serum lysozyme activity was increased in fish fed with food supplemented with 100 and 200 mg kg?1 D. salina (P < 0.05), no significant change was observed in serum and mucus bactericidal activity and mucus lysozyme activity among the groups (P > 0.05). Most of the hematological parameters such as WBC, RBC, PCV and Hb significantly increased in D. salina-treated fish compared with controls (P < 0.05). Mortality induced after challenge with A. hydrophila in 200 mg kg?1 D. salina-treated fish was 36.67 %, which significantly decreased compared with control (P < 0.05). Skin carotenoid content in all D. salina treatments was statistically higher than that of control (P < 0.05). Conclusively, D. salina as a food additive can affect positively the growth, immunological and hematological parameters of H. severus.  相似文献   

2.
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.  相似文献   

3.
The effects of dietary selenium (Se) and vitamin E and their interaction in the nutrition of yellowtail kingfish, Seriola lalandi, were investigated. Six dietary treatments were prepared in a 3 × 2 factorial arrangement (not supplemented or supplemented with Se at 1 or 2 mg kg?1 × supplemented with vitamin E at 40 or 180 mg kg?1). A group of fish in triplicate were fed one of the six experimental diets for 6 weeks, and their growth performance, haematological and immune responses were measured. The results revealed positively interactive effects between dietary Se and vitamin E in yellowtail kingfish. Se significantly increased weight gain of fish fed diets low in vitamin E, but not high in vitamin E. Simultaneous supplementation of both micronutrients resulted in significant increase in serum bactericidal activity. There was no significant effect of Se or vitamin E on survival, feed intake, feed conversion ratio, haematocrit, white blood cell counts and fillet proximate composition. However, Se and vitamin E contents in fillets were significantly responsive to dietary Se and vitamin E, respectively. The supplemental level of Se at 2 mg kg?1 significantly increased red blood cell counts and haemoglobin concentrations, while lysozyme activity in skin mucus was significantly stimulated by vitamin E. The findings of Se and vitamin E supplementation in this study can be applied to improve growth and health indices of yellowtail kingfish.  相似文献   

4.
The present study was conducted to investigate the effects of astaxanthin on growth performance, biochemical parameters, ROS production, and immune-related gene expressions of the pufferfish (Takifugu obscurus) under high temperature stress. The experimental basal diets supplemented with astaxanthin at the rates of 0 (control), 20, 40, 80, 160, and 320 mg kg?1 were fed to fish for 8 weeks. The results showed that the fish fed diet with 80, 160, and 320 mg kg?1 astaxanthin significantly improved weight gain and specific growth rate. Furthermore, fish fed the moderate dietary astaxanthin increased plasma alkaline phosphatase activities, and decrease plasma aspartate aminotransferase and alanine aminotransferase activities. After the feeding trial, the fish were exposed to high temperature stress for 48 h. The results shown that astaxanthin could suppress ROS production induced by high temperature stress. Meanwhile, compared with the control group, the astaxanthin groups increased SOD, CAT, and HSP70 mRNA levels under high temperature stress. These results showed that the basal diet supplemented with 80–320 mg kg?1 astaxanthin could enhance growth, nonspecific immune responses, and antioxidant defense system and improve resistance against high temperature stress in pufferfish.  相似文献   

5.
Six oxidized fish oil contained diets were formulated to investigate the effect of graded levels of vitamin E (VE) (α-tocopherol acetate: 160, 280, and 400 mg kg?1) associated with either 1.2 or 1.8 mg kg?1 selenium (Se) on growth, body composition, and antioxidant defense mechanism of juvenile largemouth bass. Another control diet containing fresh fish oil with 160 mg kg?1 VE and 1.2 mg kg?1 Se was also prepared. Over a 12-week feeding trial, about 5 % of Micropterus salmoide fed diet OxSe1.2/VE160 showed inflammation and hemorrhage symptoms at the base of dorsal, pectoral, and tail fin. Fish in all treatments survived well (above 90 %). Feed intakes (88.42?89.58 g fish?1) of all treatments were comparable. Growth performances (weight gain and specific growth rate) and feed utilization (feed and protein efficiency ratio) were significantly impaired by dietary oil oxidation, and they did not benefit from neither VE nor Se supplementation. Regardless of dietary VE and Se supplementation, oxidized oil ingestion resulted in markedly decreased hepatosomatic index and intraperitoneal fat ratio. Oxidized oil ingestion also induced markedly lower liver and muscle lipid contents, and these effects could be alleviated by dietary Se supplementation. Dietary oil oxidation stimulated hepatic catalase activities relative to the control, and supplementation of VE abrogated this effect. Hepatic reduced glutathione content in the control was markedly higher than that of treatment OxSe1.2/VE160, without any significant differences comparing with the other oxidized oil receiving groups. Hepatic glutathione peroxidase activity and liver Se concentration reflected dietary Se profile, whereas liver VE level reflected dietary VE profile. Compared with the control, fish fed diet OxSe1.2/VE160 obtained markedly higher serum, liver and muscle malondialdehyde contents, which droppe significantly with increasing either VE or Se supplementation. In conclusion, the overall results in this study suggested that both VE and Se inclusion could protect largemouth bass from the oxidative damage challenged by dietary oil oxidation.  相似文献   

6.
Nucleotides (NT) are widely used as an immunostimulant in aquaculture. A 10-week feeding trial was conducted to evaluate the effects of dietary NT on the growth performance, immune response, disease resistance and intestinal morphology of the Pacific white shrimp Litopenaeus vannamei (initial mean body weight: 0.39 ± 0.00 g). Five isolipidic (about 7 % crude lipid) and isonitrogenous (about 39 % crude protein) practical diets were supplemented with graded levels of NT (0, 60, 90, 120 and 1200 mg kg?1), respectively. These diets were named as N1, N2, N3, N4 and N5. Each diet was randomly fed to six tanks of shrimps, and each tank contained 40 shrimps. The shrimps were fed four times daily (07:00, 11:00, 16:00 and 21:00 h). The results showed that there were no significant differences in survival, final weight, specific growth rate, feed intake, feed conversion ratio and whole-body compositions among all the treatments (P > 0.05). Shrimps fed the control diet had the significantly lowest activities of superoxide dismutase, total nitric oxide synthase and lysozyme (P < 0.05). However, those parameters increased when dietary NT increased from 60 to 120 mg kg?1 and decreased as inclusion level increased to 1200 mg kg?1 (P < 0.05). The cumulative mortality of the shrimps challenged with Vibrio parahaemolyticus was significantly higher in the treatments without dietary NT supplementation than those in treatments with dietary NT (≥90 mg kg?1) (P < 0.05). The jejunum wall thickness in shrimps fed the control diet was significantly lower than that in the treatments of N2, N3 and N4 (P < 0.05). For the villus height, the highest value (49.29 µm) was found in N3. In summary, the present study showed that 90 mg kg?1 of dietary NT is the optimum dietary level for good gut health, immune response and disease resistance of Pacific white shrimp fed a diet with 18 % fish meal.  相似文献   

7.
This study evaluated the effect of graded levels of dietary ascorbic acid (AA) (12.47, 20.27, 115.44, 475.50, 737.72, and 850.70 mg kg?1) on growth, hematology, intestinal morphometry, and phagocyte activity of hybrid sorubim Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans. Fish (n = 420, 14.57 ± 2.71 g, 15.11 ± 0.90 cm) were distributed in 30 polyethylene tanks (80 l) (5 replicates per treatment with 14 fish per tank) and fed for 45 days. Dietary treatment did not have a significant effect on growth metrics (P > 0.05). Fish fed 737.72 mg AA kg?1 had a higher villi height (289.80 ± 19.96 μm) (P < 0.05) than fish fed 850.70 mg AA kg?1 (245.4 ± 18.25 μm). Hemoglobin in fish fed 850.70 mg AA kg?1 (5.34 ± 0.96 g dl?1) was higher (P < 0.05) than fish fed 12.47 mg AA kg?1 (3.42 ± 0.55 g dl?1) and 20.27 mg AA kg?1 (3.06 ± 1.26 g dl?1). The erythrocyte number of hybrid sorubim fed 115.40 mg AA kg?1 (1.73 ± 0.27 × 106 μl?1) and 475.50 mg AA kg?1 (1.70 ± 0.28 × 106 μl?1) were higher (P < 0.05) than in those fed diets containing 20.27 mg AA kg?1 (1.11 ± 0.34 × 106 μl?1). There was no significant effect (P > 0.05) of dietary AA on leukocyte and thrombocyte and on phagocyte activity and phagocyte index. Inclusion of AA in feed seems to increase the integrity of the intestinal mucosa and stimulate erythropoiesis in hybrid sorubim catfish.  相似文献   

8.
The effect of supplemented commercial diets with diethylstilbestrol (DES—15, 30 and 60 mg kg?1) and 17 β-estradiol (E2—30 and 60 mg kg?1), two chemicals commonly used in sex reversal procedure in fish, on survival and growth parameters of juvenile European catfish (Silurus glanis) was evaluated. During the two experiments, lasting 28 days each, fish were kept at temperature 25.2–26.5 °C, pH 7.4–9.3 and oxygen concentration 5.0–7.3 mg O2 dm?3. DES supplementation resulted in depressed growth rate of catfish. In experimental groups fed with E2, no negative effect on growth parameters was found. Both chemicals did not result in observed mortality. In all of the experimental DES groups, hepatosomatic index increased significantly, which suggests negative influence on physiological condition of catfish. DES supplementation significantly changed cytological factors of liver cells and caused hepatic alterations in parenchyma, such as vacuolization and blood congestion. Similarly, supplementation of E2 in food resulted in changes in cytological parameters of hepatocytes. However, E2 did not cause pathological changes within the liver tissue. Histological examination of the catfish gonads showed 19 and 38 % of sterile fish after treatment with 30 and 60 mg kg?1 of DES, respectively. The results suggest that DES served in food could be ineffective in hormonal feminization process of European catfish. No disturbances of sex differentiation process after E2 treatment were observed. However, slight feminization effect in the highest level of E2 treatment group was recorded.  相似文献   

9.
Lipid peroxidation, protein oxidation and antioxidant activities of muscle, intestine, hepatopancreas and serum in juvenile Jian carp (Cyprinus carpio var. Jian) were investigated after feeding graded levels of biotin (0.010, 0.028, 0.054, 0.151, 0.330, 1.540 and 2.680 mg kg?1 diet) for 63 days. Both malondialdehyde and protein carbonyl content in all studied tissues and serum were the lowest in fish fed diets containing 0.151–0.330 mg biotin kg?1 diet and then increased in fish fed the diet with 2.680 mg biotin kg?1 diet (P < 0.05). Similarly, glutamate–oxaloacetate transaminase and glutamate–pyruvate transaminase activities in serum significantly decreased with biotin levels up to 0.151 mg kg?1 diet (P < 0.05). Conversely, capacities of anti-hydroxyl radical (AHR) and anti-superoxide anion (ASA) in the detected tissues and serum significantly improved with biotin levels up to 0.054–1.540 mg kg?1 diet and then decreased in 2.680 mg biotin kg?1 diet group for muscle and intestinal AHR as well as hepatopancreas ASA (P < 0.05). Activities of superoxide dismutase in all studied tissues and serum significantly elevated with biotin levels up to 0.330 mg kg?1 diet and then decreased when fish fed the diet with 2.680 mg biotin kg?1 diet, except intestine (P < 0.05). Meanwhile, activities of catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase and total thiol content in all studied tissues and serum showed the upward trend with biotin supplementations (P < 0.05). These results indicated that biotin improved antioxidant status and depressed lipid peroxidation and protein oxidation in all studied tissues and serum.  相似文献   

10.
This study shows the effects of dietary activated charcoal (AC) on health status, intestinal morphology and fillet geosmin content of Nile tilapia prior to harvesting (2 and 4 weeks). Four dietary treatments (each diet in six replicates) were formulated to incorporate AC at levels of 0, 10, 20 and 30 g kg?1 of the dry diet. Fish were reared in hapas, which were located in earthen ponds. There were not significant differences in growth performances among experimental treatments. The moisture and protein content in the fillet decreased and increased, respectively, as the incorporation level of AC increased. The hematological indices and several immune parameters did not differ significantly among treatment groups. Among the fifteen blood chemicals parameters examined, the significant reductions in protein and cholesterol and the changes in blood minerals were observed in fish fed dietary AC ≥20 g kg?1. Dietary AC tended to increase the height of intestinal villi and goblet cell number. Dietary AC also influenced the reduction in geosmin in the fish fillet. Taken together, these findings indicate that AC (at 10 g kg?1 diet) could be used as feed supplement for Nile tilapia prior harvesting to reduce geosmin without negative effects.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
The effect of graded levels of dietary available phosphorus (AP) on large Nile tilapia (145.87 ± 9.51 g) performance, feed efficiency, body composition and mineral retention in vertebrae was evaluated. All male fish were distributed into three replicates in fiberglass aquaria (800 L each; 12 fish per tank) for 87 days and hand fed to pelletized diets three times a day until apparent satiation. Diets with approximately 302 g kg?1 of digestible protein and 15.2 kJ g?1 of digestible energy with graded levels of dibasic phosphate yield AP levels of 2.39, 4.17, 6.12 and 8.91 g kg?1. At the end of the trial, feed intake, hepatosomatic index, fillet yield, whole body moisture and crude protein of fish fed 2.39–8.91 g kg?1 of AP diets were not significantly different. The supplementation of 6.12 and 8.91 g kg?1 of AP resulted in significantly increased weight gain, whole body ash and calcium. Whole body crude lipids significantly decreased with increasing AP from 6.12 to 8.91 g kg?1. However, concentration of zinc in the vertebrae was not affected by dietary treatments. The magnesium contents of the fish vertebrae were lower in fish fed lower dietary AP level. No effects of the dietary AP on apparent digestibility coefficients of energy and nutrients were observed. The study indicated that the dietary AP level of at least 6.12 g kg?1 satisfies the needs for growth performance, body composition and bone mineralization of large Nile tilapia.  相似文献   

14.
In this study, loach (Paramisgurnus dabryanus) were fed artificial diets containing 0.31 (control), 0.39, 0.48, 0.50 and 0.62 mg kg?1 of selenium (Se) for 60 days, respectively. Liver histopathology, hepatocyte ultrastructure, blood indices, biochemical parameters of liver functions and oxidative stress in the Se-treated loach were then assayed. The results showed the following: histopathological and ultrastructural lesions in liver were only observed in loach fed the 0.62 mg Se kg?1 diet; Haemoglobin and total protein were significantly increased in the 0.50 mg Se kg?1 group; albumin and high-density lipoprotein were increased significantly in the 0.48–0.50 mg Se kg?1 groups. However, white blood cell count was significantly decreased in the 0.48 mg Se kg?1 group; alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were decreased in the 0.39–0.50 mg Se kg?1 groups. In liver tissue, the content of hydrogen peroxide was lower than that of controls in the 0.48–0.50 mg Se kg?1 groups, and the malondialdehyde level was lowest in the 0.48 mg Se kg?1 group. The activities of superoxide dismutase and glutathione peroxidase were significantly increased in the 0.50 mg Se kg?1 group; catalase and total antioxidant capacity were markedly increased in the 0.48–0.50 mg Se kg?1 group. These present results indicated that the dietary Se requirement for loach is 0.48–0.50 mg Se kg?1 diet.  相似文献   

15.
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.  相似文献   

16.
This study was conducted to investigate the effects of dietary chitosan on growth performance, hematological parameters, intestinal histology, stress resistance and body composition in the Caspian kutum (Rutilus frisii kutum, Kamenskii, 1901) fingerlings. Fish (1.7 ± 0.15 g) were fed diets containing chitosan at different levels (0, 0.25, 0.5, 1 and 2 g kg?1 diet) for a period of 60 days. Results showed that the feed conversion ratio significantly decreased in fish fed diet containing 1 g kg?1 of chitosan compared to the other groups (P < 0.05), but there were no significant differences between treatments in terms of specific growth rate and condition factor (P > 0.05). Leukocyte increased in fish fed diet containing 2 g kg?1 of chitosan compared to the other groups (P < 0.05). Lymphocytes, eosinophils and neutrophils did not significantly change among dietary treatments (P > 0.05). Also, the chitosan supplementation did not affect the whole-fish body composition (P > 0.05). Light microscopy demonstrated that the intestinal villus length increased in fish fed diet containing 1 g kg?1 of chitosan compared to control group (P < 0.05). While 11 and 13 ‰ salinity and 30 °C thermal stress had no effect, 1 g kg?1 of chitosan (P < 0.05) showed highest survival rate (70 %) in 34 °C thermal stress. The results showed that chitosan in the diet of the Caspian kutum fingerlings could improve feed conversion ratio, the nonspecific defense mechanisms and resistance to some of the environmental stresses.  相似文献   

17.
A 13-week feeding trial was conducted to determine the optimal dietary ascorbic acid (AA) requirement of juvenile spotted rose snapper (Lutjanus guttatus). Six experimental diets containing 0, 7, 19, 29, 62 and 250 mg AA equivalent kg?1 diet, supplied as l-ascorbyl-2-polyphosphate designated as VC0, VC7, VC19, VC29, VC62 and VC250, were fed ad libitum to triplicate groups of 20 juveniles [initial weight (IW) of 8 ± 1.85 g]. Nutrient deficiency resulting in fin erosion, dark skin, desquamation and erratic swimming was observed after 8 weeks in fish fed diets from 0 to 29 mg AA kg?1. Fish that were fed all diets showed gill, kidney and brain alterations. The degree of tissue change values indicates that increasing vitamin C (VC) levels reduces these alterations. Fish fed diets VC29, VC62 and VC 250 showed a significantly higher growth rate in comparison with those fed the diets VC0, VC7 and VC17 (P > 0.05). The dietary requirement of VC in L. guttatus was estimated to be 29 mg kg?1 of AA based on weight gain and specific growth rate, but more than 250 mg kg?1 of AA is required to eliminate clinical signs and histopathological lesions.  相似文献   

18.
A study was designed to investigate the possible positive prebiotic effects of mannan oligosaccharides (MOS) on growth and reduction of anxiety behaviors in zebrafish (Danio rerio). The experimental diets were supplemented with 0, 2, 4, 6, or 8 g MOS kg?1 and were fed to juvenile fish (0.47 ± 0.017 g) in triplicates for six weeks. Significant differences were found in the final body weight, body weight intake, percent body weight intake, and specific growth rate among treatments. The regression analyses showed that the optimum MOS level was 4–4.1 g MOS kg?1 diet. Fish fed 4 g MOS kg?1 feed showed higher survival than the other treatments. Also, using the novel tank test, fish fed with 4 g MOS kg?1 diet showed lower anxiety by swimming in the upper portion of the tank. The other behavior parameters remained unaffected by the prebiotic. The results indicated the beneficial effect of the prebiotic MOS on growth and partly on welfare of zebrafish juveniles.  相似文献   

19.
Effects of nano and macro iron oxide as dietary iron sources on the growth, hematological, and biochemical characteristics of African catfish, Clarias gariepinus, fingerlings have been studied. Conventional basal feed was supplemented with nFe2O3 and Fe2O3 as treatments T1 and T2 (each at 0.0, 0.2, 0.4, 0.8, 1.2, and 1.6 g/kg supplementation levels) and given to C. gariepinus fingerlings (initial average weight and length 5.01 ± 0.80 g and 7.0 ± 0.53 cm respectively) for 7 weeks. After 7 weeks, the highest percent weight gains of 395.6% for T1 and 767.4% for T2 occurred simultaneously at the supplementation level of 0.4 g Fe kg?1 dry feed of both treatments, while the highest value for the control was 332.5%. Iron accumulations in liver were 2.727, 1.443, and 1.225 ppm, and red blood cell counts were 2.3, 6.0, and 7.0 x 1012/l for the same treatments. Supplementation of iron oxide in both nano and macro forms significantly improved the growth and health indices of C. gariepinus up to a concentration of 0.4 g Fe kg?1 dry feed. Also macro iron oxide was more effective than the nano form in enhancing fish growth within the supplementation levels (0.2?1.6 g kg?1) considered.  相似文献   

20.
Stress has a considerable impact on welfare and productivity of fish, and blood glucose level of fish may be a factor modulating stress response. This study evaluated the effect of blood glucose level and handling on acute stress response of grass carp Ctenopharyngodon idella. Fish were intraperitoneally injected with glucose at 0, 0.2, 0.5, and 1.0 mg g?1 body mass (BM) and then were exposed to handling for 5 min. Glucose injection resulted in increase of plasma glucose level and liver glycogen content and decrease of plasma lactate level. Handling resulted in increase of plasma levels of cortisol, glucose, and lactate and plasma lactic dehydrogenase (LDH) activity and decrease of liver glycogen content. At 1 h post-stress, the plasma cortisol level was lower in the stressed fish injected with glucose at 0.5 mg g?1 BM than the stressed fish injected with glucose at 0, 0.2, and 1.0 mg g?1 BM. No significant differences were found in the activities of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate kinase (PK) in the liver between the stressed and unstressed fish, regardless of the dose of glucose injection. At 1 h post-stress, the liver glucose-6-phosphatase (G6Pase) activity was higher in the fish without glucose injection than in the fish injected with glucose. This study reveals that blood glucose level can affect stress response of grass carp by modulating cortisol release and glucose homeostasis through glycogen metabolism and gluconeogenesis in the liver.  相似文献   

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