Clove oil attenuates stress responses in lambari,Astyanax altiparanae

The effects of clove oil anaesthetic on mitigating the physiological responses to air exposure, a stressful and routine situation in fish farming, laboratory conditions and sport fishing (catch and release), were evaluated in lambari (A. altiparanae). Adult females (n = 80) were randomly sorted to receive one of four treatments: control, anaesthesia (clove oil 50 mg/L), stress (5 min air exposure) and pre‐anaesthesia associated to stress. Their cortisol, glucose, lactate and haematocrit levels, the hepatosomatic index (HSI), liver and muscle glycogen, lipid peroxidation and the enzymatic activity of lactate dehydrogenase (LDH), catalase (CAT) and glutathione reductase (GR), were recorded. Glucose levels increased (53.9%) after anaesthesia and/or stress. The stress situation increased plasma cortisol (146.6%), lactate (294.6%) and lipid peroxidation in white muscle (45%) and decreased glycogen in white muscle (40.1%). The haematocrit increased after stress or anaesthesia (7.9%) while the liver glycogen and HSI did not change. Anaesthesia or stress did not affect the LDH but reduced the activity of CAT (46.1%) and GR (30.3%). We concluded that the anaesthetic clove oil in the concentration 50 mg/L modulates the physiological responses to air exposure stress improving the welfare; air exposure and clove oil affect the antioxidant defences of lambari; the activity of CAT and GR and the concentration of MDA can be used as biomarkers of stress in A. altiparanae.     

Can enzymatic antioxidant defences in liver discriminate between wild and sea cage-reared Bluefin Tuna quality?

Bluefin Tuna (Thunnus thynnus L.) is a fish species of high nutritional and commercial value that is increasingly farmed in the Mediterranean basin. Oxidative stress research in aquaculture is particularly important in the assessment of both the health of farmed fish and seafood quality. Reactive oxygen species (ROS) are able to start the lipid peroxidation process which is potentially dangerous in fish, since they contain a high percentage of n-3 polyunsaturated fatty acids, in particular C20:5 n-3 and C22:6 n-3, which account for most of seafood's nutritional quality. The study of the antioxidant system and how the various components interact to delay post-harvest lipid peroxidation covers both the improvement of quality and the extension of shelf life of the fresh tuna product.In this study, hepatic antioxidant enzymes (catalase—CAT, superoxide dismutase—SOD and glutathione peroxidase—GPx) and lipid peroxidation levels (TBARS) of wild and sea cage-reared tunas were investigated. The aim was to examine the possible oxidative stress state of wild tunas killed by different fishing methods, compared with reared specimens exposed to different periods of confinement but killed by the same method.No significant differences between wild specimens were found in relation to catching techniques. A significant depletion was observed in liver SOD activity in reared tunas (5.00 U/mg protein) in comparison with wild specimens (5.90 U/mg protein). No differences in liver CAT activity between wild and reared tunas were found. In reared specimens we observed an oxidative stress state indicated by an increase in GPx activity (104.70 U/mg protein and 0.83 U/mg protein in reared and wild tunas, respectively). A significantly higher liver lipid content was observed in reared tunas, but no significant differences between wild and reared tunas in terms of TBA reactive substances content were found (2.03 vs 2.02 micromol TBARS/mg lipid). Our results suggest that the increased GPx activity leads to the suppression of lipid peroxidation in liver of reared tunas. This is the first time that antioxidant enzyme activities have been assayed in Bluefin Tuna and the stress state seems to be related to the diet of reared specimens rather than to their confinement, as indicated by the absence of differences in the antioxidant activities related to the period of confinement.     

Oxidative stress parameters during starvation and refeeding periods in Adriatic sturgeon (Acipenser naccarii) and rainbow trout (Oncorhynchus mykiss)

This work analyses the changes in the redox balance in two fish species: Adriatic sturgeon ( Acipenser naccarii ) and rainbow trout ( Oncorhynchus mykiss ) during starvation and refeeding period. The starvation period raised the lipid peroxidation (thiobarbituric-acid-reacting substances) levels in liver and blood, while a decline occurred in the antioxidant enzymatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) in both fish species. In liver, after the refeeding period, SOD activity recovered in both species, whereas CAT activity recovered only in trout. Furthermore, in both tissues of the two species, the lipid peroxidation levels remained high after 2 months of refeeding. In white muscle and heart, the lipid peroxidation levels indicate that these tissues did not undergo oxidative stress during the 72-day period. During starvation, in the muscle of both fish the fall in the lipid peroxidation level coincided with a rise in CAT, GPX and GR. The refeeding period in this tissue raised the lipid peroxidation level, and the enzymatic activities reached the values of the first point of starvation. In heart, no oxidative damage was detected during starvation in either species. The CAT and SOD activities increased during the starvation period only in trout.     

Effect of taurine‐enriched diets on the Hsp expression,MAPK activation and the antioxidant defence of the European sea bass (Dicentrarchus labrax)

This study aimed to identify and characterize the cellular and metabolic response in vital organs of Dicentrarchus labrax, after feeding on soy‐based diets enriched with different taurine concentrations (T0.2, T0.5, T1.0 w/w). Molecular responses (expression of Hsp70, Hsp90, phosphorylation of p38 mitogen‐activated protein kinase‐p38MAPK and extracellular signal‐regulated kinases‐ERK1/2) were addressed. Metabolic and antioxidant capacities such as activities of citrate synthase (CS), malate and lactate dehydrogenase (MDH, L‐LDH), superoxide dismutase (SOD), catalase (CAT) and levels of thiobarbituric acid‐reactive substances (TBARS) were assessed. The most intense changes were detected in the liver and in the anterior intestine showing that taurine induces important protective biochemical mechanisms. Specifically, in the liver and the anterior intestine, Hsp and MAPK levels, as well as L‐LDH activity levels were up‐regulated under the effect of taurine diets. T diet had no major effect on the activity levels of CS, SOD and TBARS, except for MDH in the liver and catalase in the anterior intestine, where activity levels of these enzymes were increased under the effect of T0.2 and T1.0, respectively. These results may facilitate monitoring of adequate health status of farmed fish, exploiting the beneficial T effects and could assist at the formulation of aquaculture feeding strategies.     

Effect of dietary lipid oxidation with vitamin C and E supplementation on fillet quality of red sea bream,Pagrus major (Temminck & Schlegel) during storage

An experiment was conducted to determine the effects of different levels of dietary vitamin C (VC) and E (VE) supplementation on fillet quality of red sea bream fed oxidized fish oil (OFO). Fish with an average body weight of 205.0 g were fed four test diets for 9 weeks. Control diet contained fresh fish oil (FFO) with 100 mg kg^?1 of VE and 500 mg kg^?1 of VC (FFO100E/500C). The other three diets contained OFO with varying levels of VE (mg kg^?1) and VC (mg kg^?1) (OFO100E/500C, OFO200E/500C and OFO200E/1000C). After feeding trial, two fillets from each fish by hand filleting were stored in a refrigerator at 4°C for 96 h during analyses. Results showed that fish fed OFO increased fillet thiobarbituric acid reactive substances (TBARS) and K‐value, and decreased fillet VC and VE concentrations during storage time. Supplementation of VC did not have any detectable effect on fillet quality. Increasing dietary VE supplementation increased fillet VE concentrations, reduced fillet TBARS and K‐value values of red sea bream. Therefore, we suggest that dietary supplementation of 200 mg kg^?1 of vitamin E could improve fillet oxidative stability of red sea bream fed OFO.     

Biomarkers of oxidative stress and antioxidant defences as indicators of different disinfectants exposure in the heart of rainbow trout (Oncorhynchus Mykiss Walbaum)

The aim of this study was to evaluate the impacts of different disinfectants' treatment using in aquaculture on the oxidative stress biomarkers such as thiobarbituric acid reactive substrates (TBARS) and carbonyl derivatives of protein oxidative modification, as well as antioxidant defences [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx) activity] and total antioxidant capacity (TAC) in the heart tissue of rainbow trout (Oncorhynchus mykiss). In the disinfectants exposure, fish were treated to chloramine‐T (final concentration 10 g m^?3), chloride dioxide (5 g m^?3), formalin (200 mL m^?3) and CIP disinfectant based on peracetic acid and hydrogen peroxide (16 mL m^?3) for 20 min and repeated three times every 3 days. Both chlorine dioxide and formalin treatment was indicated by a significant increase in the level of heart TBARS levels and carbonyl derivatives content and decreased SOD activity. Tissue oxidative stress biomarkers were unchanged upon chloramine‐T or CIP disinfectant exposure. Increased oxidative stress could modify antioxidant defences, principally causing increased CAT activity in the heart tissue of formalin‐ or ClO₂^?‐exposed fish. The correlation between oxidative stress biomarkers and GPx activity indicates that enzymes related to glutathione metabolism were responsible to formalin or ClO₂^?‐induced oxidative stress. Hence, TBARS, carbonyl derivatives and antioxidant defences could be used as biomarkers in evaluating the toxicity of formalin and chlorine dioxide using as disinfectants to trout.     

Dietary bee pollen affects hepatic–intestinal histomorphometry of Nile tilapia fingerlings

The bee pollen is considered an excellent source of flavonoids, carotenoids, phenolic compounds, sterols and minerals; and possesses the ability to boost the immune system, antioxidant action and other interesting therapeutic effects. This study was carried out aiming to evaluate the inclusion of bee pollen in extruded commercial diets of Nile tilapia fingerlings and its effects on the hepatic‐intestinal histomorphometry and zootechnical performance. A total of 225 tilapia fingerlings (1.25 ± 0.05 g) were distributed in a completely randomized design in 15 tanks (30 L) maintained in a recirculation water system with three treatments (0% or control, 1.5% and 2.5% of bee pollen inclusion) and five replicates. Feeding rates were defined from the weekly biometrics and periodic monitoring of the physical–chemical water quality parameters. The water quality variables remained within the appropriate range for the species throughout the experiment. There was no significant difference for the somatic indexes and zootechnical parameters in this experiment. However, the inclusion of bee pollen in Nile tilapia fingerlings diets showed a linear increase in hepatocyte morphology (p = .0098). For the intestinal variables of villus height a significant linear increase was observed (p < .05) as the pollen inclusion increased. In fish that received 2.5%, the number of goblet cells was significantly higher (p < .001) than control group and 1.5%. In this sense, the inclusion up to 2.5% bee pollen in extruded commercial diets of Nile tilapia fingerlings had a positive impact on hepato‐intestinal histomorphometry without causing negative effects on the zootechnical performance.     

Effect of dietary taurine supplementation on growth,digestive enzyme,immunity and resistant to dry stress of rice field eel (Monopterus albus) fed low fish meal diets

This study was conducted to evaluate the effect of dietary taurine supplementation on growth, immunity and resistant to dry stress of rice field eel (Monopterus albus) fed low fish meal diets. Six isonitrogenous and isolipid diets (32% fish meal) supplemented with six taurine concentrations (0, 0.3, 0.6, 0.9, 1.2 and 1.5 g/kg; designated as T₀, T_0.03, T_0.06, T_0.09, T_0.12 and T_0.15 groups, respectively) were prepared. A diet including 42% fish meal (FM group) was also included as a reference. The results showed that specific growth rate (SGR) in FM group was significantly higher than that in lower fish meal treatments. SGR significantly increased and slowly decreased with the increase in taurine supplementation level. Lipase activity value in intestine of M. albus fed FM diet was maximum, and with the increase in taurine supplementation level, lipase activity significantly increased and slowly decreased. The FM group had relative higher total antioxidant capacity (T‐AOC) content, catalase (CAT), total superoxide dismutase (T‐SOD), and lyzozyme (LZM) activities in serum than the other groups. With the increase in dietary taurine supplementation level, the CAT, T‐SOD, T‐AOC and LZM activities in serum significantly increased and then decreased. In the dry stress experience, the adrenaline (AD), cortisol (COR), glucose (GLU), total cholesterol (CHOL), and malondialdehyde (MDA) concentrations, T‐AOC content, CAT and T‐SOD activities in serum of M. albus in the four groups first increased and reached the peak at 2 hr, and then decreased under air‐exposure stress. Compared to the FM group, T_0.15 group had relative higher T‐AOC content, CAT and T‐SOD activities, and lower AD, COR GLU, TC and MDA concentrations.     

The effects of the supplementation of activated charcoal on the growth,health status and fillet composition-odor of Nile tilapia (Oreochromis niloticus) before harvesting

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.     

Influence of dietary zinc on lipid peroxidation,protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to study the effects of dietary zinc on lipid peroxidation, protein oxidation and antioxidant defence of juvenile Jian carp (Cyprinus carpio var. Jian) by feeding fish with increasing levels of zinc (15.3, 26.9, 40.8, 58.2, 68.9 and 92.5 mg Zn kg^?1) for 6 weeks. Results indicated that malondialdehyde (MDA) content and protein carbonyls (PC) in serum were the highest in fish fed diet containing 15.3 mg zinc kg^?1 diet (P < 0.05). Serum antisuperoxide anion (ASA), superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), glutathione reductase (GR) activities and glutathione (GSH) content were improved with increasing dietary zinc levels up to 40.8 mg zinc kg^?1 diet (P < 0.05) and levelled off (P > 0.05). Serum antihydroxy radical (AHR), catalase (CAT) and glutathione‐S‐transferase (GST) activities followed the similar pattern to that observed in ASA. The MDA and PC levels, ASA, AHR, SOD, CAT, GPx, GR, GST activities and GSH content in intestine, hepatosomatic and muscle tissue followed the similar pattern to that observed in serum. The present results indicated that zinc decreased lipid peroxidation and protein oxidation and improved antioxidant defence in fish.     

Olive oil by-product as a natural antioxidant in gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>) nutrition

The aim of the study reported here was to evaluate the efficiency of a natural antioxidant substance in gilthead sea bream (Sparus aurata) feeds. An olive oil by-product, olive mill vegetation water (VW), contains polyphenols, which have a strong antioxidant activity. A 147-day growth trial was conducted (monofactorial balanced, 4 × 3) with diet as the experimental factor. Two diets [isonitrogenous (crude protein 40%) and isoenergetic (gross energy = 18MJ kg⁻¹ on a dry weight basis] were formulated with 1 and 5% of VW (VW1, VW5); the control diet did not contain VW. A total of 600 juvenile gilthead sea breams (mean body weight 114.1 ± 5.7 g) were utilised. Production parameters and somatic indexes were calculated at the end of the growth trial. Antioxidant activity in fish fillets was investigated using TBARS and DPPH assays. A number of haematological parameters and digestive enzyme patterns were measured in fish in the middle and at the end of the experiment. The TBARS values showed slight delays in the development of oxidation in the fillet of fish fed with VW. There was no statistical difference between fish fed with the experimental diet and the control group, except for maltase activity, which increased with increasing VW in the feed. We found that the use of VW in a gilthead sea bream diet did not have any detrimental effects on gilthead sea bream production and physiological parameters and slightly improved the conservation of the fish fillets.     

Effects of diludine supplementation on growth performance,liver antioxidant enzyme activities and muscular trace elements of rainbow trout (Oncorhynchus mykiss) juveniles at a low water temperature

Diludine is used as an effective agent reducing mutagenic effects of environmental pollutants, increasing productivity and protecting reproductive system of parental individuals and quality of their offspring. A 10‐week study was conducted to evaluate potential effects of diludine on rainbow trout (Oncorhynchus mykiss) juveniles growth performance, feed utilization, survival rate, liver antioxidant enzyme activities (superoxide dismutase, SOD, EC1.15.1.1 ; catalase, CAT, EC1.11.1.16 ; glutathione peroxidase, GPx, EC 1.11.1.9 ; glutathione reductase, GR, EC1.6.4.2 ; glucose‐6‐phosphate dehydrogenase, G6PD, EC1.1.1.49 and glutathione S‐transferase, GST, EC1.5.1.18 ), the levels of malondialdehyde (MDA) as a lipid peroxidation marker and muscular trace elements at a low water temperature (9 °C). Diludine was added at 0.2, 0.5 and 1 g kg^?1 to a fish meal–based control diet, and each diet was fed to triplicate groups of rainbow trout juveniles. After 10 weeks, there were no differences in survival rate between fish fed experimental diets (P > 0.05). It was observed that a significant improvability existed for both growth and feed utilization in fish fed diets supplemented with diludine (P < 0.05). Antioxidant enzymes showed significantly increased activity in liver tissues (P < 0.05) and then a decrease to initial activity levels during the experimental time. (GPx activity was not determined in the juvenile livers.) SOD and GST activities in liver of fish fed the diets with diludine tended to be higher and GR activity tended to be lower than that in fish fed the basal diet. However, in general, it was determined that different concentration of diludine did not affect the studied antioxidant enzyme activities except G6PD in the liver of juveniles fed the diet with 1 g kg^?1 diludine. On the other hand, the significant reduction was found in MDA levels in the fish fed the diets with diludine compared with basal diet on the 14th and 28th days of experiment. It was also observed that Cu, Fe, Mg, Zn and Se levels were significantly higher in the juveniles fed the diet with 1 g kg^?1 diludine than those fed the basal diet. In conclusion, the results of this trial indicate that 1 g kg^?1 dietary supplementation with diludine seems to be most positive for rainbow trout production in cold‐water adaptation.     

Curcumin analogue inhibits lipid peroxidation in a freshwater teleost, <Emphasis Type="Italic">Anabas testudineus</Emphasis> (Bloch)—an in vitro and in vivo study

The effect of a synthetic curcumin analogue (salicylcurcumin) on fish lipid peroxidation was investigated in both in vitro and in vivo conditions using a teleost model Anabas testudineus (Bloch). Curcumin analogue inhibited the formation of lipid peroxidation products and thiobarbituric acid reactive substances (TBARS) content at the three concentrations (10⁻² M, 10⁻³ M and 10⁻⁴ M) in vitro. TBARS content was reduced by 80% in the liver and 68% in brain by the higher concentration of salicylcurcumin. For in vivo study, salicylcurcumin (0.5%) was supplemented along with the basal feed for a period of 60 days. It produced a 60% reduction in liver TBARS content. The antioxidant enzyme superoxide dismutase (SOD) was stimulated, whereas catalase (CAT) and glutathione peroxidase (GPx) were inhibited. Glutathione (GSH) was reduced and glutathione reductase (GR) unchanged. Even though there was an increase in SOD activity, the CAT and GPx did not increase accordingly, maybe due to the direct scavenging of H₂O₂ by salicylcurcumin. The protein content also increased in the curcumin-fed animals, indicating a positive growth-promoting effect. Therefore, it would be beneficial to supplement salicylcurcumin along with the aquaculture feed in order to help the fish to cope with adverse conditions in the environment. This would increase the survival rate, disease resistance and ultimately the growth rate.     

Effects of dietary riboflavin levels on antioxidant defense of the juvenile grouper <Emphasis Type="Italic">Epinephelus coioides</Emphasis>

This study was conducted to evaluate the effects of dietary riboflavin on antioxidant defense in the juvenile grouper Epinephelus coioides. Graded levels of riboflavin (0.9, 1.6, 4.4, 6.7, 12.9 and 19.4 mg kg⁻¹ dry diet) were fed to grouper juveniles (mean weight: 14.90 ± 0.46 g) for 12 weeks. Higher levels of liver thiobarbituric acid reactive substances (TBARS) content were observed in grouper fed low doses (0.9 and 1.6 mg kg⁻¹ diet) of riboflavin. Both liver glutathione reductase (GR) activity and its activation coefficient (GR-AC) poorly responded to riboflavin deficiency. In addition, other indices of the glutathione-dependent defense system, including the activities of glutathione peroxidase (GSH-PX) and glutathione-S-transferase (GST), and the content of glutathione (GSH), were also non-significantly affected by dietary riboflavin levels. However, the activities of liver superoxide dismutase (SOD) and catalase (CAT) were significantly lower in fish fed 0.9 mg kg⁻¹ diet, with a positive correlation between the different groups. In conclusion, the present study indicated that the juvenile grouper fed the riboflavin-unsupplemented diet was susceptible to lipid peroxidation (LPO), with lower SOD and CAT activities in the liver. However, the glutathione-dependent defense system of grouper was not affected by dietary riboflavin levels.     

The protective role of ascorbic acid (vitamin C) against chlorpyrifos-induced oxidative stress in Oreochromis niloticus

Ability of ascorbic acid (vitamin C) to attenuate oxidative damage was evaluated in liver and brain tissues of Oreochromis niloticus (O. niloticus) experimentally exposed to sublethal concentrations of chlorpyrifos (CPF). O. niloticus was exposed to sublethal concentrations of CPF at 12?μg/L (CPF1) and 24?μg/L (CPF2) for 96?h. The fish of vitamin C (Vit C) and CPF2?+?Vit C groups were fed with Vit C supplemented diet (200?mg Vit C/100?g feed). A significant increase in thiobarbituric acid-reactive substances (TBARS) level (P?相似文献   

Effects of acute environmental and handling exposure on physiology and fillet quality of market‐sized Channel Catfish

Catfish Ictalurus spp. are subjected to stressful conditions during harvest, which may be linked to fillet coloration and quality. Poor water quality in ponds, socks or hauling tanks, as well as handling stress, have been suggested to cause red fillets in catfish; however, chronic exposure has not resulted in red fillets. Short‐term occurrences of extreme poor water quality, particularly low dissolved oxygen, high carbon dioxide and high temperature, may occur in ponds or during harvest. Therefore, market‐sized Channel Catfish Ictalurus punctatus were acutely exposed (12 hr) to one of the three water quality treatments while confined during a simulated socking procedure and evaluated for stress responses by means of change in blood parameters and fillet quality. In fish subjected to the extreme treatment, hematocrit, plasma cortisol, glucose and lactate levels increased, with 22% mortality, indicating highly stressful conditions. In fish subjected to moderate and typical (control) treatments, cortisol increased but a lack of change or decrease in glucose and lactate indicated minimal anaerobic metabolism. Only one red fillet was produced by the extreme treatment and two by the typical treatment; therefore, the results suggest red fillets are not a product of poor water quality compounded by handling during harvest.     

The potential for rice wine residual as an alternative protein source in a practical diet for Nile tilapia (Oreochromis niloticus) at the juvenile stage

This study investigated the utilization level of rice wine residual (RWS) in a diet for juvenile Nile tilapia. The effects of RWS in diets were evaluated for growth (at week 4), fillet composition, haematological and blood chemical parameters (at weeks 3 and 6) and intestinal morphology (at week 6). The dietary treatments (each diet in triplicate groups) consisted of seven isonitrogenous (320 g kg^?1 crude protein) servings that were formulated to include RWS at levels of 0 (control diet), 75, 150, 225, 300, 375 and 450 g kg^?1 dry diet (Diets 1–7, respectively) and a commercial diet (Diet 8). The growth performances of fish in the groups on Diets 1–4 did not differ significantly. There were no marked variations in fillet composition, serum lysozyme, haematological profiles and blood urea nitrogen (BUN) among treatment diets, except for haematocrit and BUN (week 3) and haemoglobin (week 6) of fish on Diets 6–7. While the blood glucose increased as the amount of RWS incorporation increased (P < 0.05), the cholesterol decreased (P < 0.05). Only intestinal morphometry of fish fed Diet 7 differed significantly from any of the other treatments. Taken together, RWS (at 225 g kg^?1 diet) has the potential for use in juvenile Nile tilapia diet without negative effects.     

Deposition of conjugated linoleic acid in market size sea bass (Dicentrarchus labrax) and its effects on performance,composition and fillet sensory and texture attributes

The effect conjugated linoleic acid (CLA) accumulation in fish fillet on sensory and texture attributes has been evaluated. Fish were fed diets with graded levels of CLA, which were administered for different durations prior to harvest. Fish were sampled for fillet proximate composition and fatty acid profile for sensory and texture parameters at the end of the trial. Growth performance, feed conversion ratio and muscle proximate composition were not affected by dietary treatments. Muscle fatty acid profile was not affected by dietary treatments despite the increase in saturated fatty acids in fish fed diet with 10 g kg⁻¹ of CLA for 16 weeks before harvest. Besides, the deposition levels of CLA isomers increased gradually depending on the CLA treatment, reaching its maximum level in fish fed 10 g kg⁻¹ CLA diet for 20 weeks before harvest. Fish fed 10 g kg⁻¹ were juicier (P < 0.05) compared with control group, whereas fish fed 5 g kg⁻¹ CLA diet were less (P < 0.05) chewy than fish fed control diet regarding sensory attributes. Texture parameters were not significantly affected by dietary CLA. These results suggest that market size European sea bass could successfully incorporate CLA isomers with some minor positive effects on sensory analyses.     

Effect of the Inclusion of Dried Tetraselmis suecica on Growth,Feed Utilization,and Fillet Composition of European Sea Bass Juveniles Fed Organic Diets

Dried Tetraselmis suecica was evaluated as a fish protein substitute when incorporated to replace (protein basis) 10% (TETRA10) and 20% (TETRA20) of the control diet. The diets were offered to nine groups of European sea bass (72 g) over 63 days. Test diets did not affect zootechnical performances nor carcass or fillet yields and proximate analysis of edible portion. Feeding TETRA20 resulted in lower apparent digestibility coefficients of protein, lipid, and organic matter, and hepatosomatic index compared to the control diet. T. suecica was able to replace up to 20% of fish protein without hampering growth performance and major quality traits of sea bass.     

Influence of dietary garlic (Allium sativum) on the antioxidative status of rainbow trout (Oncorhynchus mykiss)

Oxidative damage by free radicals has been implicated in the pathogenesis of several diseases. In this study, the antioxidative effect of dietary garlic on rainbow trout was examined. Trout fingerlings were fed on diets containing 10, 20, 30, 40 and 50 g garlic powder kg^?1 diet. Serum lipid peroxides and activities of antioxidant enzymes were measured. Serum thiobarbituric acid reactive substances (TBARS) assay showed that garlic consumption that resulted in a significant decrease in lipid peroxidation. The lowest levels of TBARS were observed in fish fed diet supplemented with 30 g kg^?1 garlic. However, higher doses of garlic (40 and 50 g kg^?1 diet) caused no further reduction in serum TBARS. The results showed a significant increase in superoxide dismutase in all of the garlic‐treated groups compared with the control. Ingestion of 10, 20 and 30 g kg^?1 dietary garlic resulted in a significant reduction in the catalase activity compared with all but the 10 g kg^?1 group. There was no significant difference in glutathione peroxidase activity among the different groups. Serum alanine aminotransferase and aspartate aminotransferase levels increased significantly in trout‐fed diets containing 40 and 50 g kg^?1 garlic powder. These results suggest that dietary garlic may improve the antioxidant status of rainbow trout. However, undesirable effects of higher doses of garlic should be considered.