Effects of ferulic acid on growth performance,immunity and antioxidant status in genetically improved farmed tilapia (Oreochromis niloticus) fed oxidized fish oil

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia.     

Effect of oxidized fish oil on growth performance and oxidative stress of Litopenaeus vannamei

A 4‐week feeding trial was conducted to determine the effects of oxidized fish oil (OFO, POV: 234.84 meq kg^?1) on growth performance and oxidative stress of Litopenaeus vannamei. Five diets containing various OFO levels (0, 25, 50, 75 and 100 g kg^?1) with the same dietary lipid level were fed to L. vannamei. The results showed that the body weight gain and the specific growth rate of the shrimp fed with 50, 75 and 100 g kg^?1 of OFO diets decreased significantly (P < 0.05), whereas the hepatosomatic index increased significantly (P < 0.05). The malondialdehyde concentrations in the serum and muscle of the shrimp fed with 50, 75 and 100 g kg^?1 of OFO diets were significantly higher than that of the shrimp fed with fresh fish oil (P < 0.05). The total antioxidant competence decreased significantly compared with the control group. Therefore, dietary OFO affects the growth performance and increases the oxidative stress of shrimp.     

Effects of moderately oxidized dietary lipid and the role of vitamin E on the development of skeletal abnormalities in juvenile Atlantic halibut (Hippoglossus hippoglossus)

A study was conducted to characterize the effects of oxidized marine fish oil (MFO) on skeletal development in juvenile Atlantic halibut (Hippoglossus hippoglossus) and to determine the role of vitamin E on their bone health and antioxidant defense mechanisms. Juvenile halibut (4.5 ± 0.1 g) were fed six experimental diets containing untreated (peroxide value (POV)  =0.6 meq kg^− 1), mod`rately oxidized (POV = 7.5 meq kg^− 1) and highly oxidized (POV = 15 meq kg^− 1) MFO either with or without α-tocopherol acetate (0 or 300 IU kg^− 1) supplementation for 14 weeks. No significant effects on growth, survival, hepatosomatic indices, or hematocrit were observed among the dietary treatments. Fish fed diets without vitamin E and highly oxidized dietary lipids showed increased hepatic malonaldehyde concentrations indicating a response to oxidative stress. Both muscle and liver α-tocopherol concentrations were significantly lower in fish fed diets without vitamin E supplementation. Alkaline phosphatase levels in serum and bone were increased when vitamin E was present within the diet indicating higher bone formation activity by osteoblasts. Oxidized lipids and lack of dietary vitamin E significantly increased saturated and decreased polyunsaturated hepatic fatty acids. Liver lipids of fish fed diets without vitamin E also exhibited a lower ratio of 22:6n-3 to 22:5n-3 and n-3 fatty acids. The most frequent skeletal deformity observed was scoliosis, spanning the cephalic/prehemal regions, as well as the anterior hemal region of the vertebral column, which increased the frequency according to elevated levels of oxidized dietary lipid. Lordosis was also observed, with no specific pattern along the vertebral column. The pattern and type of abnormalities observed were similar to those reported in an earlier study in halibut from a commercial hatchery.     

Effects of fish oil with difference oxidation degree on growth performance and expression abundance of antioxidant and fat metabolism genes in orange spotted grouper,Epinephelus coioides

The present study was designed to assess the effects of fish oil with different oxidation degree on growth performance, serum biochemistry parameters and expressive abundance of oxidative stress and fat metabolism genes of orange spotted grouper Epinephelus coioides. The oxidized fish oil was conducted as follows: storage temperature: 4°C, ambient temperature (AT, [31.5 ± 3.5]°C); storage time: 45, 90, 135 days; antioxidant contents: 30 mg/kg (ethoxyquin [EQ]), 300 mg/kg Higher EQ (HEQ). According to the different treated conditions, 14 kinds of fish oil with different oxidation degree were obtained: T_F+EQ [positive control (fresh oil + EQ)], T_F (negative control [fresh oil]), T_4°C+45d+EQ, T_4°C+45d+HEQ, T_4°C+90d+EQ, T_4°C+90d+HEQ, T_4°C+135d+EQ, T_{4°C+135d+HEQ}, T_AT+45d+EQ, T_AT+45d+HEQ, T_AT+90d+EQ, T_AT+90d+HEQ, T_AT+135d+EQ, T_AT+135d+HEQ. Groupers were fed isonitrogenous and isolipidic diets containing 14 kinds of fish oil for 8 weeks, respectively. The results showed that survival, weight gain rate and thermal growth coefficient decreased as oxidation degree of dietary fish oil increased (p < 0.05). Higher serum total protein, triglyceride and glucose were observed with ascending oxidation degree of fish oil (p < 0.05). The genes expression levels of catalase, superoxide dismutase and glutathione peroxidase were up‐regulated with dietary oxidized level increasing (p < 0.05). In addition, the similar status also appeared in expression of peroxisome proliferator‐activated receptor gamma (PPARγ), hormone‐sensitive lipase (HSL) and fatty acid synthase (FAS) genes. In conclusion, the fish oil would show negative influence on the fish health until peroxide value and p‐anisidine value in oil exceed 12.96 meq/kg and 20.89. The best storage condition for fish oil is 4°C, 45 days and 30 mg/kg EQ which could keep fish oil available property to grouper.     

Effects of oxidized fish oil intake on tissue lipid metabolism and fatty acid composition of channel catfish (Ictalurus punctatus)

Recent studies in terrestrial animals have shown that feeding the oxidized lipids led to a reduction in triacylglycerols (TAG) and total cholesterol (TC) in liver and plasma. However, limited information is available on the effect of oxidized lipids on lipid metabolism in fish. In this study, four diets containing 0 g kg^?1 (control: fresh fish oil), 30 g kg^?1 (low‐oxidized oil, LOO), 60 g kg^?1 (medium‐oxidized oil, MOO) and 90 g kg^?1 (high‐oxidized oil, HOO) graded oxidized oil levels with the same dietary lipid level were fed to channel catfish for 86 days. The tissue lipid metabolism and fatty acid composition of the fish were investigated after this period. The results showed that plasma and liver concentrations of TAG and TC decreased with increasing dietary oxidized oil level (P < 0.05). Decreasing liver lipoprotein lipase and hepatic lipase activities were observed with increasing dietary oxidized fish oil inclusion (P < 0.05). The liver C22:6n?3 concentrations significantly decreased with increasing dietary oxidized oil level (P < 0.05), while muscle lipid had a high proportion of polyunsaturated fatty acids. It suggests that the adverse effects of dietary oxidized oil may be induced by inhibiting lipid metabolism enzymes and, consequently, inhibition of cholesterol homoeostasis and fatty acid synthesis.     

Effects of palm oil blended with oxidized fish oil on growth performances, hematology, and several immune parameters in juvenile Japanese sea bass, Lateolabrax japonicas

A 60-day feeding trial was conducted to determine the effects of palm oil blended with oxidized and non-oxidized fish oil on growth performances, hematology, and non-specific immune response in juvenile Japanese sea bass, Lateolabrax japonicas. Japanese sea bass (1.73 ± 0.01 g) were fed seven experimental diets containing 100 g/kg of dietary lipid in forms of palm oil (10P), fish oil (10F), fish oil blended with palm oil at different ratios, 6:4 (6F4P) and 4:6 (4F6P), oxidized fish oil (10OF), and oxidized fish oil blended with palm oil at different ratios, 6:4 (6OF4P) and 4:6 (4OF6P). After the feeding trial, the following results were illustrated. No significant effects were observed in survival, feed conversion ratio, condition factor, and hematocrit after feeding with experimental diets for 60 days. The relatively higher specific growth rate and hematology were observed in 6F4P. Furthermore, both palm oil and oxidized fish oil acted as a negatively on serum lysozyme activity (P < 0.05). This study suggested that a ration of 6F4P is recommended as an innocuous ratio for Japanese sea bass. Furthermore, according to the present investigation, palm oil seems to have the ability to improve the protein efficiency when added to oxidized fish diets as well as a positive trend to the growth performance (P > 0.05).     

氧化油脂对奥尼罗非鱼生长和抗氧化性能的影响

通过饲喂不同过氧化值油脂的饲料,研究奥尼罗非鱼(Oreochromisniloticus×O·aureus)的生长性能、肝胰腺抗氧化能力与氧化油脂的关系。试验结果表明:添加氧化油脂导致罗非鱼的增重率和饲料转化率显著下降(P<0·05),肝体比显著增加,但肝脂率、肌脂率的变化不明显(P>0·05);相对于过氧化值较低的饲料,饲料过氧化值(POV)为73·44mmol/kg时,肝胰腺中还原型谷胱甘肽(GSH)含量、超氧化物歧化酶(SOD)活力明显增高(P<0·05);氧化油脂对肝胰腺中丙二醛(MDA)含量无明显影响(P>0·05)。     

Effects of dietary fish oil replacement by various vegetable oils on growth performance,body composition and fatty acid profile of juvenile Malaysian mahseer,Tor tambroides

The current study was carried out to investigate the effects of replacing dietary fish oil with different vegetable oil sources and ratios on the growth performance and tissue fatty acid profiles of juvenile Tor tambroides. Three different vegetable oils (sunflower oil, linseed oil and palm oil) were used in two different substitution ratios (50% and 100%). A diet without replacement (100% fish oil) was used as a control. Triplicate groups of T. tambroides juveniles (5.0 ± 0.4 g) were fed the test diets for 9 weeks. The highest weight gain was observed in fish fed palm oil diets that, of course, were reared in aquaria. There was a significant effect (P < 0.05) of the percentage of fish oil replacement on the liver weight after controlling for the effect of fish weight (P < 0.05). The viscera weight significantly increased (P < 0.05) in fish on vegetable oil diets, and its highest amount observed among fish fed palm oil diets. Vegetable oil inclusion significantly reduced eicosapentaenoic acid and docosahexaenoic acid (DHA) concentrations in both muscle and liver of fish except for fish on 50% palm oil diet that had similar liver DHA content with those on control diet.     

Nutriphysiological and cytological responses of juvenile channel catfish (Ictalurus punctatus) to dietary oxidized fish oil

An 86‐day growth trial was conducted to investigate the effect of dietary oxidized fish oil on the growth and cytopathology of juvenile channel catfish (Ictalurus punctatus). Four diets containing 0 g kg^?1 (control: fresh fish oil), 30 g kg^?1 (low‐oxidized oil group), 60 g kg^?1 (medium‐oxidized oil group) and 90 g kg^?1 (high‐oxidized oil group) graded oxidized oil levels with the same dietary lipid level (90 g kg^?1 diet) were evaluated. The results show that the specific growth rate decreased with increasing dietary oxidized oil level (P < 0.05). All examined liver and kidney tissues in all dose groups exhibited what appeared as dose‐dependent cellular modifications. In addition, lipid droplet accumulation in the hepatocytes of fish in all dose groups was increased, and their localizations were distinctly different between all dose groups. The ultrastructural changes suggest the progression of mitochondrial vacuolation, especially in the renal tubules, in all dose groups. These results reveal a previously underappreciated effect of dietary oxidized fish oil on channel catfish kidneys. Overall, a series of nutriphysiological responses were adversely affected by exposure to dietary oxidized fish oil, and the corresponding interference patterns on the metabolism and transport of nutrients within cells were observed.     

Effects of different dietary lipid sources in the diet for Pangasius nasutus (Bleeker, 1863) juveniles on growth performance,feed efficiency,body indices and muscle and liver fatty acid compositions

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as the lipid sources, added at 120 g kg^?1 of crude lipid each. The diets were fed by hand to triplicate groups of Pangasius nasutus (Bleeker, 1863) juveniles (mean weight 10.66 ± 0.04 g), to apparent satiation twice daily for 12 weeks. Fish survival rate was 100% among all the treatments. Growth performance (DGR) was similar among fish fed the SBO, CPO and LO diets, but was significantly (P < 0.05) higher in the CPO compared to fish fed the control (FO) diet. Fish fed SBO and CPO diets also recorded significantly (P < 0.05) higher intraperitoneal fat compared to fish fed the control, whereas fish fed the LO diet did not significantly differ from the other treatments. Muscle and liver fatty acid profile of fish from all the treatments generally mirrored the composition of the diets fed and the major fatty acids recorded were 18:3n‐3 and 18:2n‐6 in the tissues of fish fed the LO and SBO treatments, respectively. Results of this study suggests that P. nasutus fed diets containing vegetable oils (especially CPO and SBO) produce better growth performance, without compromising fish survival and feed efficiency compared with those fed a diet containing only FO.     

Effect of oxidized fish oil and α‐tocopherol on growth,antioxidation status,serum immune enzyme activity and resistance to Aeromonas hydrophila challenge of Chinese mitten crab Eriocheir sinensis

The impact of dietary α‐tocopherol on juvenile Chinese mitten crab Eriocheir sinensis was experimentally evaluated in a 10‐week study. Crab were fed with nine diets including three levels of α‐tocopherol (0, 100 and 300 mg kg^?1 diet) and three levels of fish oil oxidation (fresh, moderate and high) in triplicates. Fresh and moderate oil oxidization enhanced weight gain, but moderate and high oil oxidization lowered survival and feed efficiency. The 100‐mg α‐tocopherol kg^?1 diet resulted in higher hepatopancreas MDA than other α‐tocopherol diets. High oil oxidization led to the lowest serum superoxide dismutase (SOD) and glutathione peroxidase (GPH‐PX). The serum SOD and GPH‐PX activities in crab fed 100 mg α‐tocopherol were higher than in those fed other α‐tocopherol diets. The diet without α‐tocopherol addition lowered lysozyme and phenoloxidase (PO) activities compared to other α‐tocopherol diets. Fresh fish oil diet increased PO activity compared to oxidized oils. High oil oxidization caused significantly more mortality than fresh or moderate oxidization after 7‐d postchallenge with Aeromonas hydrophila. Supplementation with α‐tocopherol significantly enhanced resistance to bacterial infection. This study indicates that α‐tocopherol can protect lipid from peroxidation and enhance disease resistance.     

Effect of different oil cake sources on growth, nutrient retention and digestibility, muscle nucleic acid content, gut enzyme activities and whole-body composition in silver barb, Puntius gonionotus fingerlings

Six iso‐nitrogenous (30% crude protein) and iso‐energetic (15 kJ g⁻¹) diets were prepared using different oil cake sources, viz. groundnut, soybean, sunflower, sesame, mustard and mixed oil cakes as major ingredients, and protein sources along with a minimum of 5% fish meal in each diet and were fed to silver barb Puntius gonionotus fingerlings (16.20±0.11 g) ad libitum four times a day close to an apparent satiation level for a period of 60 days to determine the effect of diets on growth, nutrient utilization, apparent digestibility coefficient (ADC) of the nutrients in the diets, gut enzyme activity, muscle nucleic acid content and whole‐body chemical composition of fish. Significantly higher (P<0.05) weight gain, specific growth rate, protein efficiency ratio, nutrient retention, ADC of nutrients in the diets, DNA:RNA ratio, protease and amylase activity with lower (P<0.05) feed:gain values were recorded in fish‐fed groundnut and soybean oil cake‐based diets than other diets tested. Among the dietary treatment groups, significantly higher (P<0.05) whole‐body protein, lipid and energy were also found in groundnut oil cake‐ and soybean oil cake‐based diets. The study suggests that the groundnut and soybean oil cake‐based diets, which led to significantly higher (P<0.05) growth and nutrient utilization than the other oil cake‐based diets in P. gonionotus fingerlings, may be used for pond culture of this species.     

Effects of different dietary lipids on growth,body composition and lipid metabolism‐related enzymes and genes in juvenile largemouth bass,Micropterus salmoides

This study investigates the effects of different lipids on growth, body composition and lipid metabolism of largemouth sea bass fish Micropterus salmoides. A total of 360 juvenile M. salmoides (mean ± SD mass = 33.83 ± 0.15 g) were randomly stocked into 12 tanks of 0.5 m³ volume for 8 weeks. Four replicates were made in each group, which were fed one of three diets containing fish oil (FO), soybean oil (SO) or lard oil (LO). The weight gain rate and specific growth rate did not differ among the groups (p > 0.05). Fish oil fish had the lowest condition factor (p < 0.05) and highest serum glucose content (p < 0.05). Crude lipid contents in the whole body and in the liver and muscle of FO fish were significantly lower than in the SO and LO groups (p < 0.05). The fatty acid composition of whole‐body lipids was closely correlated with that of the diet. The carnitine palmitoyltransferase 1 (cpt1) activity in the FO group was significantly higher than those in the SO and LO groups (p < 0.05). No significant differences in fatty acid synthase (fasn) activity were observed among the groups (p > 0.05). The Cpt1 and fasn gene expression levels in the FO group were significantly higher than those of the SO and LO groups (p < 0.05). The apolipoprotein B100 gene expression level was significantly higher in the SO group than in the FO group (p < 0.05). Fatty acid‐binding protein 1 gene expression levels in the FO and SO groups were not different (p > 0.05) but were both higher than that of the LO group (p < 0.05). The delta‐6 fatty acyl desaturase gene expression level in the LO group was significantly higher than that in the FO group (p < 0.05), but lower than that in the SO group (p < 0.05). It can be concluded that FO can be completely replaced by SO or LO in the M. salmoides diet, at least within the 8‐week culture period. Different types of dietary lipids significantly affect body condition and hepatic lipid metabolism in M. salmoides.     

Effects of dietary blend of fish oil with corn oil on growth and non-specific immune responses of grouper, Epinephelus malabaricus

A growth trial was conducted to investigate the effects of fish oil and corn oil on the growth and non‐specific immune responses of juvenile grouper, Epinephelus malabaricus. Five semi‐purified diets were supplemented with 40 g kg⁻¹ of either fish oil (F4), corn oil (C4) or blend of fish oil with corn oil at ratio of 3 : 1 (F3C1); 1 : 1 (F2C2) and 1 : 3 (F1C3). Each diet was fed to triplicate groups of grouper (mean initial weight: 10.26 ± 0.14 g) in a recirculating rearing system for 8 weeks. Weight gain and feed efficiency of fish fed the F4, F3C1 and F2C2 diets were the highest (P < 0.05), followed by fish fed the F1C3 diet, and the lowest in fish fed the C4 diet. Fish fed the C4 diet had a lower survival rate than fish on other dietary treatments. Fatty acid composition of liver and muscle in fish generally reflected the composition of the diet. Leukocyte superoxide anion (O⁻₂) production ratio was the highest in fish fed the F3C1 and F2C2 diets, followed by fish fed the F4 and F1C3 diets, and the lowest in fish fed the C4 diet. Fish fed the F3C1 and F2C2 diets had higher plasma lysozyme activities than fish fed the F4 and C4 diets. Plasma alternative complement activity was higher in fish fed the F3C1, F2C2 and F1C3 diets than fish fed the F4 and C4 diets. These results suggest that grouper fed diets with 3 : 1 or 1 : 1 of fish oil to corn oil ratio had similar growth to the fish fed diet with fish oil. Blend of fish oil with corn oil in diet significantly enhanced non‐specific immune responses of grouper when the fed diet contained fish oil as the only lipid source.     

The effect of dietary oxidized lipid levels on growth performance,antioxidant enzyme activities,intestinal lipid deposition and skeletogenesis in Senegalese sole (Solea senegalensis) larvae

Fish tissues, particularly rich in n‐3 PUFA, are prone to lipid peroxidation that can damage cellular membranes, cause severe lesions and subsequently incidences of disease and mortality. However, fish possess antioxidant defences, such as vitamin E (VE) and antioxidant enzymes, to protect them against oxidative damage. This study investigated the effects of an increasing gradient of oxidized dietary lipid on the survival, growth performance, skeletogenesis and antioxidant defensive processes occurring in Senegalese sole (Solea senegalensis) larvae. Four groups of fish were fed live prey enriched with experimental emulsions containing an increasing gradient of oxidized oil: non‐oxidized, NO+VE, 34.5 nmol MDA g^?1 w.w.; mildly oxidized, MO+VE, 43.1 nmol MDA g^?1 w.w.; highly oxidized, HO+VE, 63.3 nmol MDA g^?1 w.w. and highly oxidized without VE, HO‐VE, 78.8 nmol MDA g^?1 w.w. The oxidation levels increased in enriched rotifers following the oxidation gradient of the emulsions, but were not affected in enriched Artemia metanauplii. The oxidation status of Senegalese sole larvae increased during development, but this was not related to the dietary treatments. The increasing dietary oxidation levels did not affect the fatty acid profile, survival, growth performance and metamorphosis processes of sole larvae. Senegalese sole seem to activate antioxidant defence mechanisms in response to the increasing amounts of dietary peroxidized lipids, in a manner efficiently enough to prevent detection of any alterations of these physiological processes. Antioxidant systems and detoxification mechanisms appeared to occur through the consumption of dietary α‐tocopherol, the activation of the antioxidant enzymes (catalase, superoxide dismutase, glutathione S‐transferase, glutathione reductase) and the retention of oxidized fat in the intestinal enterocytes for detoxification prior to their utilization. However, fish fed the highest oxidized diet presented a reduction in bone mineralization, but lower incidence of deformities in the vertebral and caudal regions than fish fed the other diets. This study exemplifies the importance of rearing Senegalese sole larvae on non‐oxidized diets during the early larval development to avoid detrimental consequences in older fish, most notably in the process of skeletogenesis.     

Effects of different dietary lipid sources in the diet for Pangasius hypophthalmus (Sauvage, 1878) juvenile on growth performance,nutrient utilization,body indices and muscle and liver fatty acid composition

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as lipid sources each at inclusion level of 120 g kg^?1 and fed to triplicate groups of 15 juvenile iridescent shark, Pangasius hypophthalmus (Sauvage, 1878) (mean weight 10.00 ± 0.70 g) to apparent satiation twice daily for 12 weeks. The results showed that survival of fish was consistently over 95% for all treatments whereas growth performance in the SBO and CPO treatments was similar and significantly (P < 0.05) higher than for fish fed the LO diet. However, fish fed all vegetable oil‐based diets performed better than those fed the FO diet. Muscle and liver fatty acid composition for all treatments generally reflected the composition in the diet and the ratio of n‐3/n‐6 was found to play an important role in P. hypophthalmus, suggesting that excessive amounts of n‐3 fatty acids reduce the overall growth performance. Results of this study thus suggests that P. hypophthalmus fed diets containing vegetable oils (especially CPO and SBO) produce better growth than those fed FO diet without showing any signs of nutrient deficiency.     

Effects of dietary oxidized oil and vitamin E on the growth,blood parameters and body composition of juvenile Atlantic cod Gadus morhua (Linnaeus 1758)

The effects of oxidized dietary lipid and the role of vitamin E on the growth performance, blood parameters and body composition of juvenile Atlantic cod (Gadus morhua) were evaluated over a 9‐week feeding period. Four isonitrogenous experimental diets containing fresh or oxidized fish oil with or without added vitamin E (α‐tocopherol or mixed tocopherols) were fed to juvenile cod. The oxidized lipid used had a peroxide value of 94 mEq kg^?1 oil. No significant (P>0.05) differences in growth performance (weight gain and specific growth rate) or feed utilization (feed consumption and feed efficiency ratio) were observed when oxidized dietary lipid was used. The hepatosomatic index (HSI), viscerosomatic index (VSI) and haematocrit did not show any significant (P>0.05) differences among the treatments. However, erythrocyte osmotic fragility (EOF), referred to as susceptibility to haemolysis, of fish fed oxidized oil without added vitamin E was high in comparison with those fed unoxidized oil. Supplementation with α‐tocopherol appeared to decrease haemolysis, but mixed tocopherols had no significant (P>0.05) effect on EOF. The proximate composition of fish whole body was also affected by diet treatment. Fatty acid composition of liver total lipid reflected that of dietary lipid. Variations in tissue (liver and muscle) fatty acid composition among the treatments followed the same trend as those of the dietary fatty acids. Fish fed fresh oil had a higher proportion of polyunsaturated fatty acids (PUFA) in muscle and liver lipid than those fed oxidized oil. The results suggest that oxidized dietary oil affected juvenile Atlantic cod in certain tissues and that these effects could be alleviated by supplementation of sufficient amounts of vitamin E in the diet.     

Effects of dietary copper sources on growth,tissue copper accumulation and physiological responses of Japanese sea bass (Lateolabrax japonicus) (Cuvier, 1828) fed semipurified or practical diets

An 8‐week trial was conducted to compare the efficacy of a chelated copper (Cu) with the inorganic Cu (CuSO₄), in the diet of Japanese sea bass (Lateolabrax japonicus). Six diets were prepared based on two basal diets (semi‐purified or practical) at two Cu inclusion levels (0 and 4 mg kg^?1 from or chelated‐Cu), accordingly named as S0, SI4, SM4, P0, PI4 and PM4 respectively. Each diet was fed to quadruplicate groups of Japanese sea bass (initial weight: 65.0 ± 0.03 g) during the trial. Fish fed practical diets had higher feed intake, specific growth rate, protein efficiency rate (PER), liver Cu accumulation, liver Na⁺K⁺‐ATPase and plasma alkaline phosphatase, but lower hepatosomatic index than the groups fed semi‐purified diets (P < 0.05). Higher PER was exhibited by fish fed chelated‐Cu diets than that of fish fed CuSO₄ diets (P < 0.05). Although liver Cu accumulation was significantly higher in fish fed practical diets,, liver Cu content increased significantly with increasing dietary copper levels only in fish fed semipurified diets. Chelated‐Cu has higher efficiency than CuSO₄ when fed in practical diets. Poor growth performance of fish fed semipurified diets might induce underestimating the nutrient requirement of Japanese sea bass.     

Growth performance,oxidative stress indices and hepatic carbohydrate metabolic enzymes activities of juvenile Nile tilapia,Oreochromis niloticus L., in response to dietary starch to protein ratios

The effect of various dietary starch to proteins ratios (STA/P) on growth performance, oxidative status and liver enzyme activities involved in intermediary metabolism in juvenile Nile tilapia was evaluated. Four isocaloric‐practical diets (12.73 MJ kg^?1 digestible energy) with increasing STA/CP ratios were formulated. These were designated D₀ (344 g crude protein (CP) and 163.5 g starch (STA) kg^?1), D₁ (310 g CP and 243 g STA kg^?1), D₂ (258 g CP and 322 g STA kg^?1) and D₃ (214 g CP and 401 g STA kg^?1). Each diet was fed to triplicate groups of 60 fish (2.7 g) for 45 days. Compared with the control diet (D₀), significantly (P < 0.05) depressed growth and feed efficiency were observed only in the groups fed on diet D₃. The activities of hepatic enzymes involved in glycolysis and lipogenesis pathways were significantly enhanced in groups fed on diet D₃ compared with other diets. A significant (P < 0.05) increase in catalase activity was detected only in groups fed on diet D₃. Similarly, a significant (P < 0.05) enhancement in superoxyde dismutase, glutathione S‐transferases and glutathione peroxidise was observed in groups fed on diets D₂ and D₃ compared with other diets. Results demonstrate the ability of juvenile Nile tilapia to spare protein by dietary carbohydrate.     

饲料氧化鱼油引起草鱼肠道黏膜结构屏障损伤

为了研究饲料氧化鱼油对草鱼肠道屏障结构和肠道通透性的影响。(实验目的)以豆油、鱼油、氧化鱼油作为饲料脂肪源,分别设计鱼油组(6F)、豆油组(6S)、2%氧化鱼油(2OF)、4%氧化鱼油(4OF)及6%氧化鱼油(6OF)5组等氮、等能半纯化饲料,在池塘网箱养殖草鱼(平均体重74.8士1.2)72d。采用实时荧光定量PCR(qRT-PCR)的方法,测定了草鱼肠道紧密连接蛋白中闭锁蛋白Occludin,闭合蛋白Claudin3、Claudin15a和胞浆蛋白ZO-1、ZO-2、ZO-3的基因表达活性,并结合肠黏膜细胞间紧密连接结构透射电镜观察结果、肠道通透性标志性指标测定结果综合分析。(实验方法)结果显示：在添加氧化鱼油后,(1)血清二胺氧化酶活性、内毒素和D-乳酸含量都出现显著增加(P<0.05);(2)组成肠黏膜细胞间紧密连接结构的闭合蛋白Claudin-3、Claudin-15a和胞浆蛋白ZO-1、ZO-2、ZO-3基因表达活性显著下调(P<0.05),而闭锁蛋白Occludin基因表达活性出现不同程度的下调,但差异不显著(P>0.05);(3)透射电镜观察结果显示肠黏膜细胞间紧密连接结构出现缝隙;⑷饲料中的AV值、POV值、MDA含量与闭合蛋白Claudin-3、Claudin-15a,胞浆蛋白ZO-1、ZO-2、ZO-3和闭锁蛋白Occludin基因表达活性均显示负相关关系的变化趋势,其中饲料POV值、MDA含量与胞浆蛋白ZO-1基因表达活性呈极显著负相关关系(P<0.05)。(实验结果)结果表明,在饲料中添加氧化鱼油后,氧化鱼油中的过氧化物、丙二醛等油脂氧化产物导致组成肠道黏膜细胞间紧密连接结构的蛋白基因表达活性显著下调、紧密连接物理性结构显著损伤,致使肠黏膜屏障结构的完整性被破坏、肠黏膜通透性显著增加。(实验结论)