Effects Of Ethoxyquin, Oxidized Fish Oil And Chromium Polynicotinate On The Growth Performance And Their (or Metabolites) Residues In Tissues Of Large Yellow Croaker Pseudosciaena Crocea And Japanese Seabass Lateolabrax Japonicus

Feeding trials were conducted to investigate the effects of Ethoxyquin(EQ), oxidized fish oil (with or without vitamin E supplementation) and chromium polynicotinate on the growth performance, body composition and metabolites residue in tissues of large yellow croaker(Pseudosciaena crocea) and Japanese seabass(Lateolabrax japonicus). The experiments were carried out in marine cages (1.0×1.0×1.5 m or 1.5×1.5×2.0 m) in Xiangshan Bay, Zhejiang province, South China. Results of the present studies are presented as follows:1. Five experimental diets were formulated to contain graded levels of EQ (0,50, 150,450 and1350 mg kg-1). Each diet was randomly fed to three sea cages (1.0×1.0×1.5 m), and each cage was stocked with 60 large yellow croaker (with an initial body weight of 7.82±0.68 g). The feeding trail last for 10 weeks. Survival of large yellow croaker was more than 93%, and irrespective of dietary EQ levels (P>0.05). Specific growth rate (SGR) decreased with the increase of dietary EQ. SGR of fish fed the diet with 1350 mg kg-1 EQ was significantly lower than the other treatments (P<0.05). There were no significant differences in SGR among fish fed diets with or less than 450 mg kg-1 EQ (P>0.05). No significant difference in feed intake (FI) was found among dietary treatments (P>0.05). Feed efficiency ratio (FER) first increased, and then decreased with increasing dietary EQ, but no significant differences were observed among dietary treatments(P>0.05). No significant differences were found in moisture, protein, and ash content among dietary treatments (P>0.05). The lipid content, however, in fish fed the diets with EQ was higher than those fed the diet without EQ. The content of eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) in the diets with EQ addition were higher than the control (0 mg kg-1), indicated that dietary EQ efficiently protect the highly unsaturated fatty acid (HUFA) from oxidizing. The hepatosomatic index (HIS) and condition factor (CF) generally decreased with increasing dietary EQ level. The CF in fish fed the diet containing 1350 mg kg-1 EQ was significantly lower than the others. The VSI of fish firstly decreased with the increase of dietary EQ, the lowest value was recorded in fish fed diet with 150 mg kg-1 EQ, then increased with increasing dietary EQ. Results of the present study showed that EQ level in the diet of large yellow croaker should not more than 50 mg kg-1.2. Five experimental diets were formulated to contain graded levels of EQ (0,50, 150,450 and1350 mg kg-1). Each diet was randomly fed to three sea cages (1.5×1.5×2.0 m), and each cage was stocked with 30 Japanese seabass (with an initial body weight of 8.01±0.76 g). The feeding trail last for 12 weeks. Survival of Japanese seabass was more than 78.9%, regardless of dietary EQ concentrations (P>0.05). Specific growth rate (SGR) was significantly influenced by dietary EQ level (P<0.05). Fish fed the diets with or more than 150 mg kg-1 EQ had a significantly lower growth rate compared with those fed the diet without EQ (P<0.05). There was no significant difference in SGR among fish fed the diets with or less than 50 mg kg-1 EQ content. Feed intake (FI) and feed efficiency ratio (FER) were not significantly different among dietary treatments (P>0.05). No significant differences were found in body composition among dietary treatments (P>0.05). The lipid content of fish fed diet with EQ was higher than those fed without EQ. The viscerosomatic index (VSI) and condition factor (CF) were lower in fish fed diet with EQ supplementation compared to those fed the diet without EQ. The content of eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) in the diets with EQ addition were higher than the control (0 mg kg-1), indicated that dietary EQ efficiently protect the highly unsaturated fatty acid (HUFA) from oxidizing. The HSI was significantly lower in fish fed a diet containing EQ than the diet without EQ, except that fed with 450 mg kg-1 EQ. Results of this study suggest that EQ level in diets of Japanese seabass should not exceed 50 mg kg-13. The effects of oxidized fish oil and vitamin E supplementation on the growth and antioxydant capacity, and malondialdehyde residue in tissue of large yellow croaker(Pseudosciaena crocea) were investigated. Eight experimental diets, which differed in the oxidation level of the fish oil and vitamin E supplementation included: Diet 1 (control), fresh fish oil (peroxide value (POV)=1.72 meq kg-1); Diet 2,3 and 4 oxidized fish oil (POV=28.29,62.79 and 104.21 meq kg-1, respectively). The oxidization status of fish oil in the diet 5,6,7 and 8 were the same with that in diet 1, 2,3 and,4, respectively. Vitamin E in the form of a-tocopheryl acetate was supplemented to diet 5-8 (600 IU kg-1), but not to diet 1-4. Experimental diets were fed to large yellow croaker (initial body weight 7.82±0.48 g)for 10 weeks. Survival of large yellow croaker ranged from 93.7% to 97.5% and was independent of peroxide value (POV) (P>0.05). The specific growth rate (SGR) was significantly decreased with increasing POV in oxidized fish oil (P<0.05). The SGR of fish fed the diet with fresh fish oil and without vitamin E supplementation was highest, significantly higher than those fed diets with graded levels of POV in oxidized fish oil and without vitamin E addition (P<0.05). Supplementation of vitamin E significantly improved the SGR of fish fed with oxidized fish oil, however, significantly decreased the SGR of fish fed with fresh fish oil (P<0.05). The feed intake (FI) was significantly increased with increasing POV in oxidized fish oil (P<0.05). No significant difference in feed efficiency ratio (FER) was found among dietary treatments (P>0.05). Oxidized fish oil in diets significantly decreased the lipid contents, regardless of vitamin E supplementation (P<0.05). Supplementation of vitamin E increased the lipid deposition. HSI increased with increasing POV of fish oil and decreased by the supplementation of vitamin E. The VSI of fish in groups without vitamin E addition was significantly decreased with increasing POV in oxidized oil (P<0.05). Supplementation of vitamin E decreased the VSI of fish fed without or with lower POV fish oil, and increased the VSI of that fed oxidized fish oil with higher POV.The air exposure mortality (AEM) was significantly increased with increasing POV of fish oil (P<0.05). Supplementation of vitamin E significantly decreased the AEM of fish fed diets with oxidized fish oil, but increased that in fish fed without oxidized fish oil. No significant differences in CAT and SOD were found among dietary treatments (P>0.05). The malondialdehyde (MDA) in the liver was significantly increased with the increase of POV (P<0.05), and decreased by the vitamin E supplementation. The results indicated that the supplementation of vitamin E can partially eliminate or compensate the side effects of oxidized fish oil, especially decrease the AEM. This was important to handling and transportation of fish during the commercial culture of this fish. The effect of vitamin E on performance of this fish depends on the status of dietary lipid, which should be considered when evaluating the optimal vitamin E concentration.4. The effects of oxidized dietary lipid and vitamin E supplementation on the growth and antioxidant abilities of Japanese seabass(Lateolabrax japonicus) were investigated. Eight experimental diets, which differed in the oxidation level of the fish oil and vitamin E supplementation included:Diet 1 (control), non-oxidized fish oil (peroxide value (POV)=1.72 meq kg-1); Diet 2,3 and 4 oxidized fish oil (POV =28.29,62.79 and 104.21 meq kg-1, respectively). The oxidization status of fish oil in the diet 5,6,7 and 8 were the same with that in diet 1,2,3 and 4, respectively. Vitamin E in the form of a-tocopheryl acetate was supplemented to diet 5-8 (600 IU kg-1), but not to diet 1-4. Experimental diets were fed to juvinue Japanese seabass (initial body weight 8.01±0.76 g) for 12 weeks. Survival of Japanese seabass ranged from 68.9% to 82.2% and was independent of peroxide value (POV) (P>0.05). The survival of fish fed without vitamin E addition was decreased with the increasing POV in oxidized fish oil. Supplementation of vitamin E increased the the survival of those fish fed with oxidized oil. The specific growth rate (SGR) was significantly decreased with increasing POV in oxidized fish oil (P<0.05). The SGR of fish fed the diet without oxidized oil and without vitamin E supplementation was highest, significantly higher than those fed diets with graded levels of POV in oxidized fish oil and without vitamin E addition (P<0.05). Supplementation of vitamin E significantly improved the SGR of fish fed with oxidized fish oil, however, significantly decreased the SGR of fish fed without oxidized oil (P<0.05). The feed intake (FI) was significantly increased with increasing POV in oxidized fish oil (P<0.05).No significant difference in feed efficiency ratio (FER) was found among dietary treatments (P>0.05). There were no significant differences in HIS, VSI and CF (P>0.05). CAT and SOD activities were significantly affected by the dietary treatments (P<0.05). The CAT and SOD activities significantly increased with increasing of POV in oxidized oil, regardless of vitiamin E addition (P<0.05). Supplementation of vitamin E significantly decreased the CAT and SOD activities of fish fed with oxidized fish oil, however, significantly increased the SOD activities of fish fed without oxidized oil (P<0.05). The malondialdehyde (MDA) in the liver was significantly increased with the increase of POV (P<0.05), and significantly decreased by the vitamin E supplementation (P<0.05). The results indicated that the supplementation of vitamin E can partially eliminate or compensate the side effects of oxidized fish oil, improve the growth of Japanese seabass whose diet containing oxidized lipid. The effect of vitamin E depends on the status of dietary lipid, which should be considered when evaluating the optimal vitamin E concentration.5. The effects of chromium on survival, growth of large yellow croaker and the residues of chromium in tissues were studied. Seven experimental diets were formulated containing greaded levels of chromium (in the form of chromium Polynicotinate). The experimental diets including:Diet 1 (45% crude protein) and Diet 2 (42% crude protein) were served as the control, both without chromium supplementation; the dietary protein content of Diet 3,4,5,6 and 7 were 42%, the chromium addition levels were 5,10,20,40,80 mg kg-1, respectively. The experimental diets were fed to juvenile large yellow croaker for 10 weeks. Survival of large yellow croaker, ranged from 92.0% to 97.4%, was significantly affected by addition of chromium (P<0.05). The highest survival was observed in group with 5 mg kg-1 chromium, significantly higher than the other treatments (P<0.05). The specific growth rate (SGR) was significantly affected by dietary chrorium (P<0.05). SGR decreased with the increase of chromium supplementation. The highest SGR was observed in group with 5 mg kg-1 chromium, significantly higher than the other treatments (P<0.05).The feeding intake (FI) was generally increased with increasing dietary chromium. The FI of fish fed diets with 5 and 10 mg kg-1 chromium was significantly lower than the control group at lower dietary protein level (42%). The feed efficiency ratio(FER) of fish in the groups with 5 and 10 mg kg-1 chromium addition was significantly higher than the control group at 42% protein level (P<0.05). Both lipid and ash content were significantly affected by the supplementation of chromium (P<0.05). The lipid content of fish in the groups with chromium addition was significantly higher than the control groups (P<0.05). The highest value of lipid content was observed in the groups with 40 mg kg-1 chromium supplementation. The moisture of fish generally decreased, while the protein content increased with increasing dietary chromium though no significant differences were observed. The mortality of large yellow croaker challenged by parasite was significantly decreased when fed diets with chromium addition, and the lowest value was observed in group with 5 mg kg-1 chromium. The residues of chromium in the whole body, muscle, liver and skin of large yellow croaker were significantly increased with increasing of dietary chromium (P<0.05). The residues patterns of chromium were in the order: skin> liver> whole body> muscle. The results indicated that the chromium in the diet improved the growth, feed utilization and the resistance of large yellow croaker to parasite challenging. Based on the results of SGR, the optimum chromium addition in the diet of large yellow croaker was estimated to be 5 mg kg-1.6. The effects of chromium on survival, growth of Japanese seabass and the residues were studied. Seven experimental diets were formulated containing greaded levels of chromium (in the form of chromium Polynicotinate). The experimental diets including:Diet 1 and Diet 2 were srevred as control, the dietary protein content was about 45% and 42% respectively, both without chromium supplementation; the dietary protein content of Diet 3,4,5,6 and 7 were 42%, the chromium addition levels were 5,10,20,40,80 mg kg-1, respectively. The experimental diets were fed to juvenile Japanese seabass for 10 weeks. Survival of Japanese seabass, ranged from 93.1% to 97.1%, was not significantly affected by addition of chromium (P>0.05). The survival of seabass generally increased with the increasing of dietary chromium supplementation. The specific growth rate (SGR) was significantly affected by dietary chromium (P<0.05). The SGR of fish fed diet of 5 mg kg-1 chromium was highest. SGR decreased with the increasing of chromium supplementation.The growth of fish in the groups with 5 and 10 mg kg-1 chromium supplementation was significantly higher than the control groups (P<0.05). The feeding intake (FI) was generally increased with increasing dietary chromium. The FI of fish fed diets with 5 and 10 mg kg-1 chromium was significantly lower than the control group at lower dietary protein level (42%). The feed efficiency ratio (FER) was significantly improved by the supplementation of chromium (P<0.05). The feed efficiency ratio (FER) of fish in the groups with 5 and 10 mg kg-1 chromium addition was significantly higher than the control group at 42% protein level (P<0.05). The protein, lipid and ash content of seabass were significantly affected by the supplementation of chromium (P<0.05). The protein content of the seabass fed diets with chromium was significantly higher than the control group at 42% protein level (P<0.05). The lipid content of fish in the groups with chromium addition was significantly higher than the control groups (P<0.05). The highest value of lipid content was observed in the groups with 40 mg kg-1 chromium supplementation. The ash content of fish in the groups with chromium was significantly higher than the control groups at 42% protein level (P<0.05). The moisture of fish generally decreased with increasing dietary chromium though no significant differences were observed. The residues of chromium in the whole body, muscle, liver and skin of Japanese seabass were significantly increased with increasing of dietary chromium (P<0.05). The residues patterns of chromium were in the order:liver> skin> whole body> muscle. The results indicated that the chromium in the diet improved the growth and feed utilization of Japanese seabass. Based on the results of SGR, the optimum chromium addition in the diet of Japanese seabass was estimated to be 5 mg kg-1.