Antioxidant status of serum,muscle, intestine and hepatopancreas for fish fed graded levels of biotin

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.     

Effect of dietary garlic supplementation on lipid peroxidation and protein oxidation biomarkers of tissues as well as some serum biochemical parameters in common carp Cyprinus carpio

This study aims to investigate the effects of dietary garlic powder (25 and 50 g kg^?1 feed) supplementation for 6 weeks on lipid and protein oxidation biomarkers in various tissues as well as some blood biochemical parameters in common carp. Based on the present study results, serum malondialdehyde (MDA) concentrations were decreased following garlic supplementation, but the decrease was only significant (P < 0.05) in the group that received 50 g kg^?1 dietary garlic compared with the control group. Moreover, garlic at 50 g kg^?1 diet caused significant decrease in MDA values of liver and kidney. Additionally, the decreasing effect of garlic at 25 g kg^?1 diet on MDA values was only significant in liver. Protein carbonyl contents were only decreased significantly in muscle following garlic administration at 25 g kg^?1 diet. Serum aspartate aminotransferase activity decreased significantly in carp that received 25 g kg^?1 dietary garlic. Moreover, alkaline phosphatase activity decreased significantly in carp fed diets containing 25 and 50 g kg^?1 garlic. On the other hand, garlic supplementation had no significant effect on gamma-glutamyl transferase activity and total protein, albumin, and creatinine concentrations. The results of the present study indicate that garlic powder has potential to decrease oxidative stress to some extent by reducing lipid and protein oxidation in some tissues of common carp.     

Effect of dietary lysine on growth,intestinal enzymes activities and antioxidant status of sub-adult grass carp (Ctenopharyngodon idella)

The dietary lysine requirement of sub-adult grass carp (460 ± 1.5 g) was assessed by feeding diets supplemented with grade levels of lysine (6.6, 8.5, 10.8, 12.9, 15.0 and 16.7 g kg^?1 diet) for 56 days. The test diets (28 % CP) contained fish meal, casein and gelatin as sources of intact protein, supplemented with crystalline amino acids. Weight gain (WG), feed intake and feed efficiency were significantly improved with increasing levels of lysine up to 12.9 g kg^?1 diet and thereafter declined (P < 0.05). Quadratic regression analysis of WG at 95 % maximum response indicated lysine requirement was 10.9 g kg^?1 diet. Activities of trypsin, chymotrypsin, lipase, Na⁺, K⁺-ATPase and alkaline phosphatase in intestine, creatine kinase activity in proximal and mid-intestine responded similar to WG (P < 0.05). In addition, lipid and protein oxidation decreased with increasing levels of lysine up to certain values and increased thereafter (P < 0.05); the anti-hydroxyl radical capacity, dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase (GST) activities and glutathione content were increased with increasing dietary lysine levels up to certain values in the detected tissues, except for hepatopancreatic GST. Requirement estimated on the basis of malondialdehyde content in intestine and hepatopancreas was 10.6 and 9.53 g lysine kg^?1 diet, respectively.     

Dietary taurine can improve the hypoxia-tolerance but not the growth performance in juvenile grass carp Ctenopharyngodon idellus

This study was conducted to evaluate the effects of dietary taurine, as a feed additive, on the hypoxia-tolerance and growth performance of the juvenile grass carp Ctenopharyngodon idellus, one of the most important and intensively cultured freshwater fish, with the largest production in China. Graded levels of taurine (0, 0.5, 1, 1.5, 2 and 2.5 g kg^–1 dry diet) were fed to grass carp juveniles (mean weight: 5.26 ± 0.03 g) for 8 weeks. The survival time during acute hypoxia increased as dietary levels of taurine increased, with the highest dose of taurine resulting in the best acute hypoxia-tolerance. The erythrocyte osmotic fragility in grass carp was significantly improved when dietary taurine level was at least 1.5 g kg^?1 diet and can be improved much more when dietary taurine level was up to 2.5 g kg^?1 diet. A significant correlation between hemolysis rate of the erythrocyte osmotic fragility test and the survival time of acute hypoxia (r = ?0.873, P = 0.023 < 0.05) strongly suggested that the biomembrane stabilization function of taurine may contribute to its role of enhancing acute hypoxia-tolerance in grass carp. Dietary taurine cannot improve growth performance of grass carp, but it can increase the value of mesenteric fat index, indicating that dietary taurine influences the lipid metabolism. This study provides valuable information to improve hypoxia-tolerance of grass carp.     

Effects of Bacillus preparations on immunity and antioxidant activities in grass carp (Ctenopharyngodon idellus)

This experiment was conducted to study the effects of Bacillus preparations on immunity and antioxidant activities in grass carp. A total of 315 grass carp, with similar initial weight (average weight of fish 45?g), were randomly divided into three groups with three replicates. The control group was fed the basal diet without Bacillus; treatment group 1 was added Bacillus preparation no. 1 with 1?×?10⁸?cfu/m³ per 7?days in culture water and also fed the basal diet; treatment group 2 was fed the basal diet mixed with 0.5?% Bacillus preparation no. 2, and the culture water was added 1?×?10⁸?cfu/m³ Bacillus preparation no. 1 per 7?days. After 4?weeks of culture, 12 grass carp from each replicate were taken randomly for the determination of immune response and oxidization resistance indices. The results showed that compared with control, the level of globulin and IgM of treatment group 2 was significantly increased (P?<?0.05), which was also significantly higher (P?<?0.05) than that of group 1. For the non-specific immunity index, compared with control, the lysozyme activity and complement (C3) content of treatment group 1 significantly increased (P?<?0.05), and the level of myeloperoxidase and C3 of treatment group 2 was significantly higher (P?<?0.05) than that of control, which was also significantly higher (P?<?0.05) than that of group 1. In the serum, compared with the control, the level of total antioxidant activity (T-AOC), antisuperoxide anion free radical (ASAFR) and glutathione (GSH) of two treatment groups was significantly increased (P?<?0.05); GSH content of treatment group 2 was significantly (P?<?0.05) higher than that of treatment group 1 and control. There was no significant difference between T-AOC and ASAFR among the two treatment groups; no significant effect was found on glutathione peroxidase (GSH-Px) and maleic dialdehyde (MDA) among the three groups. In the liver, T-AOC, SOD, ASAFR, GSH-Px and GSH from two treatment groups were significantly higher (P?<?0.05) than those of control; T-AOC, SOD and catalase from treatment group 2 were significantly higher (P?<?0.05) than those of treatment group 1; and MDA of two treatment groups was significantly decreased (P?<?0.05) as compared with the control. The results indicate that Bacillus preparations added into water can increase serum immunoglobulin levels and most of non-specific immune parameters content and enhance the antioxidant ability of grass carp, while adding Bacillus preparation into the water and feed is much better.     

Quantitative dietary isoleucine requirement of juvenile Pacific white shrimp,Litopenaeus vannamei (Boone) reared in low-salinity water

This study was designed to determine the isoleucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50–0.70 g L^?1). Six diets were formulated to contain 410 g kg^?1 crude protein with fish meal, peanut meal and pre-coated crystalline amino acids with different concentration of l-isoleucine (9.35, 11.85, 14.35, 16.85, 19.35, and 21.85 g kg^?1 dry diet, defined as diet I1, diet I2, diet I3, diet I4, diet I5 and diet I6, respectively.). Each diet was randomly assigned to triplicate treatments of 30 shrimps (0.43 ± 0.005 g), and the feed trial lasted for 8 weeks. The results indicated that the weight gain significantly increased with increasing isoleucine concentration up to 14.35 g kg^?1 (diet I3), whereas it was reduced in the treatments exceeding 16.85 g kg^?1 isoleucine (diet I4) significantly (P < 0.05). Moreover, the highest body protein deposition and protein efficiency ratio, and the lowest feed conversion ratio, haemolymph aspartate aminotransferase and alanine aminotransferase activities were also found at treatment I3–I4 (P < 0.05). And the haemolymph urea nitrogen concentration of shrimps-fed diet I6 was particularly higher than those fed with diets I1–I5 (P < 0.05). The results of polynomial regression based on weight gain, feed efficiency and body protein deposition indicated that the optimal dietary isoleucine requirement for L. vannamei reared in low-salinity water was 15.95 g kg^?1 isoleucine of dry diet, correspondingly 38.81 g kg^?1 of dietary protein.     

Growth performance and color enhancement of goldfish,Carassius auratus,fed diets containing natural dyes extracted from annatto (Bixa orellana) seeds

ABSTRACT

The present study was conducted to evaluate growth performance and color enhancement of goldfish, Carassius auratus, fed diets containing 0, 50, 100, 200, and 250 mg kg^?1 diet of annatto dye (AD) for 60 days. The survival rate was significantly higher in fish fed 100, 200, and 250 mg AD kg^?1 diet over than these fed control and 50 mg AD kg^?1 diet (p < 0.05). AD significantly (p <0 .05) increased the pigmentation in the skin and caudal fin of goldfish in a concentration dependent manner (R² = 0.995, 0.997). The highest amount of total carotenoid deposition in fish skin and fins were given by diets containing 200–250 mg AD kg^?1 diet. The highest redness (a*) of 43.21 and yellowness (b*) of 12.53 were obtained by 250 and 50 mg AD kg^?1, respectively. The present results show that AD can be successfully used as an alternative natural carotenoid source in goldfish diets at levels of 200–250 mg AD kg^?1 diet.     

Modulation of appetite,lipid and glucose metabolism of juvenile grass carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>) by different dietary protein levels

This study was undertaken to explore the systemic metabolic strategies of juvenile grass carp (Ctenopharyngodon idellus) to maintain growth when fed with different dietary protein levels. The optimal growth group and two growing discomfort groups were selected through the basic data, to explain the growth difference from appetite regulation and lipid and glucose metabolism perspective. Three experimental diets were formulated with three dietary protein levels at 200.3, 296.1 and 442.9 g kg^?1, named P1, P2 and P3, respectively. Juvenile grass carp (initial body weight 12.28 ± 0.14 g) were fed with three diets with 3 replications per dietary treatment in an indoor recirculation system for an 8-week feeding trial. Fish fed with diet P2 dietary group showed significantly higher WG, SGR, FI and PER than other groups. Compared with other groups, mRNA expressions of NPY, Y8a and Y8b in fish fed with P2 significantly down-regulated, while the expressions of CCK and CART in fish fed with P3 significantly down-regulated (P < 0.05). With increasing dietary protein levels, G6Pase, GK, PK and PEPCK were all significantly inhibited (P < 0.05). For lipid metabolism, the mRNA expression of ACC in P1 dietary group was significantly higher than P3 dietary group; besides, LPL expression in P3 group was significantly higher than other two groups (P < 0.05). PPARα expression in P2 was significantly lower than other groups (P < 0.05). These results suggested that grass carp fed with P2 (296.1 g kg^?1 protein level) showed highest weight gain, contributed to more balanced nutrient metabolism and appetite regulation. Too high dietary protein (442.9 g kg^?1) should be avoided because it induced lowest PER, body lipid and liver lipid, and inhibited glucose and lipid metabolism in juvenile grass carp.     

The improvement of growth,digestive enzyme activity and disease resistance of white shrimp by the dietary citric acid

A 45-day feeding trial was conducted to evaluate the effects of dietary citric acid on growth, digestive enzyme and disease resistance of white shrimp, Litopenaeus vannamei. Shrimp with initial body weight of 5.57 ± 0.21 g were fed with basal diet supplemented with 0.0 g kg^?1 (control), 1.0, 2.0, 3.0, 4.0 and 5.0 g kg^?1 citric acid. Results showed that weight gain was increased by 15.9 % and feed conversion ratio was decreased by 0.17 by 2.0 g kg^?1 dietary citric acid compared with control group (P < 0.05). Intestinal protease activity of shrimp fed 2.0 g kg^?1 citric acid was significantly higher (P < 0.05) than that of control group. No significant difference was found in intestinal amylase activity among treatments (P > 0.05). The activities of serum phenoloxidase, superoxide dismutase and lysozyme in 2.0 and 3.0 g kg^?1 citric acid group were significantly higher, and accumulative mortalities of the two groups on the fourth day after injection of Vibrio alginolyticus were significantly lower than those of control group (P < 0.05). Results above demonstrated that dietary citric acid could improve growth performance, immunity and resistance against V. alginolyticus. The supplementation level of citric acid in diet was suggested to be 2.0–3.0 g kg^?1 for white shrimp.     

Hemato-immunological responses of Heros severus fed diets supplemented with different levels of Dunaliella salina

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.     

Effect of dietary chitosan on growth performance,hematological parameters,intestinal histology and stress resistance of Caspian kutum (<Emphasis Type="Italic">Rutilus frisii kutum</Emphasis> Kamenskii, 1901) fingerlings

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.     

The effects of dietary thiamin on oxidative damage and antioxidant defence of juvenile fish

The present study explored the effects of thiamin on antioxidant capacity of juvenile Jian carp (Cyprinus carpio var. Jian). In a 60-day feeding trial, a total of 1,050 juvenile Jian carp (8.20 ± 0.02 g) were fed graded levels of thiamin at 0.25, 0.48, 0.79, 1.06, 1.37, 1.63 and 2.65 mg thiamin kg^?1 diets. The results showed that malondialdehyde and protein carbonyl contents in serum, hepatopancreas, intestine and muscle were significantly decreased with increasing dietary thiamin levels (P < 0.05). Conversely, the anti-superoxide anion capacity and anti-hydroxyl radical capacity in serum, hepatopancreas, intestine and muscle were the lowest in fish fed the thiamin-unsupplemented diet. Meanwhile, the activities of catalase (CAT), glutathione peroxidase, glutathione S-transferase and glutathione reductase, and the contents of glutathione in serum, hepatopancreas, intestine and muscle were enhanced with increasing dietary thiamin levels (P < 0.05). Superoxide dismutase (SOD) activity in serum, hepatopancreas and intestine followed a similar trend as CAT (P < 0.05). However, SOD activity in muscle was not affected by dietary thiamin level (P > 0.05). The results indicated that thiamin could improve antioxidant defence and inhibit lipid peroxidation and protein oxidation of juvenile Jian carp.     

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

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

Stimulatory effect of dietary taurine on growth performance,digestive enzymes activity,antioxidant capacity,and tolerance of common carp, <Emphasis Type="Italic">Cyprinus carpio</Emphasis> L., fry to salinity stress

The present study was carried out to evaluate the effect of dietary taurine (Tau) on performance, digestive enzymes, antioxidant activity, and resistance of common carp, Cyprinus carpio L., fry to salinity stress. Fish (0.97?±?0.033 g) were fed on different taurine levels of 0.0 (control), 5, 10, 15, or 20 g/kg diet up to satiation twice daily for 8 weeks. At the end of the feeding trial, fish were stressed by exposure to 10 ppt salinity for 3 days during which fish mortality was observed. Fish performance was significantly (P?<?0.05) improved by dietary taurine up to 15 g Tau/kg diet after which fish growth and feed intake were almost the same. Also, taurine supplementation significantly (P?<?0.05) elevated activities of intestinal amylase, lipase, and protease resulting in an improving in feed intake giving better performance. Furthermore, Tau-stimulated antioxidant activity of common carp was observed in a dose-related manner, where activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly (P?<?0.05) higher, but malondialdehyde (MDA) value was significantly (P?<?0.05) lower in Tau-fed fish groups than those fed the control diet. In salinity stress experiment, highest survival rate was observed at fish fed Tau-supplemented diets without significant (P?>?0.05) differences over fish fed the control diet. It appears that taurine could be used as a feed supplement to confer better growth and health of common carp fry with optimal level of 15 g/kg diet.     

Effects of dietary organic,inorganic, and nanoparticulate selenium sources on growth,hemato-immunological,and serum biochemical parameters of common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis>)

An 8-week feeding trial was conducted to compare the effects of supplementing (0.7 mg kg^?1) different dietary selenium (Se) sources including organic [selenomethionine (SeMet)], inorganic [sodium selenite (Na₂SeO₃)], and nanoparticulate Se (nano-Se) on physiological responses of common carp, Cyprinus carpio juveniles (9.7?±?0.1 g). Basal diet without Se supplementation used as control. Fish fed nano-Se supplemented diet had the highest weight gain (97.2?±?10.8%) and feed efficiency ratio (42.4?±?0.8%). Intestinal villi height was significantly taller in fish fed nano-Se diet than in the control group in both foregut and midgut sections. Serum glutathione peroxidase and superoxide dismutase activities were significantly higher in nano-Se and SeMet groups than in control and sodium selenite groups. Fish fed Se-supplemented diets had greater red blood cell counts and hematocrit and hemoglobin values than the control group (P?<?0.05). Nano-Se and SeMet groups showed a significant increase in white blood cell counts, neutrophil percentage, and serum lysozyme activity than the other groups. Fish fed nano-Se diet had the highest serum hemolytic activity, total immunoglobulin, and total protein and albumin contents, as well as the lowest serum total cholesterol and low density lipoprotein levels (P?<?0.05). Overall, significant improvements in growth performance, feed utilization, intestinal morphology, and hemato-immunological and serum biochemical parameters of common carp juveniles suggest nano-Se as an efficient source for providing dietary Se in this species.     

Effects of dietary astaxanthins on pigmentation of flesh and tissue antioxidation of rainbow trout (Oncorhynchus mykiss)

The present study was conducted to evaluate the effects of three commercial astaxanthin preparations (100 mg kg^?1 diet) with different solubilities in water, from DSM (Dutch State Mines), BASF (Badische Anilin and Soda Fabrik) and Wisdom Company on pigmentation of flesh and antioxidation of flesh, serum and liver in rainbow trout with an initial weight of 52.07 g. After 60 days of feeding, there were no significant differences in growth or flesh proximate composition of rainbow trout among groups (P > 0.05); the Salmo Fan score, redness and astaxanthin content of flesh in rainbow trout fed diets supplemented with astaxanthins were higher than those of the control group (P < 0.05). At 0, 12, 24, 48 and 72 h after thawing, the flesh malondialdehyde (MDA) content of the three astaxanthin groups was lower than that of the control group (P < 0.05). The total antioxidation capacity (T-AOC) of liver in the three astaxanthin groups was significantly higher, but serum catalase (CAT) activities were lower, than that of the control group (P < 0.05). The results indicate that addition of 100 mg kg^?1 astaxanthin from DSM, BASF or Wisdom to the diet could improve flesh redness and liver T-AOC, reduce serum CAT, SOD and flesh MDA and extend the shelf life of flesh, in spite of the different solubilities of the three sources in water.     

Dietary protein and carbohydrate requirement of juvenile Hawaiian limpet (<Emphasis Type="Italic">Cellana sandwicensis</Emphasis> Pease, 1861) fed practical diet

This study was conducted to evaluate dietary protein and carbohydrate requirement of juvenile Hawaiian limpets Cellana sandwincensis. A total of 64 juvenile limpets (3.12 ± 0.86 g) were fed five different dietary protein levels ranging from 270 to 470 g kg^?1 for 90 days. Carbohydrate and lipid levels were held constant at 180 and 49.7 g kg^?1, respectively. Weight gain and growth rates of the animals did not differ significantly (P > 0.05) among the protein levels ranging from 270 g kg^?1 (0.30 % day^?1) to 470 g kg^?1 (0.23 % day^?1). Next, opihi were fed four diets with protein levels from 210 to 500 g kg^?1 with a constant carbohydrate level at 120 g kg^?1. Weight gain and specific growth rates of opihi increased with increasing dietary protein from 210 to 350 g kg^?1, and significantly (P < 0.05) decreased at the 500 g kg^?1 diet. Highest weight gain, growth rates, and protein efficiency ratio were achieved at 350 g kg^?1. Elevated carbohydrate levels (180–370 g kg^?1) produced a significant difference (P < 0.05) in growth. The fastest growth rates of animals were obtained with 270 g kg^?1 (0.27 % day^?1) and 320 g kg^?1 (0.26 % day^?1). The weight gain of animals fed 180 and 370 g kg^?1 carbohydrate diets were significantly (P < 0.05) lower than those of animals fed 270 and 320 g kg^?1. We conclude that about 350 g kg^?1 protein and 320 g kg^?1 carbohydrate levels could be used for opihi.     

Effect of prebiotic konjac mannanoligosaccharide on growth performances,intestinal microflora,and digestive enzyme activities in yellow catfish,Pelteobagrus fulvidraco

In the present study, konjac mannanoligosaccharide (KMOS) was evaluated as a prebiotic in yellow catfish. The fish were fed with diets containing KMOS in four concentrations: 0 g kg^?1 (C), 1.0 g kg^?1 (KM1), 2.0 g kg^?1 (KM2), and 3.0 g kg^?1 (KM3) for 49 days, respectively. Another group fed with diets containing 3.0 g kg^?1 yeast cell wall mannanoligosaccharide (MOS) (M3) was set as positive control. The results indicated that fish receiving the diets supplemented with KMOS or MOS showed higher relative gain rate (RGR), specific growth rate (SGR), and lower feed conversion ratio (FCR) with significantly differences (P < 0.05) than those fed with the basal diets. Moreover, fish receiving the diets with 2.0 g kg^?1 KMOS inclusion showed higher RGR, SGR, and lower FCR (P < 0.05) than that feeding the diets supplemented with 3.0 g kg^?1 MOS. The quantities of Bifidobacterium spp. were significantly increased (P < 0.05). Meanwhile, Escherichia coli and Aeromonas spp. were significantly reduced (P < 0.05) in the fish-feeding diets with 2.0 g kg^?1 KMOS supplement. Compared with the control group, the significantly enhancement of protease and amylase activity (P < 0.05) in intestine and pancreas was observed in fish fed with diets containing KMOS or MOS. Collectively, an optimum level of KMOS inclusion in diets could modulate intestinal microflora, induce digestive enzyme activity, and improve the growth performance of yellow catfish significantly.     

Growth performance and immune responses of gibel carp, <Emphasis Type="Italic">Carassius auratus gibelio</Emphasis>, fed with graded level of rare earth-chitosan chelate

A 12-week feeding trail was conducted to assess the effect of rare earth-chitosan chelate (RECC) on growth performance and immune responses of gibel carp, Carassius auratus gibelio. Isonitrogenous and isolipid experimental diets were supplemented with graded levels of rare earth-chitosan chelate (RECC 0, 0.8, 4 and 8 g Kg^?1). A total of 720 gibel carps (initial body weight about 14.32 g) were divided randomly into four groups with six replicates, respectively. Fish were fed with the experimental diets three times every day. At the end of the feeding trail, the survival rate was higher than 96 %. Weight gain rate and specific growth rate (SGR) significantly increased with RECC supplementation up to 0.8 g Kg^?1 (P < 0.05) and tended to decline at higher supplementation levels, while feed conversion ratio was not significantly different between groups (P > 0.05). Based on broken-line regression analysis of SGR, the optimum dietary RECC was estimated to be 0.71 g Kg^?1 of the diet. Condition factor and viscerosomatic index were not significantly affected by RECC (P > 0.05), while hepatosomatic index in the group fed with 0.8 g Kg^?1 RECC (3.45 ± 0.10 %) was significantly lower than in other groups (P < 0.05). Plasma ALT was significantly affected by RECC (P < 0.05), while AST was not. Plasma total protein and albumin were increased with RECC supplementation up to 0.8 g Kg^?1 and decreased significantly at higher supplementation levels (P < 0.05). RECC supplementation significantly decreased plasma urea and glucose concentration and increased plasma creatinine concentration significantly (P < 0.05). Respiratory burst activity of phagocytes and myeloperoxidase activity were not significantly different between groups, while superoxide dismutase activity and nitrogen monoxide concentration were increased with the increasing level of RECC in the diets. In conclusion, RECC could enhance growth performance and improve immunity of gibel carp.     

Effects of practical dietary protein to lipid levels on growth,digestive enzyme activities and body composition of juvenile rice field eel (Monopterus albus)

A 10-week feeding experiment was conducted to evaluate the effects of dietary protein to lipid ratios (P/L) on growth, intestinal digestive enzyme activities and body composition in juvenile rice field eel (Monopterus albus) (initial mean body weight of 65.76 ± 1.07 g, mean ± SEM). Nine test diets were formulated in a 3 × 3 factorial design to contain three protein levels (350, 400 and 450 g kg^?1) for each of three lipid levels (40, 80 and 120 g kg^?1), respectively. Each diet was randomly assigned to triplicate groups of 60 fish per net cage (1.5 × 2.0 × 1.5 m). Results showed the survival was above 96 % and was not affected by dietary treatments. Fish fed the diet with 450 g kg^?1 protein and 40 g kg^?1 lipid showed the best weight gain (WG) (103.95 %) and feed conversion ratio (1.60) (P < 0.05). WG, protein efficiency ratio and energy retention increased with the increasing in lipid at 350 g kg^?1 protein level (P < 0.05). However, WG showed a little decline with increasing dietary lipid when fish fed the diets with 400 and 450 g kg^?1 protein level, but no significant difference was observed (P < 0.05). Hepatosomatic index, visceralsomatic index and intestinal lipase activity increased with the increasing of dietary lipid level irrespective protein level. Intestinal trypsin activity increased with the increasing of dietary lipid level when fish fed the diets with 350 g kg^?1 protein, but showed converse trend when fish fed the diets with 400 and 450 g kg^?1 protein. Serum triglyceride, body lipid and energy were positively correlated with the dietary lipid. Results of the present study showed that the dietary protein/lipid ratio of 450/40 g kg^?1 is considered optimum for rice field eel under culture conditions, and the increase in dietary lipid level has no efficient protein-sparing effect when fish fed the diets with 400 and 450 g kg^?1 protein level.