Effects of varying levels of dietary vitamin E (α‐tocopherol) on growth performance,proximate and fatty acid composition of juvenile silver pomfret (Pampus argenteus Euphrasen, 1788)

This study investigated the effects of elevated dietary levels of vitamin E (α‐tocopherol) on growth performance, proximate composition and fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Three semi‐purified experimental diets were formulated to contain 49% protein and 16% lipid. High docosahexaenoic acid (DHA) tuna oil was added to the diets to supplement DHA. A graded level of vitamin E (0‐, 50‐, and 100 mg kg^?1) was added to experimental diets 1 to 3, respectively. Analyzed vit. E levels were 155.2, 195.3 and 236.4 mg kg^?1 in diets 1, 2 and 3, respectively. The experiment was conducted for 12 weeks with juvenile silver pomfret (29.6 ± 7.6 g) using a flow‐through system consisting of nine 1‐m³ tanks. Each treatment had three replicates and fish were stocked at the rate of 20 m^?3. Growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P < 0.05) higher than in fish fed diet 1, but the parameters in diets 2 and 3 did not differ significantly (P > 0.05). Although whole body protein levels were not influenced by the dietary vit. E levels, whole body lipid in fish fed diet 2 was significantly higher than in fish fed the other diets. The whole body vit. E levels in fish fed diet 2 (22.6 mg kg^?1) and diet 3 (24.1 mg kg^?1) were significantly (P < 0.05) higher than in those fed diet 1 (18.2 mg kg^?1). Whole body total saturated fatty acids were significantly lower, and DHA levels higher in fish fed diets 2 and 3 than those fed diet 1. The results of the present study suggest that increasing dietary supplementation of vit. E in high lipid diets enhances the growth performance of fish and that a dietary level of 196 mg kg^?1 vit. E is suitable for the growth of silver pomfret.     

Effects of dietary thymol‐carvacrol on growth performance,hematological parameters and tissue composition of juvenile rainbow trout,Oncorhynchus mykiss

Growth performance, carcass quality, survival and hematological responses of Oncorhynchus mykiss juveniles (initial weight 8.4 ± 0.1 g) fed diets containing thymol‐carvacrol powder at the levels of 0, 1.0, 2.0, 3.0 g kg^?1 were tested. Thymol‐carvacrol powder originated from Origanum vulgare, a Mediterranean plant, added to diets. Each diet was fed to triplicate groups of fish for 45 days. Fish fed diets containing thymol‐carvacrol had significantly higher final weight and growth than the control group. Food conversion ratio in fish fed diets containing 2.0 and 3.0 g kg^?1 thymol‐carvacrol was statistically better than in other treatments. Survival was not different among all treatments. The number of lymphocytes increased when thymol‐carvacrol was used at higher levels. Furthermore, whole body lipid content was higher in fish fed 1.0 and 2.0 g kg^?1 thymol‐carvacrol than the other groups, but body protein in the group fed 3.0 g kg^?1 was higher than in other groups. Also, body ash in control and 1.0 g kg^?1 was higher than in other groups. Whole body dry matter was not affected by dietary treatments. These results indicated that dietary administration of thymol‐carvacrol can influence some growth, hematological parameters and tissue composition in rainbow trout juveniles.     

Coriolus versicolor polysaccharides enhance the immune response of crucian carp (Corassius auratus gibelio) and protect against Aeromonas hydrophila

To investigate the effect of Coriolus versicolor polysaccharides (CVPS) on the immune response of crucian carp (Corassius auratus gibelio), fish were fed diets containing CVPS at different concentrations including 0.5, 1.0 and 2.0 g kg^?1 for 5 weeks. Other groups of fish were vaccinated by intraperitoneal injection (i.p.) against Aeromonas hydrophila with a killed bacterin at the beginning of the experiment and fed the same diets as described above. Additionally, control fish and vaccinated‐only fish were fed basal diets without CVPS supplementation. The phagocytosis, lysozyme activity, complement components C3 and C4, E‐C3bRR (Erythrocyte‐C3b rosette rate) and E‐CIRR (Erythrocyte‐immune complex rosette rate) levels and circulating antibody titers in the serum were monitored. Five weeks after feeding the prescribed diet, fish were challenged with A. hydrophila and the mortalities recorded. Results showed that feeding non‐vaccinated and vaccinated crucian carp with CVPS stimulated the phagocytosis of leukocytes, lysozyme, complement components C3 and C4, erythrocyte immune adherence, and circulatory antibody titers in serum in vaccinated crucian carp. Immune parameters increased to their highest levels after 3 weeks of feeding the diet containing 0.5 or 1.0 g kg^?1 CVPS. These doses also resulted in the highest protection in the challenge experiment. Best survival (85%) was in the vaccinated group fed the diet containing 1.0 g kg^?1 CVPS, whereas almost 80% of control fish (negative control) and 50% of vaccinated‐only fish (positive control) died.     

Effects of dietary l‐carnitine supplements on growth and body composition in beluga sturgeon (Huso huso) juveniles

The effects of dietary l ‐carnitine on growth performance, whole body composition and feed utilization were studied in beluga, Huso huso. Fish were randomly allocated in 15 tanks (30 fish per tank) and triplicate groups were fed to satiety during 84 days one of five isonitrogenous (41% CP) and isoenergetic (20 MJ kg^?1) diets, each differing in l ‐carnitine content [0 (control), 300, 600, 900 and 1200 mg kg^?1 diet]. At the end of the trial, fish grew from 19‐ to 23‐fold in weight, from 8.4 g to a maximum of 191 g. Fish fed 300–600 mg l ‐carnitine had the highest specific growth rate (SGR, 3.69 and 3.72% day^?1) and protein efficiency ratio (PER, 0.95 and 0.99), and the lowest feed conversion ratio (FCR, 1.4 and 1.3) than the other groups (P < 0.0001). SGR, PER and FCR were the poorest for fish fed 1200 mg l ‐carnitine, while fish fed the unsupplemented and 900 mg l ‐carnitine supplemented diet showed intermediate performance. Body lipid concentration decreased significantly from 5.8 to 5.1% (P < 0.0001) with dietary l ‐carnitine supplementation increasing from 0 to 300 mg. Energy content was significantly lower in fish fed the 900 and 1200 mg l ‐carnitine diet (5.8 MJ kg^?1), when compared with the other treatment groups (6.4–6.6 MJ kg^?1). The results indicated that feeding sturgeon on diets supplemented with 300 mg l ‐carnitine kg^?1 diet improved growth performance, and stimulated protein‐sparing effects from lipids.     

Immunomodulatory effect of sodium alginate enriched diet in kelp grouper Epinephelus brneus against Streptococcus iniae

The effect of diets containing sodium alginate at 0, 0.5, 1.0, and 2.0 g kg^?1 following challenge with Streptococcus iniae in kelp grouper Epinephelus bruneus were assessed with reference to survival rate and innate immune parameters such as alternative complement, lysozyme, natural haemagglutination, respiratory burst, superoxide dismutase, and phagocytic activities on week 1, 2, and 4. Fish fed with sodium alginate containing diet at 1.0 and 2.0 g kg^?1 after being challenged with S. iniae had higher survival rates of 75% and 60%, respectively than those fed with control diet (0 g kg^?1). With any enriched diet the percentage of macrophages significantly decreased from week 1–4, while the percentage of neutrophils and lymphocytes significantly increased. The alternate complement activity, natural haemagglutination, and phagocytic activities of infected fish fed with sodium alginate containing diet at 1.0 g kg^?1 on week 2 and 1.0 and 2.0 g kg^?1 diets on week 4 were significantly higher when compared to the control. The lysozyme, respiratory bursts, and superoxide dismutase activities of fish fed with enriched diets at 1.0 and 2.0 g kg^?1 were significantly increased on week 2 and 4. We therefore recommend that at 1.0 or 2.0 g kg^?1 dietary administration of sodium alginate can enhance innate immunity and disease resistance in kelp grouper against S. iniae.     

Liver alteration and hematological and serum biochemical responses of common carp,Cyprinus carpio Linnaeus, 1758, following long‐term feeding of pistachio (Pistacia vera) green hull extract as a source of natural phenol

This study was conducted to investigate the effect of pistachio green hull extract (PGHE) on hematological and serum biochemical changes in common carp, Cyprinus carpio. Three hundred common carp (11.65 ± 1.65 g) were fed one of five different dietary treatments (with three replications) containing 0, 0.5, 1.5, 4.5 or 9 g PGHE kg^?1diet for ten continuous weeks. Each tank had a 90‐L capacity and water flow rate of about 500 ml min^_1.Total phenolic compounds of the different diets differed significantly (P < 0.001) according to the amount of PGHE. At the end of experiment, six fish were removed randomly from each treatment. Blood samples were taken for hematological and serum biochemical analyses at room temperature. Liver tissue samples were processed for histology and stained by H&E. The results indicated that all doses of tested PGHE induced no significant changes in hematocrit, hemoglobin, or erythrocytes, nor alkaline phosphatase, alanine transaminase, lactate dehydrogenase, total protein, albumin, globulin, triglycerides, low‐density lipoprotein, high‐density lipoprotein, glucose or cholesterol in the serum. Leukocytes were higher (P < 0.01) in fish fed a 1.5, 4.5, or 9 g PGHE kg^?1 diet when compared to the 0.5 g PGHE kg^?1 diet group or the control. Serum aspartate transaminase in treatments containing a 4.5 or 9 g PGHE kg^?1 diet was significantly (P < 0.001) higher in comparison with the control. Liver histology showed focal necrosis, cytoplasm degeneration, lateral nuclei and an increase in Kupffer cells following PGHE administrations. The results of this trial indicated that although there were no significant changes in most hematological and biochemical parameters, PGHE could induce some adverse pathological effects on liver tissue.     

Evaluation of optimum dietary vitamin E requirements using DL‐α‐tocopheryl acetate in the juvenile eel,Anguilla japonica

The study aimed at evaluating the optimum dietary vitamin E requirements using DL‐α‐tocopheryl acetate in the juvenile eel, Anguilla japonica, as assessed by fish growth performance and fish body composition. Five semi‐purified experimental diets were formulated to contain 0 (TA₁), 15 (TA₁₇), 30 (TA₃₂), 60 (TA₆₂) and 120 (TA₁₁₉ mg TA kg^?1 diet on a dry matter (DM) basis in the form of DL‐α‐tocopheryl acetate (TA). After a 4‐week conditioning period, fish (15 ± 0.3 g) were randomly distributed into aquaria in groups of 20 at 25 ± 1.0°C (mean ± SD). One of the five diets was fed on a DM basis to fish in three randomly selected aquaria twice daily to satiation (approximately 3% of wet body weight per day at the beginning and 2% of wet body weight per day at the end of the feeding trial) for 12 weeks. At the end of the 12‐week feeding trial, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) were determined; these were significantly lower in control fish than in fish fed supplemented diets (P < 0.05). The values for fish fed TA₁₇ were significantly higher than for fish fed TA₁, TA₆₂ or TA₁₁₉ (P < 0.05). There were no significant differences in WG, FE or PER among fish that were fed TA₁₇ and TA₃₂, among those that were fed TA₃₂ and TA₆₂, and among those that were fed TA₆₂ and TA₁₁₉ (P > 0.05). There were also no significant differences in SGR among fish fed TA₃₂, TA₆₂ or TA₁₁₉ (P > 0.05). A broken‐line regression analysis on the basis of WG, SGR, FE and PER showed that dietary vitamin E requirements of juvenile eels were 21.2, 21.6, 21.2 and 21.5 (mg kg^?1 diet), respectively. These results indicate that the dietary vitamin E requirement could be <21.2 mg kg^?1 but <21.6 mg kg^?1 diet in juvenile eel, A. japonica, when DL‐α‐tocopheryl acetate is used as the dietary vitamin E source.     

Partial replacement of monocalcium phosphate with neutral phytase in diets for grass carp,Ctenopharyngodon idellus

A 9‐week experiment was designed to study the effects of partial replacement of monocalcium phosphate (MCP) with neutral phytase on growth, body compositions, serum biochemical statuses and intestinal digestive enzyme activities of grass carp, Ctenopharyngodon idellus. The control diet (designated as P2.0) was prepared with 2.0% MCP but without phytase. The three other diets (designated as PP1.5, PP1.0 and PP0.5, respectively) were supplemented with 1.5, 1.0 and 0.5% MCP, respectively, along with 500 FTU of neutral phytase kg^?1 diet in each. After a 9‐week feeding trial, fish (initial body weight: 43.44 ± 2.37 g) fed with PP1.5 and PP1.0 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared with the control (P > 0.05) whereas fish fed with PP0.5 showed significantly lower growth performance in the above parameters. The crude lipid content in whole body or muscle of the fish fed with PP1.5 was significantly lower than the control while significantly higher in fish fed with PP0.5 (P < 0.05), whereas no obvious change was observed in the fish fed with PP1.0. For serum indices, higher serum alkaline phosphatase (Alkp), phosphorus (P) and calcium (Ca) contents were observed in fish fed with phytase‐supplemented diets in comparison with the control. In addition, dietary phytase supplementation increased amylase activity and decreased lipase activity in both foregut and hindgut. The present study suggests that dietary MCP can be reduced when neutral phytase is added to the grass carp diet, and that the maximum MCP reduction level can be up to 1% when neutral phytase is supplemented at 500 FTU kg^?1 diet.     

Dietary total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Indian major carp: Cirrhinus mrigala (Hamilton) fingerlings

Two 8‐week growth trials were conducted to determine total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Cirrhinus mrigala fingerlings. To determine the phenylalanine requirement, 20 fish were randomly stocked in triplicate groups in 55‐L indoor polyvinyl flow‐through circular tanks and fed six experimental diets containing graded levels of phenylalanine (5.0, 7.5, 10.0, 12.5, 15.0 and 17.5 g kg^?1, dry diet) with 10 g kg^?1 tyrosine. Maximum weight gain (287%), best FCR (1.44) and PER (1.74) occurred at 12.5 g kg^?1 dietary phenylalanine. Quadratic regression analysis of weight gain, FCR and PER data indicated phenylalanine requirement at 13.5, 12.9 and 12.7 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 12.5 g kg^?1 dietary phenylalanine. Based on the above results, phenylalanine requirement of C. mrigala is recommended at 13.0 g kg^?1 of dry diet, corresponding to 32.5 g kg^?1 of protein. On the basis of the above requirement, a second experiment with a similar design was conducted using six diets containing graded levels of tyrosine (2.1, 4.0, 6.0, 8.0, 10.0 and 12.0 g kg^?1) with 13.0 g kg^?1 phenylalanine fixed in all diets to determine the phenylalanine replacement value with that of tyrosine. Maximum weight gain (315%), best FCR (1.47) and PER (1.69) was at 8.0 g kg^?1 dietary tyrosine. Quadratic regression analysis of weight gain, FCR and PER data indicated tyrosine requirement at 9.0, 8.4 and 8.2 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 8.0 g kg^?1 dietary tyrosine. On the basis of the above results, 8.5 g kg^?1 tyrosine, corresponding to 21.3 g kg^?1 of protein, is taken as the optimum requirement and the replacement value is 39.53% on a weight and 36% on a molar basis. Thus, the total aromatic amino acid requirement is 21.5 g kg^?1 of diet, corresponding to 53.8 g kg^?1 of protein for optimum C. mrigala growth.     

Lysine and arginine requirements of juvenile Asian sea bass (Lates calcarifer)

Two separate experiments were conducted to determine the dietary requirements of juvenile Asian sea bass Lates calcarifer Bloch for lysine and arginine. Fish (average initial weight: lysine experiment, 13.12 ± 0.12 g; arginine experiment, 2.56 ± 0.13 g) were given amino acid test diets for 12 weeks containing fish meal, zein, squid meal, and crystalline amino acids. Each set of isonitrogenous and isocaloric test diets contained graded levels of L ‐lysine or L ‐arginine. The feeding rate in the lysine experiment was at 4–2.5% of the body weight day^?1, while in the arginine experiment it was at 10–4% of the body weight day^?1. The fish (20 per tank, lysine experiment; 15 per tank, arginine experiment) were reared in 500‐L fibreglass tanks with continuous flowthrough sea water at 27 °C and salinity of 31 ppt in the lysine experiment and at 29 °C and salinity of 29 ppt in the arginine experiment. The experiments were in a completely randomized design with two replicates per treatment. Survival was high in fish given adequate lysine or arginine. Mean percentage weight gains were significantly different in fish fed varying levels of lysine or arginine. Fish fed high levels of L ‐arginine suffered high mortalities. No significant differences were obtained in the feed efficiency ratios (FER, g gain g^?1 feed) of fish fed graded lysine, although the values tended to increase as the dietary lysine level was increased up to the requirement level. In contrast, in the arginine experiment, significant differences in FER of fish among treatments were obtained; the highest FER was observed in fish fed the diet containing an optimum arginine level. On the basis of the growth response, survival, and FER, the lysine and arginine requirements of juvenile Asian sea bass were estimated to be 20.6 g kg^?1 dry diet (4.5% protein) and 18.2 g kg^?1 dry diet (3.8% protein), respectively. These data will be useful in the further refinement of practical diet formulations for the Asian sea bass.     

Effect of feeding different protein to energy (P/E) ratios on the growth performance and body composition of Oreochromis niloticus fingerlings

This study evaluated the growth performance and body composition of Oreochromis niloticus fingerlings (average initial weight 16.53 ± 0.44 g) fed 9 experimental diets (A, B, C, D, E, F, G, H and I) containing three different levels of protein (26, 31 and 36 g 100 g^?1) at three different gross energy (GE) levels (16, 19 and 22 MJ kg^?1) for a period of 64 days. Significant differences were observed in the feed consumption, body weight gain, specific growth rate (SGR), condition factor (k), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparent net energy retention (ANER) values of fish when the energy level of diet was increased at different protein levels. The maximum weight gain, SGR and k were observed on diet F containing 36% protein and an energy level of 19 MJ kg^?1 of dry feed with a protein to energy (P/E) ratio of 18.96 (g protein MJ^?1 GE). A further increase in the energy content of the diet (22 MJ kg^?1) at the same protein level (Diet I) did not produce any improvement in the growth performance. Lowering the energy level at the same protein level significantly affected the growth performance. Fish fed diet B containing 31% protein and a lower energy level of 16 MJ kg^?1 with the same P/E ratio of 18.61 as diet F showed significantly lower weight gain and growth performance than diet F. Diets E and H containing 31% crude protein at all three energy levels produced similar results as diet B. The poorest FCR was observed when the diet contained both lower levels of protein and energy. Fish fed diet G, containing 26% protein at high energy level (22 MJ kg^?1), showed the best PER and NPR values. The PER and NPR were the poorest on diet C containing 36% protein at low energy level (16 MJ kg^?1). The body moisture content at all protein levels decreased (P < 0.05) with the increasing level of dietary energy whereas the body fat content increased (P < 0.05). Similar trends were observed in the body ash and energy content. Increasing the dietary energy content at lower protein levels did not show any difference (P > 0.05) in body protein content. Our results indicated the optimum P/E ratio for O. niloticus as 18.96 g protein per mega joule of gross energy at 36% dietary protein level and a dietary gross energy value of 19 MJ kg^?1.     

Effect of dietary dextrin levels on the growth performance,blood chemistry,body composition,hepatic triglicerides and glycogen of Lebranche mullet juveniles (Mugil liza Valenciennes 1836, Mugilidae)

The effects of increasing levels of dietary dextrin on growth performance, body composition, blood chemistry and hepatic triglycerides and glycogen levels were evaluated for juvenile Lebranche mullet, Mugil liza Valenciennes 1836, Mugilidae). Five diets were formulated to be isonitrogenous (350 g kg^?1) and isolipidic (6 g kg^?1) with increasing dextrin levels (D150: 150 g kg^?1; D200: 200 g kg^?1; D250: 250 g kg^?1; D300: 300 g kg^?1; D350: 350 g kg^?1). The experimental diets were offered to the fish for 34 days, four times per day, until apparent satiation. Each treatment was tested in triplicate, with nine fish per tank (mean weight 4.69 ± 0.31 g). Fish were reared in a recirculating aquatic system of 15 fibreglass tanks each containing 50 L of saltwater. Growth parameters and body composition of the mullets were not significantly affected (P > 0.05) by the dietary treatments. Plasma glucose concentration declined (P < 0.05) when dietary dextrin increased from D250 to D300, but recovered to the previous values (in reference to D150 and D200) when fish were fed with D350. Glycated haemoglobin, plasma proteins, triglycerides and cholesterol showed no significant differences among these treatments. Hepatic glycogen reached a maximum in treatment D250, followed by D350, D200 and D300, with the lowest concentration of liver glycogen found in D150 (P < 0.05). The concentration of liver triglycerides showed an increase (P < 0.05) in treatments D300 and D350 compared with D200. In conclusion, Mugil liza juveniles can be fed diets with high levels of dietary dextrin with no deleterious effects to their growth or plasma biochemistry, hepatic glycogen or triglycerides.     

Effect of high‐dose vitamin C supplementation on growth,tissue ascorbic acid concentrations and physiological response to transportation stress in juvenile silver pomfret,Pampus argenteus

This study investigated the effect of high‐dose vitamin C supplementation on growth, tissue ascorbic acid concentrations and physiological response to transportation stress in juvenile silver pomfret, Pampus argenteus (initial average weight 6.2 ± 0.2 g). Three practical diets were formulated to contain 100 (control), 450 and 800 mg ascorbic acid/kg diet, respectively, supplied as l‐ascorbyl‐2‐polyphosphate. Each diet was fed to triplicate groups of fish in circular tanks (3 m ø, 1.5 m depth) (60 fish/tank) for 9 weeks. Growth did not change significantly with dietary vitamin C levels, although an improvement tendency with an increase in vitamin C supplementation was observed. Ascorbic acid concentrations in the liver and muscle of fish fed diets containing graded levels of vitamin C were positively correlated with dietary levels of this vitamin. Tissue ascorbic acid concentrations significantly increased with increasing vitamin C supplementation. After 9 weeks, the fish were subjected to transportation stress for 4 h to determine the influence of high vitamin C supplementation on the physiological response to this stressor. Serum cortisol, glucose and lactate levels significantly increased in stressed fish. Serum cortisol and glucose concentrations after stress were significantly higher in fish fed the control diet (7.91 μg L^?1 and 0.80 mm , respectively) than in the other groups. However, there were no significant differences in serum cortisol and glucose levels after stress between the 450 and 800 mg kg^?1 diets. No significant change could be found in serum lactate levels after stress among the different treatments. In conclusion, the dietary administration of high doses of vitamin C could reduce stress in silver pomfret and increase the survival of fish under stress conditions.     

Dietary protein requirement for juvenile Chinese sucker (Myxocyprinus asiaticus)

This study was conducted to determine the dietary protein requirement for juvenile Chinese sucker, Myxocyprinus asiaticus. Six fishmeal‐based experimental diets containing various crude protein levels ranging from 300 to 500 g kg^?1 were fed to triplicate groups of 20 fish each (initial weight 13.5 ± 1.1 g) for 56 days at a temperature of 28 ± 1°C (tank size 400 × 45 × 40 cm, linked to a recirculation system). Survival was not affected by dietary protein level (overall survival 71 to 90%). Weight gain (WG) and specific growth rate (SGR) increased with an increasing dietary protein level up to 460 g kg^?1. The feed conversion rate (FCR) generally showed a decline at higher protein levels (from 1.62 in 300 g protein kg^?1 to 1.13 in 500 g protein kg^?1 feed). Protein efficiency ratio (PER) showed gradual improvements with increasing dietary protein up to 460 g kg^?1. A similar trend was found for the protein productive value (PPV). Among the proximate compositions of the fish, crude protein content increased significantly with increasing dietary protein levels. Based on broken‐line regression analysis of SGR against dietary protein levels, the optimal dietary protein requirement for juvenile Chinese sucker was estimated to be close to 465 g kg^?1.     

Antagonistic activity of two potential probiotic bacteria from fish intestines and investigation of their effects on growth performance and immune response in rainbow trout (Oncorhynchus mykiss)

The probiotic activity of two bacterial strains, Lactobacillus casei and Lactobacillus plantarum, isolated from common carp intestines was studied using antagonistic tests in vitro against Yersinia ruckeri. Randomly assigned to triplicate groups were 450 rainbow trout (mean weight, 20 ± 3 g) fed three different diets: a commercial feed, or the same feed incorporated into either 5 × 10⁷ CFU g^?1 of L. casei or L. plantarum. After a 30‐day feeding trial, 30 fish in each group were challenged with Yersinia ruckeri by intraperitoneal injection. Growth parameters were significantly increased in both treatment groups. Immune parameters such as lysozyme activity, alternative complement activity and total immunoglobulin level were significantly higher in the L. casei group than in fish fed the control diet, while no significant differences were revealed between the L. plantarum and control groups. Mortality rates of fish fed L. casei and L. plantarum were lower than in fish fed the control diet after challenging with Y. ruckeri.     

Growth Performance,Hemato-Immunological Responses,and Digestive Enzyme Activities in Silvery-Black Porgy (<Emphasis Type="Italic">Sparidentex hasta</Emphasis>) Fed Dietary Bovine Lactoferrin

An 8-week study was conducted to evaluate three different diets supplemented with bovine lactoferrin (LF) at 0 (control), 800, and 1200 mg LF kg^?1 diet on somatic growth, hemato-immunological parameters, antioxidant status, and digestive enzyme activities in silvery-black porgy (Sparidentex hasta) juveniles. Fish fed the 800 mg LF kg^?1 diet had higher growth performance and feed utilization parameters than the other groups. Hematological and liver antioxidant parameters were not affected by dietary LF supplementation. Fish fed the 800 mg LF kg^?1 diet had higher plasma lysozyme activity values than the other groups. Total protease activity was higher in fish fed LF-supplemented diets than the control group. Results indicated that diet supplemented with 800 mg kg^?1 for 8 weeks enhanced somatic growth performance, lysozyme activity, and proteolytic digestive enzyme activities in S. hasta, as well as improving feed efficiency parameters like the protein efficiency and feed conversion ratios.     

Effect of prebiotic mannan oligosaccharide on hematological and blood serum biochemical parameters of cultured juvenile great sturgeon (Huso huso Linnaeus, 1754)

The nutritional effects of prebiotic mannan oligosaccharide were evaluated using hematological and blood serum biochemical parameters in cultured juvenile great sturgeon (Huso huso). Fish were offered formulated diets containing two levels of prebiotic mannan oligosaccharide (2 and 4 g kg^?1); a basal diet with no prebiotics was used as control. The experiment lasted for 46 days. Blood samples were collected from the caudal veins of 18 apparently healthy fish (average weight 217.77 ± 29.8 g) at the end of the trial. No significant differences were found in the serum enzyme activity levels between treatments (P > 0.05). However, adding mannan oligosaccharide as a supplement to the basal diet resulted in significant differences in lymphocytes and eosinophils between the control and the 2 g kg^?1 treatment (P < 0.05) as well as a significant difference in the creatinine factor in the 2 g kg^?1 mannan oligosaccharide treatment (P < 0.05). The results show that it would be advantageous to add 2 g kg^?1 mannan oligosaccharide to the diets of juvenile great beluga sturgeon (Huso huso).     

Dietary administration of the probiotic,Lactobacillus plantarum,enhanced the growth,innate immune responses,and disease resistance of the grouper Epinephelus coioides

The percent weight gain (PWG) and feed efficiency (FE) of Epinephelus coioides were calculated, and the lactobacilli and total microbiota in the posterior intestines, and non-specific immune parameters of grouper, and its susceptibility to Streptococcus sp. and an iridovirus were determined when the fish were fed diets containing Lactobacillus plantarum at 0 (control), 10⁶, 10⁸, or 10¹⁰ colony-forming units (cfu) kg^?1 for 4 weeks. Results showed that grouper fed a diet containing L. plantarum at the levels of 10⁶, 10⁸, and 10¹⁰ cfu kg^?1 had significantly increased PGW and FE especially at 10⁸ cfu kg^?1 group which were 404.6% and 1.26, respectively. L. plantarum significantly increased in the fish posterior intestines during the L. plantarum feeding period, but decreased rapidly from the intestine within 1 week after changing to the control diet (without L. plantarum). Fish fed a diet containing L. plantarum at 10⁶ and 10⁸ cfu kg^?1 had significantly higher survival rates than those fed the control diet after challenge with Streptococcus sp., as well as those fed 10⁸ cfu kg^?1 after challenge with an iridovirus, causing increases in the survival rates of 23.3%, 20.0%, and 36.7%, respectively, compared to the control group. The alternative complement activity (ACH₅₀) level of fish fed diets containing L. plantarum after 4 weeks was significantly higher than that of fish fed the control diet, and that of the 10⁸ cfu kg^?1 group was significantly higher than those of the 10⁶ and 10¹⁰ cfu kg^?1 groups, which increased by 83.4% compared to the control group. The lysozyme activity and glutathione peroxidase (GPx) activity of fish fed the L. plantarum-containing diets at 10⁸ and 10¹⁰ cfu kg^?1 significantly increased compared to those fed the 10⁶ cfu kg^?1 L. plantarum diet and control diet, and had increased by 76.3% and 136.6%, and 57.1% and 113.3%, respectively, compared to those fed the control diet. The phagocytic activity (PA), phagocytic index (PI), and respiratory bursts of head kidney leucocytes of fish fed 10⁶, 10⁸, and 10¹⁰ cfu kg^?1 L. plantarum diets were significantly higher than those of fish fed the control diet after 4 weeks of feeding, and increased 2.2-, 2.2-, and 2.3-fold; 1.8-, 1.8-, and 2.0-fold; and 1.4-, 1.4-, and 1.4-fold, respectively, compared to the control group. We therefore recommend dietary L. plantarum administration at 10⁸ cfu kg^?1 to promote growth and enhance immunity and resistance against Streptococcus sp. and an iridovirus of E. coioides.     

Dietary arginine requirement of fingerling Indian major carp,Labeo rohita (Hamilton) based on growth,nutrient retention efficiencies,RNA/DNA ratio and body composition

To quantify the optimum dietary arginine requirement of fingerling Indian major carp, Labeo rohita (4.10 ± 0.04 cm; 0.62 ± 0.02 g), an 8‐week growth trial was conducted in eighteen 70‐L indoor circular aqua‐coloured troughs provided with a flow‐through system at 28 ± 1°C. Isonitrogenous (40 g 100 g^?1 crude protein) and isocaloric (4.28 kcal g^?1 gross energy) amino acid test diets containing casein and gelatin as intact protein sources with graded levels of arginine (0.5, 0.75, 1.0, 1.25, 1.50 and 1.75 g 100 g^?1 dry diet) were fed to triplicate groups of fish to apparent satiation at 07:00, 12:00 and 17:30 hours. Growth performance of fish fed the above diets was evaluated on the basis of absolute weight gain (AWG), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), protein retention efficiency (PRE) and energy retention efficiency (ERE). Maximum AWG (2.61), SGR (2.80), best FCR (1.35), highest PER (1.85), PRE (37%) and ERE (76%) were recorded at 1.25 g 100 g^?1 dietary arginine. Maximum body protein (18.88 g 100 g^?1) and RNA/DNA ratio (5.20) were also obtained in a 1.25 g 100 g^?1 arginine dry diet. Except for the reduced growth performance in fish fed arginine‐deficient diets, no other deficiency signs were apparent. Based on the broken‐line and second‐degree polynomial regression analysis of the AWG, SGR, FCR, PER, PRE and ERE data, the optimum arginine requirement for fingerling Labeo rohita was found to be in the range of 1.22–1.39 g 100 g^?1 of the dry diet, corresponding to 3.05–3.47 g 100 g^?1 of dietary protein.     

Effect of dietary L‐malic acid supplementation on growth,feed utilization and digestive function of juvenile GIFT tilapia Oreochromis niloticus (Linnaeus, 1758)

Two feeding trials (FTs) were conducted in 2013 and 2014, respectively, to determine the optimal L‐malic acid (LMA) level for juvenile GIFT (Genetically Improved Farmed Tilapia) Oreochromis niloticus. Except for the LMA level, the FT1 and FT2 had a similar diet formulation. In FT1, LMA was included at 0 (basal diet), 1, 4, 8, 16 and 32 g kg^?1, respectively. After 20 weeks, daily weight gain and feed conversion ratio were improved but not differentiated with 1–8 g kg^?1 LMA. Further increasing the LMA supply initially decreased the feed intake (16 g kg^?1), and then decreased both feed intake and feed utilization (32 g kg^?1), thus impairing the fish growth. FT2 was subsequently conducted with a smaller LMA range (0, 0.5, 1, 2, 4 and 8 g kg^?1, respectively) but was unfortunately terminated at the end of 8 weeks because 20% of the fish were badly injured during weighing. Unexpectedly, growth and feed utilization were still improved but not differentiated with 0.5–8 g kg^?1 LMA. In FT2, beneficial effects of LMA inclusion on the digestive function (pepsin, foregut amylase and foregut lipase), the activities of serum lysozyme and hepatic superoxide dismutase, and liver lipid peroxidation (malondialdehyde concentration) were found. Taking the results of FT1 and FT2 together, it could be concluded that dietary LMA supplementation at low concentrations (0.5–8 g kg^?1) could improve growth and feed utilization, but excess LMA (≥16 g kg^?1) might compromise feed intake and/or feed utilization, thus impairing fish growth. To reduce feed costs in commercial practice, 0.5 g kg^?1 LMA is recommended in the feed of juvenile GIFT tilapia based on the results of this study.