Effect of supplemental taurine on juvenile channel catfish Ictalurus punctatus growth performance

Juvenile channel catfish (5.6 g/fish) were fed a basal diet that contained major protein (soybean meal, cottonseed meal) and energy (ground corn grain, wheat middlings) ingredients that were derived from plant sources. The basal diet was supplemented with three levels of crystalline taurine to provide 1, 2 and 5 g/kg taurine. In addition, a fifth diet that contained 80 g/kg menhaden fishmeal formulated with the same plant‐source ingredients was included as the positive control diet. Fish were fed the five diets once daily for 12 weeks. Weight gain was highest in catfish fed taurine at 2 g/kg (47.8 g/fish) compared to catfish fed the control basal diet (40.8 g/fish) and 80 g/kg fishmeal diet (41.1 g/fish) (p < .05). Among the taurine‐supplemented diets, weight gain was lowest in catfish fed taurine at 5 g/kg. Feed conversion ratio (FCR) was significantly improved in fish fed diets supplemented with taurine at 2 g/kg compared to all other treatments (p < .01). Survival during the growth study ranged from 98.0 to 99.0% (p > .05) for all treatments. The results suggest taurine supplementation to juvenile channel catfish may improve weight gain and FCR.     

Fishmeal levels can be successfully reduced in white shrimp (Litopenaeus vannamei) if supplemented with DL‐Methionine (DL‐Met) or DL‐Methionyl‐DL‐Methionine (Met‐Met)

The main objective of this study was to evaluate the effect of methionine supplementation when reducing fishmeal levels in diets for white shrimp (Litopenaeus vannamei). Tested diets consisted of a positive control with 260 g/kg fishmeal (D1), two negative controls with 100 g/kg fishmeal and no amino acid (AA) supplementation (D2) or supplemented with lysine but not methionine (D3), and four additional diets with 100g/kg fishmeal supplemented with increasing levels of DL‐Met (1.0, 2.0 or 3.0 g/kg) (D4, D5, D6) or Met‐Met (1.0 g/kg) (D7). Each diet was fed to four groups of 30 shrimp for 8 weeks at a daily rate of 70 g/kg body weight. Reduction in fishmeal from 260 g/kg down to 100 g/kg did not significantly affect survival rate, feed conversion ratio (FCR), protein efficiency ratio (PER) or protein retention efficiency (PR%) of white shrimp. However, growth performance (final body weight, FBW; weight gain, WG; specific growth rate, SGR) was reduced when dietary fishmeal level was reduced from 260 g/kg (D1) to 100 g/kg without methionine supplementation (D2). The growth performance (FBW, WG and SGR) of shrimp was significantly increased by supplementation of the 100 g/kg fishmeal diet with increasing levels of DL‐Met (p < .05). Same performance as positive control (D1) was achieved with diets containing 100 g/kg fishmeal and supplemented with 3.0 g/kg DL‐Met or 1.0 g/kg Met‐Met. The highest values of growth performance (FBW, WG and SGR) were found in shrimp fed D6 and D7 diets, which were significantly higher than those of shrimp fed D2 and D3 diets (p < .05) but without statistical differences with shrimp fed D1, D4 and D5 diets (p > .05). The highest values of whole‐body and muscle protein contents were found in shrimp fed D1 diet, which were significantly higher than those of shrimp fed all other diets (p < .05). The highest value of intestinal tract proteolytic enzyme activity was found in shrimp fed Met‐Met‐supplemented diet (D7) and followed by the positive control diet (D1) and 3 g/kg DL‐Met‐supplemented diet (D6) (p < .05). The highest values of apparent digestibility coefficients (ADCs) of dry matter and crude protein were found in Met‐Met‐supplemented diet (D7) and followed by the positive control diet (D1) (p < .05). Shrimp fed the D1 diet showed the highest value of total essential amino acid (EAA) and was significantly higher than shrimp fed D2–D3 (p < .05) but without significant difference with shrimp fed D4–D7 (p > .05). In conclusion, results showed that same performance can be achieved with diets containing 260 or 100 g/kg fishmeal supplemented with 3.0 g/kg DL‐Met or 1.0 g/kg Met‐Met. Moreover, supplementation of limiting methionine in low‐fishmeal diets seems to improve the digestive proteolytic activity, improving digestibility of dry matter and protein, and eventually to promote growth of juvenile white shrimp in fishmeal reduction diets.     

Effects of dietary coated protease on growth performance,feed utilization,nutrient apparent digestibility,intestinal and hepatopancreas structure in juvenile Gibel carp (Carassius auratus gibelio)

This study was conducted to investigate the effects of dietary protease on growth performance, feed utilization, whole‐body proximate composition, nutrient digestibility, intestinal and hepatopancreas structure of juvenile Gibel carp, Carassius auratus gibelio (mean weight 8.08 ± 0.18 g). Six diets were prepared, including a positive control diet (dietary protein 350 g/kg, PC), one negative control diet (dietary protein 33 g/kg, NC) and four protease supplementations diets, which were 75, 150, 300 and 600 mg/kg protease NC diet. After 12 weeks of diet feeding in indoor recycle aquarium tanks, no significant difference (p > .05) was found on growth performance between fish fed diet with 75–600 mg/kg protease and the PC group. Compared with the fish fed the NC diet, the specific growth rate of fish fed 300 mg/kg protease increased significantly (p < .05), as well as protein efficiency ratios (p < .05), while feed conversion was the opposite (p < .05). The nutrient digestibility of crude protein and lipid was higher (p < .05) in fish fed 150 mg/kg protease diet than the PC diet. Whole‐body proximate composition of fish was not affected (p > .05) by the dietary treatment. Serum alkaline phosphatase and albumin were significantly affected by dietary protease (p < .05), while the content of total protein, glucose, triglyceride, total cholesterol, aspartate aminotransferase and alanine aminotransferase activities in serum was not affected (p > .05). Foregut muscular thickness was thinner (p < .05), when the fish fed diets supplementation of protease in 150 or 600 mg/kg diet than the NC diet. Protease activities in hepatopancreas and foregut were higher (p < .05), in the fish fed 150 or 300 mg/kg protease diet than the fish fed the PC diet, but those in the mid‐ and hindgut were not significantly affected (p > .05) by the dietary treatments. Based on the regression analysis of weight gain rate, the optimal dietary inclusion level of protease was 400 mg/kg in the diet for juvenile Carassius auratus gibelio.     

Optimum level of dietary monocalcium phosphate determined based on optimal growth and vertebrae phosphate content of juvenile Ussuri catfish,Pseudobagrus ussuriensis

Two experiments were conducted to determine the optimum level of dietary available phosphorus from monocalcium phosphate for juvenile Ussuri catfish Pseudobagrus ussuriensis. Experiment 1 was conducted to estimate phosphorus digestibility from monocalcium phosphate for juvenile Ussuri catfish. The apparent digestibility coefficient of phosphorus from monocalcium phosphate was 86.3%. In the experiment 2, triplicate groups of juvenile Ussuri catfish were fed diets containing graded levels of monocalcium phosphate (MCP: 0 g/kg, 8.2 g/kg, 16.4 g/kg, 24.6 g/kg, 32.8 g/kg and 41.0 g/kg) for 8 weeks. Fish fed the diet containing 16.4 g/kg MCP with available phosphorus of 4.8 g/kg showed the best weight gain (171.5%), feed conversion ratio (1.08) and protein efficiency ratio (2.06). No significant difference was observed in fish survival among the treatments. The best result in terms of phosphorus retention efficiency (46.10%) was observed in fish fed the diet containing 8.2 g/kg MCP with available phosphorus of 3.0 g/kg, which was not different (p > .05) from those fed the diet containing up to 24.6 g/kg MCP, and the highest vertebrae phosphorus content (58.2 g/kg) was observed in fish fed the diet containing 24.6 g/kg MCP with available P of 6.6 g/kg. The whole‐body lipid and protein, as well as phosphorus contents, were significantly affected by dietary available phosphorus (p < .05). Viscerosomatic index (VSI) and condition factor (CF) were inversely correlated with dietary phosphorus levels (p < .05). Quadratic regression analysis based on specific growth rate (SGR) against dietary available phosphorus levels indicated that the optimum available phosphorus requirement for the maximal growth of juvenile Ussuri catfish was 5.9 g/kg, and broken‐line analysis based on vertebrae phosphorus content against dietary available phosphorus levels indicated that a dietary level of 6.0 g/kg available phosphorus will provide optimum vertebrae phosphorus content.     

Dietary available phosphorus requirement for juvenile gibel carp (Carassius auratus gibelio var. CASIII)

A 57‐day growth experiment was conducted with juvenile gibel carp (13.48 ± 0.10 g) in a flow‐through system to study the effect of dietary phosphorus on growth performance, body composition, nutrition utilization, phosphorus loading and enzymes activities. Seven semipurifed diets were formulated to contain 0.07 (the basal), 2.27, 5.32, 8.10, 12.06, 15.24 and 19.48 g available phosphorus/kg diet. The results showed that specific growth rate, body length and feed efficiency significantly increased in the fish fed diets containing 0.07 to 15.24 g available P/kg diet (p < .05). Ash and P content increased in fish fed diets containing 0.07–12.06 P g/kg (p < .05) and then levelled off, while moisture, crude protein and lipid had no significant difference (p > .05). The protein retention efficiency increased in the fish fed with diets 0.07–5.32 g/kg P (p < .05) and then reached a plateau. The P content in faeces was higher in fish fed diets containing 15.24 and 19.48 g available P/kg. Total P concentration in tank water increased in fish fed 0.07–12.06 g available P per kg diet (p < .05). The plasma P was higher in the fish fed with 15.24 g available P/kg diet (p < .05), triglycerides was lower in the fish fed diet containing 15.24 and 19.48 g available P/kg (p < .05), no significant differences were observed in plasma Ca, plasma glucose and calcitonin (p > .05). Based on SGR, whole body P content and FE, dietary available P requirement for juvenile gibel carp were 13.37, 13.97 g/kg and 15.06 respectively.     

Partial substitution of soybean meal with fermented soybean residue in diets for juvenile largemouth bass,Micropterus salmoides

A feeding trial was conducted to investigate the effects of partial replacement of soybean meal (SBM) with fermented soybean residue (FSR) on growth performance, body composition and plasma biochemical parameters of largemouth bass, Micropterus salmoides. Soybean residue was fermented with a mixture of microorganisms (Bacillus subtilis, Lactobacillus spp. and Molasses yeast) using the solid‐state fermentation. Four isonitrogenous (crude protein 430 g/kg) and isoenergetic (gross energy 18 MJ/kg) diets were formulated by replacing 0 (the control), 20, 40 and 60g/kg of protein from SBM with FSR (FSR0, FSR20, FSR40 and FSR60, respectively). Each diet was fed to four replicate groups of fish (initial body weight: 17.1 ± 0.19 g) for 12 weeks. Results showed that dietary FSR substitution significantly improved growth of juvenile largemouth bass. The weight gain, specific growth rate and protein efficiency ratio were all significantly improved by dietary FSR level up to 40g/kg substitution level (p < .05) and then levelled off beyond this level. Fish fed the diet with 40g/kg and 60g/kg protein from FSR had lower feed conversion ratio than the control group (p < .05). The hepatosomatic index, viscera ratio and liver lipid content significantly decreased with increasing dietary FSR level. Total protein content, superoxide dismutase and alkaline phosphates activities in plasma were lower in fish fed the control diet (p < .05) than the other groups. However, both alanine aminotransferase and aspartate transaminase were higher in fish fed the control diet (p < .05) compared to the other treatments. The plasma catalase activity significantly increased with increasing dietary FSR level, while plasma triglyceride, total cholesterol, glucose and malondialdehyde contents significantly reduced. No significant difference was observed in the glutathione peroxidase activity among dietary treatments. These findings demonstrated that replacing dietary SBM with FSR has beneficial effects on growth of M. salmoides, and the best growth performance was obtained at 40g/kg replacement for SBM protein. In addition, there is a great potential to apply FSR to improve lipid metabolism and antioxidant capacity of M. salmoides.     

Effects of Chinese herbal medicines mixture on growth performance digestive enzyme activity immune response of juvenile Japanese seabass,Lateolabrax japonicus

A single factorial experiment was conducted to investigate the effects of Chinese herbal medicines mixture (CHMM) on growth performance, digestive enzyme activity and immune response of Japanese seabass, Lateolabrax japonicus (initial weight 5.01 ± 0.32 g). The fish were fed diets containing six levels of CHMM (0, 4, 8, 12, 16 and 20 g/kg) for 4 weeks. The results showed that the weight gain rate and specific growth rate (SGR) enhanced significantly in fish fed diet containing 8 g/kg CHMM (p < .05), while the feed conversion ratio (FCR) in the 4 and 8 g/kg CHMM groups reduced significantly compared with the control (p < .05). The body crude protein levels in 8 and 16 g/kg groups were significantly higher than the control (p < .05). The pepsin, amylase and lipase activities elevated significantly in the stomach of fish fed 8 g/kg CHMM, while the erepsin and lipase in the intestine of fish in 12 and 16 g/kg groups were higher significantly than the control (p < .05). The lysozyme, alkaline phosphatase, acid phosphatase (ACP), total antioxidative capacity activities in serum of fish fed 12 g/kg CHMM were higher significantly than those in the control (p < .05), while the total superoxide dismutase (SOD), total antioxidative capacity, catalase, alkaline phosphatase (AKP) and ACP activities in hepatopancreas of fish in 12 g/kg group were all significantly higher than those in the control (p < .05). Regression analysis showed that the relationships between dietary CHMM levels and either FCR, SGR, erepsin, pepsin or lysozyme activities were best expressed by quadratic or cubic regression equations, and the optimal inclusion levels are 11.4, 10.7, 10.7, 8.4 and 10.5 g/kg for maximum FCR, SGR, erepsin, pepsin and lysozyme activities, respectively. Under the present experimental condition, the optimal supplementary level of CHMM in the diet of Japanese seabass is 8–12 g/kg.     

Dietary pantothenic acid requirement of fingerling Channa punctatus (Bloch) based on growth,feed conversion,liver pantothenic acid concentration and carcass composition

A 16‐week feeding trial was conducted to determine the dietary pantothenic acid requirement of fingerling Channa punctatus. Six casein–gelatin‐based diets (450 g/kg CP; 18.39 kJ/g GE) with graded levels of pantothenic acid (0, 10, 20, 30, 40 and 50 mg/kg diet) were fed to triplicate groups of fish (6.2 ± 0.71 cm; 4.26 ± 0.37 g) near to apparent satiation. The growth evaluation in terms of absolute weight gain (AWG), feed conversion ratio (FCR) and protein retention efficiency (PRE) indicated the best performance (p < .05) in fish fed diet containing 30 mg/kg pantothenic acid. Highest haemoglobin, haematocrit and RBCs counts were also obtained in fish fed diet with 30 mg/kg pantothenic acid. Mean cell haemoglobin and mean cell volume were found to be lowest in fish fed pantothenic acid‐free diet indicating the anaemia in this group of fish. Superoxidase dismutase and catalase activities of liver tissue were found to improve (p < .05) with the increasing levels of dietary pantothenic acid from 0 to 30 mg/kg. However, liver pantothenic acid concentration responded positively with the increasing levels of pantothenic acid up to 40 mg/kg diet and then stagnation in liver pantothenic acid concentration with the further inclusion of pantothenic acid was recorded. Second‐degree polynomial regression analysis of AWG, FCR and PRE exhibited the pantothenic acid requirement at 36.4, 32.8 and 34.7 mg/kg diet, respectively. Data generated during this study would be useful in formulating pantothenic acid‐balanced commercial feeds for the intensive culture of this fish.     

Replacement of fish oil with a DHA‐rich Schizochytrium meal on growth performance,activities of digestive enzyme and fatty acid profile of Pacific white shrimp (Litopenaeus vannamei) larvae

This trial was conducted to evaluate the effects of replacing dietary fish oil with Schizochytrium meal for Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Six test microdiets were formulated using Schizochytrium meal to replace 0 g/kg, 250 g/kg, 500 g/kg, 750 g/kg, 1000 g/kg or 1500 g/kg fish oil DHA. No significant differences were observed in survival, growth, final body length and activities of digestive enzyme among shrimp fed different diets (p > .05). No significant differences were observed in C20:5n‐3 (EPA) in muscle samples (p > .05). C18:3n‐3 and C20:4n‐6 in muscle increased as Schizochytrium meal replacement level increased (p < .05). No significant differences were observed in C22:6n‐3 (DHA) and n‐3 fatty acids among shrimp fed diets that algae meal replaced 0 g/kg ‐ 1000 g/kg of fish oil. Shrimp fed diet R150 had higher DHA content than other groups and had higher n‐3 fatty acids than that of shrimp fed diets R50, R75 and R100 (p < .05). C18:2n‐6, PUFA and n‐6 fatty acids in muscle increased, while n‐3/n‐6 ratio decreased with increasing algae meal replacement level from 0 g/kg to 1000 g/kg (p < .05). In conclusion, Schizochytrium meal could replace 1500 g/kg fish oil DHA in the microdiets without negatively affecting shrimp larvae survival, growth and activities of digestive enzyme.     

Effects of dietary chlorogenic acid on growth,flesh quality and serum biochemical indices of grass carp (Ctenopharyngodon idella)

The study was to investigate effects of dietary chlorogenic acid (CGA) on growth performance, flesh quality and serum biochemical indices of grass carp (95.1 ± 0.3 g) (Ctenopharyngodon idella) fed seven different diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g kg^–1) and CGA‐supplemented diets containing 100, 200, 400, 600 and 800 mg/kg CGA. Contents of collagen and alkaline‐insoluble collagen in muscle and skin were significantly increased by dietary CGA and EU (p < .05). Total essential amino acids (TEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet or 400, 600 and 800 mg/kg CGA diet were significantly higher than those of fish fed control diet and 100 and 200 mg/kg CGA diet (p < .05). Fish fed 200–800 mg/kg CGA showed significantly lower muscle crude lipid content than EU, control and 100 mg/kg CGA groups (p < .05). Fish fed CGA‐supplemented diets (100–800 mg/kg) had significantly higher muscle fibre density and lower muscle fibre diameter than control group (p < .05). In conclusion, supplementation of CGA improved flesh quality of grass carp, and supplemental level of CGA for improving flesh quality and growth was estimated to be 400 mg/kg diet.     

Effect of dietary leucine on growth performance,hemolymph and hepatopancreas enzyme activities of swimming crab,Portunus trituberculatus

An 8‐week feeding trial was conducted to determine the dietary leucine requirement for juvenile swimming crabs reared in cement pools. Six isonitrogenous and isolipidic practical diets (430 g/kg crude protein and 70 g/kg crude lipid) were formulated to contain graded leucine levels which ranged from 16.7 to 26.7 g/kg (dry weight). Each diet was randomly assigned to triplicate groups of 60 juvenile swimming crabs (initial average weight 3.75 ± 0.12 g) that were stocked in rectangle plastic baskets. The results of the present study indicated that dietary leucine levels significantly influenced weight gain (WG) and specific growth ratio (SGR) (p < .05), crab fed the diet containing 22.7 g/kg leucine had significantly higher WG and SGR than those fed the other diets. Feed efficiency and protein efficiency ratio were not significantly affected by the dietary leucine levels (p > .05). Total protein, cholesterol, triglyceride and glucose in serum were significantly affected by the dietary leucine levels. Aspartate aminotransferase (AST) and alanine aminotransferase activities in hemolymph, AST and superoxide dismutase activities in hepatopancreas were significantly affected by dietary leucine levels; moreover, crab fed the 16.7 g/kg leucine diet had higher malondialdehyde in hemolymph and hepatopancreas than those fed the other diets. Crab fed the diet containing 24.9 g/kg leucine had higher phenoloxidase activity in hemolymph than those fed the other diets. Based on two‐slope broken‐line model of SGR against dietary leucine levels, the optimal dietary leucine requirement for growth was estimated to be 22.1 g/kg of the dry diet (corresponding to 51.4 g/kg of dietary protein on a dry weight basis). In summary, findings of this study indicated that dietary leucine could improve growth performance and antioxidant status.     

The effects of dietary inulin and Jerusalem artichoke (Helianthus tuberosus) tuber on the growth performance,haematological, blood chemical and immune parameters of Nile tilapia (Oreochromis niloticus) fingerlings

This study investigated the effects of dietary inulin or Jerusalem artichoke (JA) on the growth performance, haematological, blood chemical and immune parameters of Nile tilapia fingerlings. Five treatment diets were designed to incorporate inulin at 0 (basal diet), 2.5 and 5.0 g/kg and JA at 5.0 and 10.0 g/kg. Two basal diets including fish meal and formulated experimental feed were used for fry and fingerling growing periods, respectively. During the fry growing period, larvae were fed treatment diets for 4 weeks. There were no significant differences in growth performance or survival rate. Fingerlings were then nursed with the formulated experimental diets from weeks 5 to 12. Fingerlings fed on inulin at 5.0 g/kg or JA at either level had better growth performance and survival rate than that fed on the basal diets. There were no significant differences in body composition. Dietary prebiotic inulin and JA increased red blood cell number (p < .05). Among the five blood chemistry parameters examined, both inulin at 5.0 g kg and JA (5.0 and 10.0 g/kg) increased blood protein (p < .05). Dietary inulin at 5.0 g/kg and JA at 5.0 and 10.0 g/kg increased total immunoglobulin and lysozyme activity (p < .05). Both inulin and JA inclusion diets increased alternative complement activity (p < .05). Taken together, dietary inulin at 5 g/kg and JA at 5.0 and 10.0 g/kg had beneficial effects on the growth performance, survival rate and immune of Nile tilapia fingerlings.     

A Comparison between dietary effects of Cuminum cyminum essential oil and Cuminum cyminum essential oil,loaded with iron nanoparticles,on growth performance,immunity and antioxidant indicators of white leg shrimp (Litopenaeus vannamei)

This study evaluates the effect of dietary cumin essential oil's (CEO) and cumin essential oil's loaded iron nanoparticles (CEO‐loaded NPs) on growth performance, haematological parameters and antioxidant status of white leg shrimp. Shrimps with the initial weight of 3.38 ± 0.014 g were allocated into 15 fibreglass tanks (300 L, 60 shrimps per tank) and were fed with five experimental diets containing 0 g/kg CEO (the control diet), 5 g/kg CEO, 10 g/kg CEO, 5 g/kg CEO‐NPs and 10 g/kg CEO‐NPs for 56 days. After 56 days of culture, the shrimps fed with CEO and CEO‐loaded NPs supplemented diets showed a more significant increase in growth performance (p < .05) than in the control diet. Total haemocyte count (THC) value, large‐granule cells (LGC), hyaline cells (HC)%, superoxide dismutase (SOD) and Alkaline phosphatase (AKP) activity were significantly higher (p < .05) in the shrimps fed with CEO and CEO‐loaded NPs supplemented diets than the shrimps fed with the control diet. Glutathione peroxidase (GPX) enzyme activities along with the glucose and cholesterol concentrations significantly decreased in the shrimps fed with the CEO and CEO‐loaded NPs supplemented diets more than those fed with the control diet. The results suggest that the dietary CEO‐loaded NPs can improve the growth performance, the health status and the antioxidant capacity of L. vannamei.     

Dietary supplementation of red alga Pyropia spheroplasts on growth,feed utilization and body composition of sea cucumber,Apostichopus japonicus (Selenka)

A feeding experiment was conducted in a closed recirculating system to evaluate the effects of freeze‐dried spheroplasts prepared from Pyropia yezoensis (Ueda) on feed intake, growth and biochemical composition of sea cucumber, Apostichopus japonicus (Selenka). Pyropea spheroplasts (PS) were prepared through enzymatic treatment to break down the complex mixture of polysaccharides cell walls that might be easier for growth energy partitioning. Sea cucumbers were fed‐formulated diets with 10 (Diet 1), 30 (Diet 2) and 50 g/kg (Diet 3) inclusion level of PS. A diet without PS was used as a control (Diet 4). The experiment was conducted for 6 weeks maintaining water temperature 15 ± 1°C, photoperiod 18:06 hours (D:L). Feed was supplied ad‐libitum at 16.00 h once in a day, and the remaining feed and faeces were removed in the next day. Results showed that the highest growth was observed in the 50 g/kg PS diet compared to other treatments. Total weight gain, mean weight gain, net yield, protein efficiency ratio (PER) and protein gain (%) were significantly higher in the 50 g/kg PS diet (p < .05). A significantly higher percentage of energy was allocated for growth in the 50 g/kg PS diet. The highest specific growth rate and feed conversion efficiency (p < .05) were observed in the higher percentage of PS diet. Both the growth performance and biochemical analysis showed that superior growth was observed with increasing levels of PS in the diet. We infer that PS can be used as a new, cheaper feed ingredient in the formulated diet of A. japonicus.     

Effects of garlic powder on feeding attraction activity,growth and digestive enzyme activities of Japanese seabass,Lateolabrax japonicus

The study was to investigate the effects of garlic (Allium sativum) powder on feeding attraction activity, growth performance and digestive enzymes of juvenile Japanese seabass, Lateolabrax japonicus (initial weight: 29.82 ± 0.24 g). Six concentration gradients (0, 5, 10, 15, 20 and 25 g/kg diets) were formulated for luring and feeding experiment. The results showed a clear attractive trend of garlic powder for L. japonicus. A 28‐day feeding experiment indicated garlic could reduce the feed conversion ratio (FCR) (p < .05). The content of the body crude lipid was significantly increased at 10–15 g/kg diet (p < .05). Digestive enzyme activities including trypsin, amylase (AMS) and lipase (LPS) in the intestine were the highest at 10 g/kg diet (p < .05). Overall, garlic powder provides a promising and effective method for Japanese seabass healthy culture by improving fish growth and digestive ability. The results of this research suggested the additive suitable dosage of garlic powder was about 10 g/kg diet.     

Growth,enzymatic glutathione peroxidase activity and biochemical status of juvenile barramundi (Lates calcarifer) fed dietary fermented lupin meal supplemented with organic selenium

To investigate the effects of high level of lupin meal (LM) supplemented with organic selenium (OS) on the growth and blood biochemistry of barramundi (Lates calcarifer), four isocaloric and isonitrogenous diets were prepared, containing either non‐fermented or fermented LM, and either supplemented with 2 mg OS/kg (LM, LM_OS, FLM and FLM_OS), or not. A fishmeal (FM)‐based diet formulated for juvenile barramundi was used as a control diet. Fish (initial mean weight of 5.88 g) were triplicated and fed the test diets for 75 days. The findings demonstrated that growth performance of fish fed with the FLM and FLM_OS diets were similar to fish fed with the FM diet (p > .05). The antioxidant glutathione peroxidase (GPx) activity, and haemoglobin (Hb) of fish fed with the FLM_OS diet were significantly higher than that of FM‐fed fish (p < .05). Plasma alanine aminotransferase (ALT) activity was significantly increased in fish fed with non‐fermented diets (LM and LM_OS) than in those fed with fermented LM diets (FLM and FLM_OS) (p < .05). However, there were no significant differences in ALT activity among LM_OS, FLM, FLM_OS and FM diets. There was an interaction between the LM and OS on plasma CK activity; the CK of fish fed with diets supplemented with OS was higher in non‐fermented LM diets but lower in fermented LM diets (p < .05). This study suggests that fermented LM have an obvious potential to substantially replace 75% FM protein in the diets of barramundi.     

Effects of dietary geniposidic acid on growth performance,flesh quality and collagen gene expression of grass carp,Ctenopharyngodon idella

This study was conducted to investigate the effects of dietary geniposidic acid (GA) on growth performance, flesh quality and collagen gene expression of grass carp (Ctenopharyngodon idella). The fish with an initial body weight of 47.1 ± 0.8 g were fed one of the seven diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g/kg) and GA‐supplemented diets (200, 400, 600, 800 and 1,000 mg/kg GA) for 75 days. The growth performance and muscle proximate composition showed no difference among groups (p > .05). Dietary GA (200–1,000 mg/kg) increased the contents of total collagen and alkaline‐insoluble collagen in skin (p < .05), and high supplementation of GA (600–1,000 mg/kg GA) and EU increased the contents of total collagen, alkaline‐insoluble collagen and total amino acids (p < .05), but reduced the lipid level in muscle (p < .05). In collagen gene expression, EU and 200–1,000 mg/kg GA increased COL1A1 expression in muscle and skin (p < .05), but the expression of COL1A2 was increased only by high supplementation of GA (1,000 mg/kg, or 800–1,000 mg/kg) (p < .05). In conclusion, dietary GA improved the flesh quality of grass carp, and the supplementation level was estimated to be 600 mg/kg diet.     

Dietary manganese requirement of juvenile hybrid grouper,Epinephelus lanceolatus × E. fuscoguttatus

An 8‐week feeding trial was conducted to estimate the optimum dietary manganese (Mn) requirement for juvenile hybrid grouper, Epinephelus lanceolatus × E. fuscoguttatus. The basal diet was formulated to contain 520 g/kg crude protein from casein and fishmeal. Manganese methionine was added to the basal diet at 0 (control group), 2.5, 5, 10, 20 and 40 mg Mn/kg diet providing 7.48, 10.34, 13.76, 19.72, 31.00 and 53.91 mg Mn/kg diet, respectively. Each diet was randomly fed to triplicate groups of juveniles, and each tank was stocked with 20 fish (initial weight, 60.06 ± 0.68 g). The manganese content in rearing water was monitored and kept below 0.01 mg/L. Results showed that the weight gain ratio (WGR), protein efficiency ratio (PER), specific growth rate (SGR), Mn contents in whole body, liver and vertebra, and activities of hepatic Mn superoxide dismutase (Mn‐SOD), total SOD (T‐SOD) and glutathione peroxidase (GSH‐PX) were significantly improved by dietary Mn supplementation (p < .05). However, dietary Mn did not affect arginase (DArg) activity. The highest feed conversion ratio (FCR) was observed in fish fed the basal diet (p < .05). No significant differences were found on the Cu and Zn contents in whole body by supplementing dietary Mn. Supplemented Mn in diets had significantly effect on liver and vertebral trace element deposition (p < .05). Fish fed the basal diet had the highest Fe and Zn contents in vertebra (p < .05). There were no significant differences on hepatic pyruvate decarboxylase (PDC) activity with supplemented Mn levels below 13.76 mg/kg. As biomarker of oxidative stress, malondialdehyde (MDA) content in liver was significantly higher in fish fed the basal diet (p < .05). Using the broken‐line models based on SGR, dietary Mn requirement of the juvenile hybrid grouper was estimated to be 12.70 mg/kg diet.     

Dietary combination of pawpaw seed and onion peel powder: Impact on growth,haematology, biochemical and antioxidant status of Clarias gariepinus

A feeding trial was conducted to evaluate the effect of pawpaw–onion powder (POP) mixture on the growth, and haemato‐biochemical and antioxidant responses of Clarias gariepinus (4.02 ± 0.01g/fish) for 60 days. Five trial diets were formulated as control (without POP or antimicrobial growth promoter (AGP)), AGP (basal diet + 10ml AGP/kg diet), POP 2.5 (basal diet + 2.5g POP/kg diet), POP 5.0 (basal diet + 5.0g POP/kg diet) and POP 10 (basal diet + 10g POP/kg diet). Two hundred and twenty‐five fish were equally distributed into five groups in triplicate and fed twice daily. The results indicate that AGP or POP supplementation exerted no effects on the growth and blood profile among the various groups, but a significantly higher lymphocyte count was observed in POP 10g/kg. The highest whole‐body protein and lipid contents were noticed in fish fed the control diet (p < .05), whereas POP 5.0g/kg group recorded the highest hepatosomatic value. Furthermore, the cholesterol level was found to be lower in the AGP‐ and POP‐fed fish compared with the higher level recorded in the control. The glucose concentration and superoxide dismutase enzyme activity were found to be higher in POP 2.5‐fed fish, whereas POP 10‐fed fish showed higher catalase activities compared with other groups (p < .05). Based on the result obtained, this study showed that dietary POP had no significant impact on the growth performance but has direct effects on the whole‐body lipid content, lymphocyte count, cholesterol level, alanine aminotransferase, alkaline phosphatase and antioxidant response of Clarias gariepinus.     

Dietary protease modulates nutrient retention efficiency and hepatopancreatic protease activity in juvenile Chinese mitten crab Eriocheir sinensis

An 8‐week growth trial was conducted with juvenile Chinese mitten crab fed a high fishmeal (FM) diet (PC), a low FM diet (NC) and three other diets (NC125, NC150 and NC175) supplemented with 125, 150 and 175 mg/kg of a dietary protease. In the NC diets, a portion of FM (from PC diet) was replaced by a combination of plant proteins. All diets were isoproteic (404 ± 3 g/kg) and isoenergetic (18.6 ± 0.2 kJ/g). No differences were observed among treatments in most parameters except protein (PRE, %) and lipid (LRE, %) retention efficiencies, where LRE was the highest (37.9%) in NC175 followed by the PC. A linear regression demonstrated significant effects of protease on hepatopancreatic trypsin activity (HPRO, p = .001), and PRE (p = .05) and LRE (p = .014) but not on energy retention efficiency (ERE). Dietary protease level was positively correlated with HPRO and nutrient retention efficiency (p < .05). On the other hand, the specific growth rate (SGR) was positively correlated with portein deposition (PD), lipid deposition (LP) and recovered energy (RE) and negatively correlated with survival (p < .05). This study is first to demonstrate that mainly nutrient retention efficiencies are modulated by specific dietary enzymes in animals.