Effect of dietary microbial phytase supplementation on growth and nutrient digestibility of Pangasius pangasius (Hamilton) fingerlings

A feeding trial was conducted for 60 days to study the effects of exogenous microbial phytase supplementation on the growth and nutrient digestibility of Pangasius pangasius fingerlings. Eight isocaloric and isoprotein experimental diets (35.67% crude protein and 3870 kcal kg^?1) were prepared with graded levels of phytase, e.g., 0 (T₁), 150 (T₂), 250 (T₃), 350 (T₄), 500 (T₅), 1000 (T₆) and 2000 (T₇) FTU (phytase units) kg^?1. Three hundred and fifteen fingerlings of P. pangasius (1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. Maximum weight gain (350.72%), specific growth rate (2.51%), protein efficiency ratio (2.1), apparent net protein utilization (27.85%), energy retention value (88.47%) and feed conversion efficiency were observed in T₅ group supplemented with 500 FTU phytase kg^?1 diet. Apparent dry matter and protein digestibility in phytase‐supplemented groups were significantly (P<0.01) higher at a minimum supplement of 500 FTU kg^?1 or higher. Liver alkaline phosphatase activity increased significantly in treatment groups. Supplementation at 500 FTU kg^?1 of phytase is optimum in the diet of P. pangasius fingerlings.     

Stocking density effects on growth and production of the threatened silurid catfish,Mystus cavasius (Hamilton) fingerlings in nursery ponds

The fingerling‐rearing experiment of the threatened catfish, Mystus cavasius was carried out at different stocking densities in earthen nursery ponds. Twelve‐day‐old fry were stocked at 200 000 ha^?1 in treatment‐1 (T₁), 250 000 ha^?1 in treatment‐2 (T₂) and 300 000 ha^?1 in treatment‐3 (T₃) respectively. The mean length and weight of fry at stocking was 1.24 ± 0.25 cm and 0.11 ± 0.04 g respectively. Fry in all the experimental ponds were supplemented with SABINCO nursery feed for the first 14 days and starter‐I feed for days 15–56. The physico‐chemical parameters and plankton population of pond water were within the suitable level for fish culture. Growth in terms of final weight, final length, weight gain, length gain and specific growth rate and survival of fingerlings were significantly higher in T₁ than those in T₂ and T₃. Feed conversion rate was significantly lower in T₁ followed by T₂ and T₃ in that order. Significantly higher number of fingerlings was produced in T₃ than that in T₂ and T₁. Even then, consistently higher net benefits were obtained from T₁ than those from T₃ and T₂. Among the treatments evaluated, 200 000 fry ha^?1 was the best stocking density considering the highest growth, production and net benefits of fingerlings of M. cavasius in nursery ponds.     

Influence of dietary protein levels on growth performance and body composition of African bonytongue fingerlings,Heterotis niloticus (Cuvier, 1829)

Two experiments were conducted to examine the influence of dietary protein levels on growth and carcass proximate composition of Heterotis fingerlings. Four isoenergetic practical diets were formulated to contain dietary protein levels from 250 to 400 g kg^?1 diet. Replicate groups of young Heterotis (initial live weight 3.96 and 26.40 g in experiments 1 and 2 respectively) were handfed twice daily to apparent satiation for a period of 42 and 28 days respectively. Statistical analysis revealed that growth rate was significantly affected by dietary protein level (P < 0.01). The highest weight gain was observed in fingerlings fed with 300 and 350 g protein kg^?1 diet for fish size ranging between 3–15 and 26–62 g respectively. There was no significant difference between groups fed with 300, 350 and 400 g protein kg^?1 diet for Heterotis fingerlings (3–15 g) in the one hand; in the other hand, significant differences were found between fish (26–62 g) fed with 350 g protein kg^?1 diet and those receiving 300 and 400 g protein kg^?1 diet, with no significant difference between each other. The specific growth rate varied from 2.4% to 3.1% day^?1. The whole‐body protein, lipid, moisture and ash contents were not significantly affected by dietary protein levels (P > 0.05). The relationships between percentage weight gain and dietary protein levels suggested very similar dietary protein requirement (about 310 g crude protein kg^?1 diet) for Heterotis ranging from 3 to 62 g. The maximum growth occurred at about 345 g protein kg^?1 diet.     

Non-gelatinized corn supplemented with α-amylase at sub-optimum protein level enhances the growth of Labeo rohita (Hamilton) fingerlings

A feeding trial was conducted for 60 days to delineate the effect of both gelatinized and non‐gelatinized corn with or without supplementation of exogenous α‐amylase at two level of protein 35% (optimum) and 27% (sub‐optimum) on growth, tissue composition and protein sparing effect of carbohydrate in the diet of Labeo rohita fingerlings. Three hundred and sixty fingerlings (average weight 10.00±0.15 g) were randomly distributed in 12 treatment groups with two replicates for each. Twelve semi‐purified diets containing either 35% or 27% CP were prepared with different levels of α‐amylase (0, 50, 100 and 150 mg kg^?1) and starch type [gelatinized (G)/non‐gelatinized, (NG)] viz. T₁ (NG, 35% CP, 0 mg kg^?1α‐amylase), T₂ (G, 35% CP, 0 mg kg^?1α‐amylase), T3 (NG, 27% CP, 50 mg kg^?1α‐amylase), T₄ (NG, 35% CP, 50 mg kg^?1α‐amylase), T₅ (G, 27% CP, 50 mg kg^?1α‐amylase), T₆ (G, 35% CP, 50 mg kg^?1α‐amylase), T₇ (NG, 27% CP, 100 mg kg^?1α‐amylase), T₈ (NG, 35% CP, 100 mg kg^?1α‐amylase), T₉ (G, 27% CP, 100 mg kg^?1α‐amylase), T₁₀ (G, 35% CP, 100 mg kg^?1α‐amylase), T₁₁ (NG, 27% CP, 150 mg kg^?1α‐amylase) and T₁₂ (NG, 35% CP, 150 mg kg^?1α‐amylase). The fish were acclimatized to the experimental condition for 24 days during which control diet (NG, 35% CP) was fed. Weight gain percentage, specific growth rate, protein efficiency ratio and apparent net protein utilization of NG corn‐fed groups at 42.43% were significantly higher (P<0.05) than the same level of G corn‐fed groups. We conclude that 42.43% NG corn supplemented with 50 mg α‐amylase kg^?1 feed at sub‐optimum level of CP (27%) significantly enhanced the growth and protein in L. rohita fingerling. Addition of dietary α‐amylase to G corn had no added advantage on growth of L. rohita fingerling.     

Optimum protein-to-energy ratio for two size groups of rabbitfish, Siganus canaliculatus (Park)

Three approximately isoenergetic (17 kJ g^?1) diets were formulated with dietary protein levels of 270, 360 and 480 g kg^?1 (DM basis) providing protein-to-energy ratios of 15.69, 20.48 and 27.16 mg crude protein (CP) kJ^?1, respectively. The effects of these diets on several growth and nutritional parameters were evaluated for the fry (2.50 ± 0.184 g) and fingerlings (11.53 ± 0.023 g) of Siganus canaliculatus (Park). Maximum growth and best feed utilization efficiency of fry were obtained using the diet containing 480 g kg^?1 protein and P:E ratio of 27.16 mg CP kJ^?1. For fingerlings the best results were obtained with the diet containing 360 g kg^?1 protein and P:E ratio of 20.48 mg CP kJ. Body composition of the fry was not affected by the feeding regime whilst the effect was evident in the fingerling groups. The carcass protein content of the fingerling was observed to increase with increasing P:E ratios while lipid content decreased as P:E increased.     

Effects of canola meal on physiological and biochemical parameters in rainbow trout (Oncorhynchus mykiss)

Rainbow trout (initial body weight 4.16 ± 0.25 g) were fed diets [crude protein 420 g kg^?1; gross energy 18.7 MJ kg^?1 dry matter (DM); crude fat 110 g kg^?1] containing graded levels of either a canola meal (crude protein 350 g kg^?1 DM) supplemented with DL‐methionine as partial fish meal protein. A growth trial was conducted over 16 weeks at a water temperature of 12 ± 1 °C. At the end of the growth trial, in addition to body composition analyses, plasma tri‐iodothyronine (T₃) and thyroxine (T₄), cholesterol and liver fatty acid composition were measured. Replacement of fish meal with canola meal (100–570 g kg^?1 replacement) did not affect on growth performance. At 16th week, plasma cholesterol levels were reduced in fish fed all diets in comparison with 8th week. Plasma T₄ levels were significantly higher in the canola meal‐fed fish sampled after 16 weeks, but no significant differences in T₃ levels were obtained (P > 0.05). Proximate compositions were affected by dietary treatments. The liver fatty acid composition reflected that of the diet with a higher level of polyunsaturated (n‐6) fatty acids in fish fed diet canola meal and a higher content in n‐3/n‐6 ratio in fish fed diet without canola meal. These studies show that canola meal has potential to replace substantial levels of fish meal in diets for carnivorous fish without compromising performance.     

Protective effects of basil (Ocimum basilicum) ethanolic extract supplementation diets against experimental Aeromonas hydrophila infection in common carp (Cyprinus carpio)

This study evaluated the effects of basil (Ocimum basilicum) leaves extract supplement on growth, blood parameters and resistance to Aeromonas hydrophila in Cyprinus carpio fingerlings. Basil leaves were mixed thoroughly with feed at 0, 100, 200, 400, 800 and 1600 mg kg^?1 of diet and were fed in triplicate group for 2 months. At the end of this period, growth performance and survival were determined. Then fish were challenged intraperitoneally with A. hydrophila and mortalities were recorded up to 10 days post challenge. Results indicated that WBC, RBC, Ht, Hb, total protein, albumin and globulin were higher (P < 0.05) in fish fed diets containing O. basilicum compared with the control. Highest specific growth rate values were observed in 400 mg kg^?1 group. Feed conversion ratio was significantly lower (P < 0.05) in fingerlings fed 400 and 800 mg O. basilicum kg^?1 dry diet. After 10 days post challenge, total protein, WBC, RBC and Hb were significantly higher in 400 mg kg^?1 compared with other groups. These results reveal that a dietary O. basilicum leaves extract of 400 mg kg^?1 fed for 60 days leads to increased growth performance and survival rate as well as improved feeding efficiency in common carp fingerlings rendering them more resistant against infection by A. hydrophila.     

Effect of dietary protein levels on growth,feed utilization and carcass composition of endangered bagrid catfish Horabagrus brachysoma (Gunther 1864) fingerlings

An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg^?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg^?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg^?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg^?1 diet.     

The potential of deoiled sal (Shorea robusta) seed meal as a feedstuff in pelleted feed for Indian major carp, rohu, Labeo rohita (Hamilton), fingerlings

Ten isonitrogenous (350 g kg^1-crude protein) diets incorporating raw and soaked deoiled sal (Shorea robusta) seed meal at 200, 300,400, 500 and 600 g kg^?1 into a fish-meal-based diet were fed to rohu, Labeo rohita (Ham.), fingerlings for 60 days and fish performance was studied. Tannin from raw salseed meal could be reduced from 34 to 7 g kg^?1 by soaking in water for 16 h at room temperature. In terms of growth response, food conversion ratio and protein efficiency ratio, a diet containing 200 g kg^?1 soaked salseed meal resulted in significantly (P < 0.01) the best performance of the fish. Apparent protein digestibility (APD) values decreased with increasing level of oilseed meal. Carcass protein was highest in fish fed diets containing 200 g kg^?1 soaked salseed meal. The results showed that deoiled salseed meal can be incorporated in carp diets up to 200 g kg^?1 and 300 g kg^?1 in raw and treated forms respectively.     

Effect of different feeds on the growth,survival and reproductive performance of zebrafish,Danio rerio (Hamilton, 1822)

Present experiment was conducted to determine the effect of different feeds with varying protein levels on the growth, survival and reproductive performance of zebrafish, Danio rerio. The control diet (T1) was wild‐collected zooplankton from local fish ponds, while test diets with 350 g kg^?1 protein (T2), 400 g kg^?1 protein (T3) and 450 g kg^?1 protein (T4) were formulated and fed to fish for a period of 210 days. The significantly (P < 0.05) highest mean weight gain and specific growth rate were observed in T1, which were similar with T3 and T4. The significantly (P < 0.05) highest number of egg production per female and relative fecundity were found in T1, followed by T4 and T3 while T2 produced lowest number of eggs. No significant (P > 0.05) differences were observed in brood survival rate, fertilization and hatching rate among the dietary treatments. The highest (P < 0.05) fry survival rate was recorded in T1, followed by T3 and T4. Thus, it is suggested that control diet i.e. mixed zooplankton exhibited better growth, reproductive performance and fry survival rate. However, diet containing 400 g kg^?1 crude protein also gave comparable results in terms of growth, survival and reproductive performance of zebrafish.     

Effects of dietary nano and macro iron oxide (Fe2O3) on the growth,biochemical, and hematological profiles of African catfish (Clarias gariepinus) fingerlings

Effects of nano and macro iron oxide as dietary iron sources on the growth, hematological, and biochemical characteristics of African catfish, Clarias gariepinus, fingerlings have been studied. Conventional basal feed was supplemented with nFe₂O₃ and Fe₂O₃ as treatments T₁ and T₂ (each at 0.0, 0.2, 0.4, 0.8, 1.2, and 1.6 g/kg supplementation levels) and given to C. gariepinus fingerlings (initial average weight and length 5.01 ± 0.80 g and 7.0 ± 0.53 cm respectively) for 7 weeks. After 7 weeks, the highest percent weight gains of 395.6% for T₁ and 767.4% for T₂ occurred simultaneously at the supplementation level of 0.4 g Fe kg^?1 dry feed of both treatments, while the highest value for the control was 332.5%. Iron accumulations in liver were 2.727, 1.443, and 1.225 ppm, and red blood cell counts were 2.3, 6.0, and 7.0 x 10¹²/l for the same treatments. Supplementation of iron oxide in both nano and macro forms significantly improved the growth and health indices of C. gariepinus up to a concentration of 0.4 g Fe kg^?1 dry feed. Also macro iron oxide was more effective than the nano form in enhancing fish growth within the supplementation levels (0.2?1.6 g kg^?1) considered.     

Dietary histidine requirement of fingerling Indian major carp, Cirrhinus mrigala (Hamilton)

An 8‐week growth trial was conducted to determine the dietary histidine requirement of the Indian major carp, Cirrhinus mrigala fingerling (length 4.22 ± 0.45 cm; weight 0.61 ± 0.08 g; n = 40). Isonitrogenous (400 g kg^?1 crude protein) and isoenergetic (17.90 kJ g^?1 gross energy) diets with graded levels of l ‐histidine (2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 g kg^?1 dry diet) were formulated using casein and gelatin as a source of intact protein, supplemented with l ‐crystalline amino acids. Twenty fish were randomly stocked in 70‐L indoor polyvinyl circular fish tank (water volume 55‐L, water exchange rate 1–1.5 L min^?1) and fed experimental diets at the rate of 5% of their body weight/day divided over two feedings at 08:00 and 16:00 h. Maximum live weight gain (295%), best feed conversion ratio (FCR) (1.48) and protein efficiency ratio (PER) (1.69) occurred at 7.5 g kg^?1 of dietary histidine level. When live weight gain, FCR and PER data were analysed using second‐degree polynomial regression, the break points indicated histidine requirements at 9.4, 8.6 and 8.5 g kg^?1 of dry diet respectively. Significantly (P < 0.05) higher whole body protein and low moisture values were recorded at 7.5 g kg^?1 histidine level. Body fat increased significantly (P < 0.05) with increasing histidine levels. However, at 7.5 and 10 g kg^?1 histidine diets body fat did not differ (P > 0.05) to each other. Ash content of fish fed diets containing various levels of histidine did not differ except at 2.5 and 5.0 g kg^?1 inclusion levels where significantly (P < 0.05) higher ash was recorded. Protein deposition was also found to be significantly (P < 0.05) higher in the 7.5 g kg^?1 histidine diet. Based on the polynomial regression analysis of FCR and PER data, it is recommended that the diet for fingerling C. mrigala should contain histidine at 8.5 g kg^?1 of dry diet, corresponding to 21.25 g kg^?1 of dietary protein for optimum growth and efficient utilization of feed.     

Protective effects of a synbiotic against experimental Saprolegnia parasitica infection in rainbow trout (Oncorhynchus mykiss)

A combination of probiotics and prebiotics as synbiotics allows assessing their synergistic effects. This study evaluated the effects of a synbiotic supplement on growth performance, haematological parameters and resistance to Saprolegnia parasitica in rainbow trout, Oncorhynchus mykiss (Walbaum) fingerlings. Fish fed a dietary synbiotic in three levels of 0.5, 1.0 and 1.5 g kg^?1 thrice a day. The fingerlings were challenged with Saprolegnia parasitica after 60 days post feeding and their mortalities recorded up to 15 days. The fingerlings at all three experimental treatments showed significant (P < 0.05) increases in final mean weights and specific growth rates (SGR). The best feed conversion ratio (FCR), feed conversion efficiency (FCE) and maximum survival rate were also obtained by the fish fed 1.0 g synbiotic kg^?1 diet. Furthermore, supplementation with synbiotic significantly increased blood factors at all treatments. After challenges with Saprolegnia parasitica, the synbiotic‐fed groups showed significantly higher survival rates compared with the control group. These results reveal that a dietary synbiotic of 1.0 g kg^?1 fed for 60 days leads to increased growth performance and survival rate as well as improved feeding efficiency in rainbow trout fingerling, rendering them more resistant against infection by Saprolegnia parasitica.     

Evaluation of Cassia fistula meal as a replacement for soybean meal in practical diets of Oreochromis niloticus fingerlings

This study was undertaken to determine the replacement value of Cassia fistula seed meal (CFM) for soybean meal (SBM) in practical diets of Oreochromis niloticus fingerlings. Five practical diets (350 g kg^?1 crude protein) containing 0 g kg^?1 (control), 170 g kg^?1 (diet II), 340 g kg^?1 (diet III), 509 g kg^?1 (diet IV) and 670 g kg^?1 (diet V) substitution levels of CFM for SBM were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 10.22 ± 0.03 g) for 70 days. Fish mortality increased linearly with increase in inclusion levels of CFM in the diet. Growth and diet utilization efficiency were depressed in fish fed diets containing CFM at varying inclusion levels. Feed conversion ratio, specific growth rate and protein efficiency ratio of O. niloticus fed on diet containing 170 g kg^?1 substitution level of CFM were similar (P > 0.05) to the control diet. Digestibility of the different diets decreased with increase in inclusion levels of CFM. Fish fed diet containing 670 g kg^?1 CFM had significantly lower carcass protein. However, no significant differences were observed in carcass protein and lipid contents between fish fed the control diets and diet containing 170 g kg^?1 CFM. The most efficient diet in terms of cost per unit weight gain of fish was obtained in 170 g kg^?1 CFM dietary substitution.     

Dietary arginine requirement of fingerling Indian major carp, Cirrhinus mrigala (Hamilton)

Dietary arginine requirement of fingerling Indian major carp, Cirrhinus mrigala (4.20 ± 0.05 cm; 0.60 ± 0.02 g) was determined by conducting a 8‐week feeding trial with casein–gelatine‐based diets (400 g kg^?1 crude protein; 17.90 kJ g^?1, gross energy), containing crystalline amino acids with graded levels of l ‐arginine (10, 12.5, 15, 17.5, 20 and 22.5 g kg^?1, dry diet). Fish were randomly stocked, in triplicate groups, in 55‐L indoor polyvinyl flow through circular tanks and fed experimental diets at 5% of their body weight divided into two feedings at 08.00 and 16.00 hours. Live weight gain (321%) and feed conversion ratio (FCR 1.40) were significantly (P < 0.05) higher in fish fed diet containing 17.5 g kg^?1dietary arginine compared with other diets. Second‐degree polynomial regression analysis of live weight gain, FCR and protein efficiency ratio data indicated requirements for dietary arginine at 18.7, 18.4 and 18.3 g kg^?1 of the dry diet, respectively. Maximum carcass protein, and minimum moisture and fat contents were noticed at the requirement level. Carcass ash content remained insignificantly different among the treatments except at 17.5 g kg^?1 dietary arginine showing significantly higher ash content. Based on the above results, it is recommended that the diet for fingerling C. mrigala should contain arginine at 18.4 g kg^?1, dry diet, corresponding to 46 g kg^?1 dietary protein for optimum growth and efficient feed utilization.     

Utilization of gelatinized carbohydrate in diets of Labeo rohita fry

A total of 180 Labeo rohita fry (≈1 g) were distributed into six treatment groups with three replicates each. Six isoenergetic (15.8 kJ g^?1) diets were prepared with varying levels of protein (CP) and gelatinized carbohydrate (GC), viz. D₁: 450 g kg^?1 CP, 258 g kg^?1 GC; D₂: 400 g kg^?1 CP, 302 g kg^?1 GC; D₃: 350 g kg^?1 CP, 399 g kg^?1 GC; D₄: 301 g kg^?1 CP, 447 g kg^?1 GC; D₅: 249 g kg^?1 CP, 517 g kg^?1 GC and control diet, D₆: 400 g kg^?1 CP, 468 g kg^?1 GC and these were fed to fish at 40 g kg^?1 wet body weight per day for 60 days. Highest growth was recorded for fish fed D₄, decreasing for D₅. Protein utilization, amylase activity and carbohydrate digestibility were significantly positively correlated with GC (P < 0.05) and were highest in fish fed D₅. Hypertrophy of hepatic cells was only recorded for D₅. Lysine, which may be affected during gelatinization, was estimated in diets and found to be above the minimum level required. Survival rate was unaffected by diet. The results of the present study indicate that a diet containing 450 g kg^?1 GC and 300 g kg^?1 CP was efficiently utilized by L. rohita fry.     

Mineral status of Pangasius pangasius (Hamilton) fingerlings in relation to supplemental phytase: absorption, whole-body and bone mineral content

A 60‐day feeding trial was conducted to quantify the effects of microbial phytase supplementation on apparent absorption, whole body and bone contents of minerals in Pangasius pangasius fingerlings. Seven isoprotein (35.67%) and isocaloric (3870 kcal kg^?1) diets were prepared with graded levels of supplemental phytase at 0 (T₁), 150 (T₂), 250 (T₃), 350 (T₄), 500 (T₅), 1000 (T₆) and 2000 (T₇) FTU (Phytase Units) kg^?1. Three hundred and fifteen fingerlings of P. pangasius (1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. There was significant increase (P<0.05) in tissue protein content in phytase‐supplemented groups compared with the control. Apparent absorptions of calcium (Ca), phosphorus (P), magnesium (Mg), manganese (Mn), zinc (Zn), iron (Fe), potassium (K), copper (Cu) and cobalt (Co) were significantly (P<0.05) higher in the phytase‐supplemented groups than the control group. Faecal ash and P contents were significantly (P<0.05) higher in the control (T₁) than the phytase‐supplemented groups. Whole‐body contents of Ca, P, Zn, Fe, Cu and Co were significantly (P<0.05) improved by the dietary supplementation of phytase‐barring Mg and Mn. Concentrations of bone Ca, P, K, Cu and Co were significantly (P<0.05) higher in phytase‐supplemented groups. Bone ash contents (40.77–44.85%) were increased concomitantly with the increased level of phytase inclusion upto 500 FTU kg^?1 diet. It was observed that a minimum dose of 250 FTU phytase kg^?1 diet improved the mineral absorption and utilization in P. pangasius fingerlings.     

Effect of dietary lipid and protein levels with different protein to energy ratios on growth performance,feed utilization and body composition of Rutilus frisii kutum (Kamenskii, 1901) fingerlings

A 3 × 5 factorial design including three lipid levels (100, 130 and 180 g kg^?1 diet, based on dry matter) and five dietary protein levels (370, 420, 470, 520 and 570 g kg^?1 diet, based on dry matter) was conducted to investigate the optimum dietary lipid and protein requirements for Rutilus frisii kutum fingerlings. Triplicate groups of 80 kutum (500 ± 60 mg initial weight) were stocked in 250‐l tanks and fed to apparent satiation thrice daily for 8 weeks. The results showed that the growth performance and feed utilization were significantly (P < 0.05) affected by dietary protein and lipid levels. Weight gain, specific growth rate and feed conversion ratio of kutum improved significantly with increasing protein level from 370 to 470 g protein kg^?1 diet, but there was a significant decrease in growth parameters with increasing protein level from 470 to 570 g protein kg^?1 diet. Also, the higher values of weight gain, specific growth rate and better feed conversion ratio were observed for fish fed diets containing 130 g kg^?1 lipid diet. The results of this study showed that diet containing 420 g kg^?1 protein and 130 g kg^?1 lipid with a P:E ratio of 19.22 mg protein kJ^?1 of gross energy is optimal for kutum fingerlings.     

Effects of diet supplementation of soya‐saponins,isoflavones and phytosterols on Atlantic salmon (Salmo salar,L) fry fed from start‐feeding

A 14‐week trial was conducted to investigate the effects of antinutritional factors (ANFs) commonly present in soybean ingredients, singly and in combination, on Atlantic salmon (Salmo salar L.) fed from start‐feeding. The experimental diets consisted of a negative control fish meal diet (FM), and a positive control diet with 167 g kg^?1 soybean meal inclusion (SBM) and four diets based on the FM diet supplemented with 2 g kg^?1 soya‐saponins (SAP), 1.5 g kg^?1 isoflavones (IFL), 0.3 g kg^?1 phytosterols (PHS) or a mixture of these (MIX). Fish fed the SAP diet showed significantly higher growth performance than those fed FM, while the IFL treatment significantly decreased growth performance of salmon fry. Fish fed the IFL diet had significantly lower maltase activity and higher trypsin activity in proximal intestine than fish fed the FM diet. Histological differences were observed in the liver of fish fed the IFL diet, characterized by reduced size of the hepatocytes. Fish fed the PHS and IFL diets showed the highest frequencies of skeletal deformities among the six treatments. In conclusion, the results indicate that purified isoflavones may negatively affect growth performance, intestinal function, liver metabolism and bone formation of salmon fry.     

Effects of different dietary protein and lipid levels on growth, feed utilization and body composition of red porgy (Pagrus pagrus) fingerlings

Two feeding trials were conducted to determine the minimum dietary protein level producing maximum growth, and the optimum protein to energy ratio in diets for red porgy (Pagrus pagrus) fingerlings, respectively. In the first trial, six isoenergetic diets were formulated with protein levels ranging from 400 to 650 g kg^?1 in increments of 50 g kg^?1, and fed for 11 weeks to 2.8 g average initial weight fish. Weight gain, specific growth rate and feed efficiency were significantly higher with diets containing higher protein levels, when compared with dietary levels below 500 g kg^?1. The highest protein efficiency ratios were obtained in fish fed 500 g kg^?1 dietary protein. The minimum dietary protein level producing maximum fish growth was found to be 500 g kg^?1. In the second trial, 15 g average initial weight fish were fed for 12 weeks, six diets containing three different lipid levels (100, 150 and 200 g kg^?1) combined with two protein levels (450 and 500 g kg^?1). Weight gain values increased when dietary lipids increased from 100 to 150 g kg^?1, with a further decrease for 200 g kg^?1 lipids in diets; the lowest fish growth being supported by 200 g kg^?1 dietary lipids. Fish growth was significantly higher when dietary protein increased from 450 to 500 g kg^?1. There was no evidence of a protein‐sparing effect of dietary lipids. Liver protein and lipid contents were low when compared with other fish species. All diet assayed produced high liver glycogen accumulation. The recommended protein and lipid levels in diets for red porgy fingerlings were 500 and 150 g kg^?1, respectively.