Dietary dehulled soybean meal as a replacement for fish meal in fingerling and growing olive flounder Paralichthys olivaceus (Temminck et Schlegel)

Two experiments were conducted to determine the optimum dietary inclusion level of dehulled soybean meal (DHSM) as a fish meal (FM) replacement in diets for olive flounder Paralichthys olivaceus. All the experimental diets were formulated to be isonitrogenous and isoenergetic to contain 50% crude protein (CP) and 16.7 kJ energy g^?1 diet. In the first experiment, eight diets were formulated to replace FM with DHSM at 0%, 10%, 20% without amino acid (AA) supplementation; 20%, 30%, 40% with AA supplementation and 30%, 40% with AA & attractant supplementation (DHSM₀, DHSM₁₀, DHSM₂₀, DHSM_20+AA, DHSM_30+AA, DHSM_30+AA+Att, DHSM_40+AA, DHSM_40+AA+Att respectively). Triplicate groups of 25 fish averaging 5.0±0.04 g (mean±SD) were fed one of eight experimental diets for 8 weeks. In the second experiment, six diets were formulated to replace FM with DHSM at 0%, 10%, 20%, 30% without attractant supplementation and 20%, 30% with attractant supplementation (DHSM₀, DHSM₁₀, DHSM₂₀, DHSM₃₀, DHSM_20+Att, DHSM_30+Att respectively). Triplicate groups of 15 fish averaging 45.5±0.08 g (mean±SD) were fed one of six experimental diets for 10 weeks. Based on growth performance, we concluded that DHSM could replace FM up to 20% without AAs (lysine and methionine) and attractant supplementation, and up to 30% with AAs and/or attractant supplementation in diets for fingerling and growing olive flounder.     

Balance trials with African catfish Clarias gariepinus fed phytase-treated soybean meal-based diets

Balance trials were conducted with African catfish Clarias gariepinus to assess the effect of phytase treatment of soybean meal-based diets on growth, feed utilization and nutrient budgets. Isocaloric (20–22 kJ g⁻¹) and isonitrogenous (47–50% protein) diets were tested. In a first experiment the control diet (58% fish meal and 18% soybean meal) was compared with two diets containing 6% fish meal and 69% soybean meal, and two diets containing 29% fish meal and 41% soybean meal. One of each of these two diets had been pretreated with phytase (1000 units per kg dry diet). In the second experiment, the control diet (6% fish meal and 69% soybean meal, pretreated with 1000 units phytase kg⁻¹ dry diet) was compared with four diets that were similar in composition but supplemented with increasing amounts of phytase (15, 380, 750, 1000 units kg⁻¹ dry diet). Replacement of fish meal by soybean meal in the first experiment led to a depression in growth rate and feed utilization parameters. Results of both experiments clearly indicated a positive effect of phytase treatment, particularly on phosphorus digestibility and retention, and consequently the phosphorus conversion efficiency and the phosphorus budget. No differences in these parameters were found between addition of equal amounts of phytase by pretreatment or supplementation.     

Partial replacement of fish meal by soybean meal with or without methionine and phytase supplement in diets for juvenile Chinese sucker,Myxocyprinus asiaticus

This study was designed to evaluate the effects of using soybean meal supplemented with or without methionine (M) and graded levels of phytase (P) to replace high‐level (60%) fish meal in the diets for juvenile Chinese sucker. Seven experimental diets (about 430 g kg^?1 crude protein on dry matter basis) were formulated from practical ingredients. The control diet (FM) was formulated to contain 400 g kg^?1 white fish meal (FM), whereas in the other six diets (diets 2–7), soybean meal (SBM) was used to replace 60% fish meal with or without methionine (3 g kg ^?1) and 0,500, 1000, 1500 and 2000 U kg^?1 phytase (designated as SBM, SM, SMP500, SMP1000, SMP1500 and SMP2000, respectively). Results from the feeding trial indicated that SBM without any methionine or phytase supplement replacing about 60% FM significantly affected the growth of fish (P < 0.05). Weight gain of fish fed diet SM was significantly higher than the fish fed diet SBM, but still much lower than fish fed the control diet (P < 0.05). SBM with methionine and phytase supplement significantly improved the growth of fish and apparent digestibility coefficients of phosphorus compared with the groups which fed diet SBM and diet SM (P < 0.05). Weight gain of fish fed SMP1000, SMP1500 and SMP2000 had no significant difference than fish fed control diet. Furthermore, fish fed SMP1500 showed optimum weight gain and ADC of phosphorus between these three groups. This suggested that soybean meal with 3 g kg^?1 methionine and 1500 U kg^?1 phytase supplement could successfully replace 60% fish meal in the diet for juvenile Chinese sucker without affecting growth and enhanced the apparent digestibility coefficient of phosphorus.     

Effects of fish oil and partial fish meal substitution with oilseed oils and meals on growth performance, nutrient utilization and health of the rainbow trout Oncorhynchus mykiss

A feeding trial was conducted to investigate the effects of the replacement of dietary fish meal and fish oil with oilseed meals (soybean or canola) and canola oil on growth, nutrient utilization, body composition, diet digestibility and hematological parameters of rainbow trout Oncorhynchus mykiss. Seven diets were used; the control diet (designated FM) contained fish meal and fish oil as the main protein and lipid sources. For the experimental diets, 40% of fish meal protein was substituted with soybean meal, canola meal or a soybean/canola meal mixture, and these diets (designated SM, CM and SCM, respectively) contained fish oil as the lipid source. Three additional diets (SM?+?CO, CM?+?CO and SCM?+?CO) were formulated with the same vegetable protein meals but with fish oil replaced by canola oil. Fish were fed twice daily to apparent satiation for 11?weeks. The growth of fish fed the CM?+?CO diet was significantly lower than that of fish fed the FM, SCM, SM?+?CO and SCM?+?CO diets. The feed conversion ratio (FCR) was significantly better in fish fed the FM and SCM?+?CO diets than in fish fed the CM and CM?+?CO diets. Furthermore, feed intake was significantly lower for fish fed the CM?+?CO diet than in fish fed the SCM diet, and lipid digestibility of the CM?+?CO diet was significantly lower than that of all other diets. No significant differences of body composition were observed. Circulating leukocyte levels, leukocyte ratios and serum lysozyme activity remained unaffected by dietary treatment. However, it was observed that fish fed the CM?+?CO diet displayed hematocrit levels significantly lower (P?<?0.05) than that of fish fed the other diets. The results indicate that when diets contain either fish oil or canola oil, canola meal and soybean meal can be incorporated into rainbow trout feeds at a combined 32% inclusion level (replacing 40% of fish meal protein) without inducing significant negative effects on growth, nutrient utilization or health.     

Total replacement of fish meal with animal protein sources in Nile tilapia,Oreochromis niloticus (L.), feeds

The effects of total replacement of dietary fish meal (FM) with animal protein sources on the growth, feed efficiency and profit indices of Nile tilapia, Oreochromis niloticus (L.), were investigated. Shrimp meal (SM), blood meal (BM), meat and bone meal (MBM), BM + MBM mix and poultry by-product meal (PBM) replaced FM in six isonitrogenous (30% crude protein), isocaloric (400 kcal GE 100 g^–1) diets. The diets were fed to O. niloticus fingerlings (12.5 g) to satiation twice a day for 150 days. The growth of fish fed SM, PBM and MBM was not significantly different from those fed the FM-based diet, while feed conversion and protein efficiency ratios were significantly retarded. Further reduction in fish performance was noticed when BM or BM + MBM replaced FM in the control diet. Cost–benefit analyses of the test diets indicated that these sources were economically superior to FM. The PBM-based diet produced higher carcass lipid than other diets. Fish fed SM, MBM and PBM diets had significantly higher ash contents (P < 0.05).     

Supplemental iron and phosphorus increase dietary inclusion of cottonseed and soybean meal in olive flounder (Paralichthys olivaceus)

A long‐term feeding experiment was conducted to investigate the use of cottonseed and soybean meal (CS) with iron and phosphorus supplements in diets for olive flounder (Paralichthys olivaceus). Olive flounder with an initial average size of 28.5 ± 0.35 g (mean ± SD) were divided into 15 groups (three tanks per dietary treatment) and fed 480 g kg^?1 crude protein diets in which each of five isonitrogenous diets was formulated to contain different levels of cottonseed/soybean meal (1 : 1) to replace fish meal (FM) with iron and phosphorus supplementations. The five experimental diets were as follows: diet 1 (control), 0%CS; diet 2, 20%CS; diet 3, 30%CS; diet 4, 30%CS + Fe&P; and diet 5, 40%CS + Fe&P. After 26 weeks of feeding trial, no significant differences were observed in weight gain, feed utilization and survival among all the treatments. The total gossypol accumulation in liver of fish fed diets supplemented with iron was significantly lower than that of fish fed diets without supplementation of iron. The results indicate that the addition of iron in diets could prevent the absorption of free gossypol. The findings in this study suggest that dietary supplements of iron and phosphorus could increase the inclusion of cottonseed and soybean meal for FM replacement in diets for marine fish species.     

Top-spraying soybean meal-based diets with phytase improves protein and mineral digestibilities but not lysine utilization in rainbow trout, Oncorhynchus mykiss (Walbaum)

Two digestibility trials and two growth trials were carried out to evaluate the influence of top‐sprayed phytase on apparent digestibility coefficients (ADCs) of protein and mineral and utilization in rainbow trout fed with soybean meal‐based diets. In Trial 1, a semi‐purified diet containing 50% soybean meal was supplemented with graded levels of phytase (0, 500, 1000, 2000 and 4000 U kg^?1 diet), and fed to triplicate groups of fish. In Trial 2, commercial‐type extruded feeds containing 36% soybean meal with either 0 or 2000 U phytase kg^?1 were fed to five replicate groups of fish. Phytase clearly decreased phytic acid content of feces from 35 to 5 mg and from 34 to 14 mg phytic acid per g faecal dry matter in Trials 1 and 2 respectively. Apparent digestibility coefficient of P improved from 23% to 83% in Trial 1 and from 35% to 54% in Trial 2 by phytase. Apparent protein increased by 1.2% and 3.2%‐units by phytase in Trials 1 and 2. Zinc digestibility was significantly increased in Trial 1, but not in Trial 2. Trials 3 and 4 were conducted to evaluate the influence of phytase on dietary P (Trial 3) and lysine (Trial 4) utilization. Three diets were prepared for each trial: P (Trial 3)‐ or lysine (Trial 4)‐deficient basal diets, basal diets with phytase supplementation (2000 U kg^?1) and P (Trial 3)‐ or lysine (Trial 4)‐fortified diets. Rainbow trout (initial weight 20 g) were fed for 10 weeks using four and six replicates for Trials 3 and 4 respectively. Phytase increased P utilization in Trial 3 as demonstrated by an increase in vertebra ash from 24.1% to 45.4%, and by an increase in weight gain from 243% to 459% of the initial weight. Phytase did not increase lysine utilization, since neither protein retention nor weight gain were enhanced by phytase. Supplemental lysine increased protein retention and weight gain to 43.1% and 514%, respectively, and also decreased whole‐body lipid contents significantly from 120 to 123 g kg^?1 in fish fed the basal diet and phytase‐supplemented diet to 106 g kg^?1 in fish fed with lysine‐fortified diet.     

Utilisation of diets supplemented with microbial phytase by seabass (Dicentrarchus labrax) juveniles

A trial was carried out to compare the growth performance, body composition and apparent digestibility coefficients (ADC) of diets by seabass, with an initial weight of 13.5 g, fed diets including fish meal (68.6 % of the dietary protein) or soybean meal (65.6 % of the dietary protein) as the main protein sources. Microbial phytase was added to the soybean meal based diet (1 000 and 2 000 IU·kg⁻¹) and to the fish meal based diet (2 000 IU·kg⁻¹) in order to study its effect on phosphorus utilisation. Results of this trial showed that growth rate, feed conversion and nitrogen retention were significantly better in fish fed the fish meal based diet. Energy retention was similar in both groups. ADC of protein were similar among groups. ADC of phosphorus was significantly higher in the fish meal based diet (63 %) than in the soybean meal based diet (25 %). Supplementation of the fish meal based diet with microbial phytase did not improve the ADC of phosphorus, while in the soybean meal based diet the inclusion of 1 000 and 2 000 IU·kg⁻¹ of microbial phytase significantly increased the ADC of phosphorus to 71.5 % and 79.8 %, respectively. It is concluded that for practical purposes supplementation of diets with microbial phytase may prove valuable in diets including high levels of plant feedstuffs.     

Long-term evaluation of extruded diets compared with raw fish moist diet for growing Korean rockfish, Sebastes schlegeli (Hilgendorf)

A long‐term experiment was conducted in sea cages to compare three experimental extruded pellet (EP) diets with a raw fish moist pellet (MP) diet for Korean rockfish, Sebastes schlegeli (Hilgendorf). White fishmeal (WFM), soybean meal (SM) and fishmeal analogue (BAIFA‐M?)‐based experimental EP diets were formulated to be isonitrogenous and isocaloric with 50% crude protein (CP) with available energy of 16.7 kJ g^?1 diet. An MP diet made of 80% frozen horse mackerel + 20% commercial binder meal was also included in the experiment. The proportions of the major protein ingredients in three experimental EP diets were as follows: WFM diet, 100% WFM; SM diet, 70% WFM + 30% SM; BAIFA‐M? diet, 70% WFM + 30% BAIFA‐M?. The experiment was divided into three periods according to fish size: period I, initial weight of 20.2 ± 3.6 g (mean ± SD); period II, initial weight of 57.6 ± 4.7 g (mean ± SD); period III, initial weight of 96.3 ± 6.9 g (mean ± SD). There were no significant differences in weight gain, feed efficiency ratio, thermal‐unit growth coefficient, specific growth rate, haemoglobin, or haematocrit among fish that were fed the four diets during all three periods. However, fish that were fed the MP diet had a lower survival rate than the fish that were fed the other three EP diets for all periods. These results strongly suggest that EP diets could be developed to replace MP diet for the grow‐out stage of production of Korean rockfish without adverse effects on growth performance.     

Dietary microbial phytase supplementation and the utilization of phosphorus, trace minerals and protein by rainbow trout [Oncorhynchus mykiss (Walbaum)] fed soybean meal-based diets

Effects of thermal and enzymatic treatments of soybean meal on apparent absorption of total phosphorus, phytate phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, manganese, strontium and zinc were examined using rainbow trout, Oncorhynchus mykiss (Walbaum), as the test species. Absorption of the test nutrients was estimated using yttrium as an inert non-absorbable indicator. Thermal treatments (microwaving, dry roasting, steam heating, cooking) had no measurable effect on the apparent absorption of phosphorus and other minerals. Phytase supplementation increased the apparent absorption of phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, strontium and zinc in low-ash diets containing soybean meal, but had little effect in high-ash diets containing both soybean and fish meal. In low-ash diets, the apparent absorption of phosphorus increased in accord with the level of phytase added to the diet, from 27% (no phytase added) up to 90% (phytase added, 4000 units kg⁻¹ diet) or 93% (predigested with phytase, 200 units kg⁻¹ soybean meal). In high-ash diets, dietary acidification with citric acid decreased the effect of phytase, whereas in low-ash diets, acidification markedly increased the effect of the enzyme. Excretion of phosphorus in the faeces of fish fed a low-ash diet containing phytase-treated soybean meal was 0.32 g per kg diet consumed, a 95%−98% reduction compared with phosphorus excretion by fish consuming commercial trout feeds.     

Meat and Bone Meal as an Alternative for Fish Meal in Soybean Meal‐Based Diets for Florida Pompano,Trachinotus carolinus L.

Alternative protein feedstuffs are potential surrogates for fish meal in the diet of Florida pompano. This study was designed to evaluate the replacement of fish meal with meat and bone meal in a soybean meal‐based diet for Florida pompano. In Trial I (10 wk), the basal diet (FM15, formulated to contain 40% crude protein and 10% lipid) containing 15% fish meal was modified by the isonitrogenous replacement of fish meal with meat and bone meal producing diets with 10 (FM10), 5 (FM05), and 0% (FM0) fish meal. In Trial II (8 wk), the FM0 served as the basal diet (Tau 0) and was modified by the additive supplementation of taurine to produce three test diets containing 0.25 (Tau 0.25), 0.5 (Tau 0.50), and 0.75% (Tau 0.75) taurine. In Trial I, reduced weight gain (220.1%), feed efficiency (0.31), and survival (84.5%) were observed in fish fed the FM0 diet (P < 0.05). In Trial II, the supplementation of taurine improved the growth performance, survival, and protein and energy retention efficiencies of Florida pompano (P < 0.05). These results indicate that the supplementation of taurine was required in these feed formulations and that meat and bone meal is a good alternative ingredient for fish meal in soybean meal‐based diets for Florida pompano.     

Effect of dietary replacement of fish meal by soybean protein concentrate on growth performance and phosphorus discharging of juvenile black sea bream,Acanthopagrus schlegelii

The 8‐week experiment was conducted to evaluate the effects of partial replacement of fish meal (FM) with soybean protein concentrate (SPC) on juvenile black sea bream, Acanthopagrus schlegelii (10.70 ± 0.04 g). Diets were formulated to replace FM protein by SPC at 0, 8, 16, 24, 32 or 40% (designated as T1, T2, T3, T4, T5 and T6, respectively). Diets except T1 were supplemented with phytase at 2000 phytase activity U kg^?1. The results showed that survival rate, growth performance and feed utilization were not significantly affected by increasing dietary SPC. Fish fed diet T3 had higher feed intake compared to those fed T1, T2 and T5 diets. Whole body compositions of black sea bream were significantly influenced by SPC replacing FM except for protein, ash and phosphorus content. Condition factor of fish was significantly lower in T2 than that of fish in T3 group. Apparent digestibility coefficients (ADCs) of dry matter was higher in fish fed T6 diet than those of fish fed T1 and T2 diets, ADCs of phosphorus increased with dietary SPC level up to T3 and then decreased. The results obtained in this study indicate that FM protein could be effectively replaced by SPC protein with phytase in diet of black sea bream.     

Partial replacement of fish meal by cottonseed meal and soybean meal with iron and phytase supplementation for parrot fish Oplegnathus fasciatus

Two consecutive feeding trials were conducted to determine the optimum dietary level of the cottonseed and soybean meal (CS) for replacement of fish meal (FM) in diets for juvenile and ongrowing parrot fish with or without iron and phytase. In experiment I, juvenile parrot fish (BW: 3.17 g) were fed one of six experimental diets for 12 weeks which were formulated to replace FM protein by equal proportion (1:1, w:w) of CS at 0, 10, 20, 30, 40, or 50% (designated as CS0, CS10, CS20, CS30, CS40, or CS50, respectively). In experiment II, ongrowing parrot fish (BW: 55 g) were fed one of five experimental diets for 9 weeks. The experimental diets were formulated to replace FM protein by CS at 0, 20, or 30% (designated as CS0, CS20, or CS30, respectively) and to include ferrous sulfate (0.1 and 0.2%) and phytase into the CS20 and CS30 diets (CS20 + Fe&P and CS30 +Fe&P, respectively). Results from the two feeding trials indicated that the CS could replace up to 20% FM protein in diets for juvenile parrot fish (3–22 g) and up to 30% in ongrowing (55–120 g) parrot fish. The supplemental effect of iron and phytase was not significant on growth performance. Total or each gossypol enantiomer concentration in the liver increased as the level of dietary cottonseed meal increased. However, gossypol in the liver of fish fed diets supplemented with iron was not detected. The dietary supplementation of CS significantly reduced the levels of plasma triacyglycerols and total cholesterol. The present study indicates that plant protein sources are better utilized in larger fish, and that up to approximately 30% FM protein could be replaced by CS with iron and phytase in the presence of supplemental lysine and methionine.     

Effects of fish meal replaced by fermented soybean meal on growth performance,intestinal histology and microbiota of largemouth bass (Micropterus salmoides)

This study was conducted to investigate the effects of replacing fish meal (FM) with fermented soybean meal (FSM) and soybean meal (SM) on growth performance, intestinal histology and microbiota of largemouth bass (Micropterus salmoides). The basal diet contained 350 g/kg FM (CON), and then, FM was replaced with SM and FSM at the ratios of 30% and 60% (SM‐30, SM‐60, FSM‐30 and FSM‐60), respectively. The largemouth bass (4.43 ± 0.13 g) were fed for 8 weeks. The results showed that weight gain of fish fed with FSM‐60 and SM‐60 diets was significantly lower, and feed conversion ratio of SM‐30, SM‐60 and FSM‐60 groups was significantly higher than the CON group (p < .05). The intestinal villus height of SM‐60 group and the villus width of SM‐60 and FSM‐60 group were significantly lower than the CON group (p < .05). The 30% FM replacement by SM and FSM significantly increased the abundance of Cetobacterium and Mycoplasma, respectively (p < .05). In conclusion, FSM could replace 30% FM in diet without negative impacts on the growth performance of largemouth bass, while the SM should be controlled below 30%.     

Evaluation of dietary soybean meal as fish meal replacer for juvenile whiteleg shrimp,Litopenaeus vannamei reared in biofloc system

Different levels of dietary soybean meal (SBM) as a fish meal (FM) replacer, with and without amino acid supplementation, for whiteleg shrimp, Litopenaeus vannamei reared in the biofloc system was examined in eight weeks of feeding trial. Eight experimental diets consisted of a basal diet with 0% FM replacement by SBM provided in clear sea water without biofloc system (S₀SW), four diets replacing FM at 0% (S₀), 33% (S₃₃), 67% (S₆₇) and 100% (S₁₀₀) by SBM, and three diets replacing FM at 33% (S₃₃A), 67% (S₆₇A) and 100% (S₁₀₀A) by SBM supplemented with amino acids (methionine and lysine) in the seawater biofloc system. Results of water quality analyses showed significantly lower total suspended solids and nitrate for S₀SW group than all other treatments. Diets S₀ and S₃₃A resulted in higher weight gain and specific growth rate among all groups, with no significant differences with S₃₃ group. In addition, whole-body protein and amino acid compositions of shrimp fed S₀SW were lower than most biofloc groups. Haemolymph parameters showed significant differences in total protein, cholesterol and triglyceride between groups S₀ and S₀SW. Also, superoxide dismutase activity showed a decreasing trend with increasing replacement level. In conclusion, based on these results, SBM could replace up to 33% of FM with or without amino acid supplementation in juvenile whiteleg shrimp diets reared in the biofloc system.

     

Partial replacement of fish meal by soy protein concentrates in diets for a new Japanese strain of juvenile soft‐shelled turtle,Pelodiscus sinensis

An 8‐week experiment was conducted to evaluate the effects of dietary fish meal (FM) replaced by soybean protein concentrate (SPC) on Japanese strain of soft‐shelled turtle, Pelodiscus sinensis juveniles. Diets were formulated to replace FM protein by SPC at 0, 15, 30, 45, 60 or 60% supplemented with phytase (2000 FTU kg^?1) (designated as S0, S15, S30, S45, S60 and S60P, respectively), and each diet was fed to triplicate groups. The results showed that the growth was significantly lower when dietary SPC replaced more than 45% FM. The turtles fed the S15 or S30 diet showed comparable feed and protein utilization efficiency compared with the S0 group, whereas more than 30% replacement of FM adversely affected these values. Increasing dietary SPC levels significantly lowered the apparent digestibility coefficients (ADC) of dry matter, protein, lipid, phosphorus and gross energy. Whole‐body protein, ash and phosphorus content showed a declining trend when dietary SPC levels increased, while body lipid and moisture content were unaffected. When the turtles were fed diets with increasing levels of SPC, serum total protein concentration, alkaline phosphatase and catalase activities decreased with a corresponding increase in glutamic pyruvic transaminase activity. Turtles fed the S60P diet showed comparable growth performance and feed utilization efficiency to the S40 group, and were superior to the S60 group. The present study showed that SPC could successfully substitute for 30% FM protein in the diets for P. sinensis juveniles, and the maximum effective substitution may be greater if exogenous phytase was added.     

Use of ideal protein concept for precision formulation of amino acid levels in fish-meal-free diets for juvenile Nile tilapia (Oreochromis niloticus L.)

This study was undertaken in a closed system with Nile tilapia (Oreochromis niloticus) to examine the effects of total replacement of fish meal (FM) by soybean meal. Nile tilapia fingerlings with an average weight of 5.34±0.08 g were hand‐fed one of the five isoenergetic (≈13.5 MJ digestible energy kg^?1) and isoproteic (≈31% of digestible protein) experimental diets to satiation, six times a day during 85 days in eight replicate fibreglass tanks (six fish per tank). The control diet containing FM was substituted by soybean meal, with and without essential amino acids (lysine, methionine and threonine) or dicalcium phosphate supplementation. The supplemental amino acids were added at levels to simulate the reference amino acid profile of Nile tilapia carcass protein, based on the ideal protein concept. The results showed that soybean meal diet supplemented only with dicalcium phosphate was inferior to the control diet with FM and soybean meal diets supplemented with dicalcium phosphate and essential amino acids. Multiple essential amino acids and dicalcium phosphate incorporation in soybean meal diets was associated with performance, whole‐body composition and carcass yield equal to that of the fish fed with the control diet containing FM. These data suggest that a diet with all plant protein source, supplemented with essential amino acids, based on tissue amino acid profile, can totally replace FM in a diet for Nile tilapia, without adverse effects on the growth performance, carcass yield and composition.     

Galactooligosaccharide and a combination of yeast and β-glucan supplements enhance growth and improve intestinal condition in striped catfish <Emphasis Type="Italic">Pangasianodon hypophthalmus</Emphasis> fed soybean meal diets

The effects of galactooligosaccharide (GOS) and a combination of yeast and β-glucan (YβG) supplementation of dietary soybean meal (SBM) on the growth and digestive performance of striped catfish Pangasianodon hypophthalmus were evaluated. Four isonitrogenous (30% protein) and isocaloric (19 MJ/kg diet) diets were formulated to contain 100% fish meal (FM) protein, 55% FM protein/45% SBM protein, FM-SBM supplemented with 1% GOS, and a combination of 1% yeast and 0.1% β-glucan, respectively. Each diet was fed for 12 weeks to three groups of 30 striped catfish fingerlings (average weight 16.45?±?0.07 g) maintained in circular fiberglass tanks (600 l). Growth, feed utilization, and muscle protein composition of fish improved significantly after supplementation with either GOS or YβG compared to the unsupplemented SBM diet, but were similar to those of fish fed the FM diet. Nutrient digestibility, digestive enzyme activities, villi and microvilli length were significantly increased in fish fed the supplemented SBM diets. The gut microbiota ranking profile showed that supplementing the SBM diet with YβG and GOS gave a ranking of Verrucomicrobia, Spirochaetes, Bacteriodetes, and Actinobacteria phyla similar to that of the FM diet. Thus, diet containing 45% protein from soybean supplemented with either GOS or YβG can be recommended to improve the growth and digestive performance of striped catfish.     

Effect of dietary microbial phytase supplementation on growth performance, nutrient utilization, body compositions and haemato-biochemical profiles of Cyprinus carpio (L.) fingerlings fed soyprotein-based diet

An 8‐week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of microbial phytase on growth, nutrient utilization, haemato‐biochemical status and body compositions in common carp, Cyprinus carpio (L.) fingerlings (average weight 6.66 ± 0.08 g). The aim of experiment was also to determine whether dicalcium phosphates (DCP), tracemineral premix and lysine and methionine supplemental levels in carp diet could be reduced if microbial phytase was supplemented. Control diet (diet 1) supplemented with DCP, tracemineral premix and lysine and methionine without microbial phytase supplementation. Four experimental diets were formulated with reduction of either dietary DCP or trace minerals or lysine and methionine or all four supplementation levels by 100% of control diet without microbial phytase supplementation (diet 2, 3, 4 and 5 respectively). Another two experimental diets were formulated with reduction of all dietary DCP, trace minerals, lysine and methionine supplementation levels by 0 and 100% of control diet with dietary microbial phytase supplementation at 500 FTU kg⁻¹ diet (diet 6 and 7 respectively). After acclimation of fish for 2 weeks, 20 fish were randomly stocked into triplicate tanks for each of seven treatments (T₀, T₁, T₂, T₃, T₄, T₅ and T₆ for diet 1, 2, 3, 4, 5, 6 and 7 respectively) and fed with respective diet to apparent satiation. Results indicated that phytase was effective in releasing most of the phytate bound proteins, amino acids and minerals for optimum utilization and performance. Results also suggested that DCP, trace minerals and lysine and methionine supplementation level could be replaced by microbial phytase supplementation at 500 FTU kg⁻¹ in soybean‐based common carp diets without altering the optimum performance of fish. Optimum replacement level of dietary DCP, trace minerals and lysine and methionine with phytase supplementation at 500 FTU kg⁻¹ soybean‐based carp diet needs to be standardized in further investigations.     

Effects of guanidinoacetic acid supplementation in all‐plant protein diets on growth,antioxidant capacity and muscle energy metabolism of bullfrog Rana (Lithobates) catesbeiana

Effects of guanidinoacetic acid (GAA) supplementation in all‐plant protein diets were evaluated on growth, antioxidant capacity and muscle energy metabolism of Rana (Lithobates) catesbeiana. Six diets were prepared: a basal fish meal diet (FM), an all soybean meal diet (SM) and four GAA‐supplemented diets by adding 0.2, 0.4, 0.6 and 0.8 g GAA/kg to the SM diet (GAA2, GAA4, GAA6 and GAA8 diets). Triplicate groups of bullfrog (45 ± 0.2 g) were fed the diets to apparent satiation for 8 weeks. Total substitution of FM with SM led to significantly (p < .05) reduced growth and feed utilization. Adding 0.4 g GAA/kg to the SM diet significantly improved growth performance, and the values were comparable to those of FM group. SM and GAA2 groups showed drastically lower serum total antioxidant capacity than FM, GAA4 and GAA6 groups. Also, SM and GAA2 groups showed significantly lower catalase activity than FM and GAA8 groups. A remarkable increase in serum malondialdehyde concentration was detected in SM and GAA2 groups. FM and GAA6 groups exhibited significantly higher serum creatinine concentration than other groups. Muscle creatine kinase activity and glycogen content were significantly decreased in SM group and application of 0.4–0.6 g GAA/kg significantly improved their values. GAA4 group showed significantly lower pyruvate kinase activity than FM and GAA6 groups. Also, GAA2 and GAA4 groups had significantly lower succinate dehydrogenase (SDH) activity than other treatments. These findings show that supplementing 0.4 g/kg GAA to SM‐based diets improves growth, antioxidant capacity and muscle energy metabolism.