Effect of replacing fishmeal and oil with simple or complex mixtures of vegetable ingredients in diets fed to Nile tilapia (Oreochromis niloticus)

The effect of replacing fishmeal with simple or complex mixtures of plant proteins in tilapia diets was examined. Diet formulations were arranged in a 2 × 4 factorial design with two types of plant protein mixtures used to replace fishmeal (simple: soybean meal and maize gluten meal or complex: soybean meal, maize gluten meal, dehulled flax, pea protein concentrate and canola protein concentrate) and four levels of protein originating from fishmeal (1000 g kg^?1, 670 g kg^?1, 330 g kg^?1 and 0 g kg^?1). Diets contained equal digestible protein (380 g kg^?1) and digestible energy (17.6 MJ kg^?1). The average daily gains, specific growth rates and feed efficiencies of fish fed diets with 0 g kg^?1 fishmeal were significantly lower than fish fed diets with the 330 g kg^?1, 670 g kg^?1 or 1000 g kg^?1 fishmeal levels. Fish fed the complex diets had significantly higher average daily gains, specific growth rates, feed : gain ratios and protein efficiency ratios than those fed the simple diets. Intestinal villus length decreased with decreasing levels of fishmeal and increased with increased diet complexity but the effects were not significant. Replacement of fishmeal with a complex mixture of plant ingredients may allow a greater replacement of fishmeal in diets fed to Nile tilapia.     

Estimating digestible protein requirements of silver perch, Bidyanus bidyanus Mitchell

In this study, we estimated requirements for digestible protein, using intact protein sources, at one digestible energy content. Using digestibility data for silver perch (Bidyanus bidyanus Mitchell) for a large number of ingredients, we formulated a ‘summit’ diet to contain between 1.4 and 1.8 times the ‘expected requirements’ for digestible essential amino acids (based on requirements for channel catfish, Ictalurus punctatus Rafinesque). A ‘diluent’ diet was formulated to contain 0.4–0.5 times the expected requirements of digestible essential amino acids. Both ‘summit’ and ‘diluent’ diets contained similar digestible energy (14.7 MJ digestible energy kg^?1 for the summit and 13.4 MJ digestible energy kg^?1 for the diluent). Six diets were prepared with the following amounts of summit–diluent diets: 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. A practical diet widely used by commercial farmers was also included as a control. Ten juvenile fish (2.1–2.6 g) were stocked into each experimental 70‐L acrylic aquarium, and each dietary treatment was randomly assigned to five replicate aquaria. Fish were fed twice daily to apparent satiation for 54 days. Final individual fish weight ranged from 4–15.5 g. Results were analysed using intersecting linear regression analysis. The optimum digestible dietary protein for diets with 13.4–14.7 MJ digestible energy kg^?1, after which protein deposition did not increase significantly, was 28%. Although this study did not determine requirements for individual amino acids, for diets with the digestible energy content used here, requirements for individual amino acids obviously did not exceed the content in the 28% protein diet. These contents are useful as an estimate of ‘recommended levels’ for silver perch diets with 13.4–14.7 MJ digestible energy kg^?1. The proximate composition of fish was affected by diet. Whole body protein and moisture increased, whereas lipid content decreased with increasing dietary protein content (and increasing protein–energy ratio and decreasing lipid). Fish size was also affected by diet; however, the changes in whole carcass proximate composition also occurred for fish fed diets 60:40, 80:20 and the summit diet which were a similar final weight.     

The effects of dietary digestible protein and digestible energy content on protein retention efficiency of juvenile silver perch Bidyanus bidyanus (Mitchell)

Effects of varying dietary digestible protein (DP) and digestible energy (DE) on protein retention efficiency (PRE), weight gain, protein deposition and carcass composition for silver perch (Bidyanus bidyanus, Mitchell) were studied. Using digestibility data for silver perch, we formulated three series of diets with different DE contents (13, 15 or 17 MJ DE kg^?1). For each series, a ‘summit’ diet containing an excess of protein for silver perch (based on previous research) and a ‘diluent’ diet with only 10–13% DP were formulated. By blending the summit and diluent diets together in different ratios, five diets with different DP contents were produced for each DE series. A commercial diet was also included to give 16 experimental diets in total. Eight juvenile fish (mean initial weight 1.2 g) were stocked into each of 64 × 70‐L acrylic aquaria and then each of the 16 diets was randomly allocated to four replicate aquaria. Tanks were supplied with partially recirculated water (75%) at 25–27°C. Fish were fed restrictively, twice per day, based initially on 3.5% body weight day^?1 with 40% of the ration given at 08:30 hours and 60% given at 15:00 hours for 59 days. Quadratic functions were fitted to each energy series to describe the relationship between DP content of diets and PRE (the asymptote of these functions were used to predict maximum PRE). For low DE (13 MJ kg^?1), mid‐DE (15 MJ kg^?1) and high DE (17 MJ kg^?1), the dietary DP contents to give maximum PRE were 24.7%, 26.1% and 30.1% respectively. Carcass fat decreased with increasing DP and increasing DP:DE ratio. Varying the dietary protein and DE also influenced other indices of fish performance. ‘Optimum’ dietary protein therefore depends on several factors. For fish fed, restrictively, the protein content needed to maximize PRE is lower than the content needed to maximize weight gain or minimize carcass fat. For fish fed to satiation, the lowest protein content for maximum weight gain is lower than for fish fed restrictively.     

Inclusion of rendered animal ingredients as fishmeal substitutes in practical diets for cuneate drum, Nibea miichthioides (Chu, Lo et Wu)

Potential of using rendered animal ingredients, poultry by‐product meal (PM), meat and bone meal (MBM), feather meal (FM) and blood meal (BM) to replace fishmeal in practical diets for cuneate drum Nibea miichthioides (Chu, Lo et Wu) was examined in a net pen experiment. A total of 10 dietary treatments were compared. Nine diets were formulated to contain 363 g kg⁻¹ digestible protein and 14.8 MJ kg⁻¹ digestible energy, and a dietary treatment consisting of raw fish (RF) served as reference. In the formulated diets, the control diet contained 350 g kg⁻¹ herring meal, whereas in the other eight diets, the fishmeal were replaced by MBM (30% fishmeal replacement), PM (50% fishmeal replacement), a blend of PM, MBM, FM and BM (30%, 50% and 80% fishmeal replacement), or a blend of PM, MBM and BM (30%, 50% and 80% fishmeal replacement), respectively. Cuneate drum fingerling (initial body weight 28 g) were fed the test diets for 8 weeks. Specific growth rate (SGR), final body weight (FBW), nitrogen retention efficiency (NRE), condition factor and contents of moisture, crude protein and crude lipid in carcass were not significantly different between fish fed the formulated diets. Fish fed the formulated control diet exhibited lower SGR and FBW, but higher FCR, NRE, hepatosomatic index and crude lipid content in carcass and liver than those of the fish fed the RF. Results of the present study indicate that combination of rendered animal protein ingredients can replace most of the fishmeal in practical diets for cuneate drum.     

Effects of Animal Proteins in Practical Diets on Growth and Economic Performance of Climbing Perch,Anabas testudineus (Bloch)

A ten-week feeding trial was carried out to evaluate animal proteins, either alone or in combination (1:1:1), on the growth performances and economic benefit of climbing perch, Anabas testudineus. Four iso-proteinous (40%) diets were prepared, using fishmeal, protein concentrate, and meat and bone meal as major protein source in diets 1, 2 and 3, respectively, while diet 4 consisted of an equal proportion (1:1:1) of the above protein sources. Triplicate groups of fish (0.53 ± 0.02 g) were randomly stocked in 12 earthen ponds at a stocking density of 40,000 ha^?1. Fish fed diet 4 had significantly (P < 0.05) higher percent weight gain and SGR % per day^?1 compared to the fish fed diets 1, 2, or 3. Significantly higher apparent protein efficiency ratio (1.25) and lower apparent feed conversion ratio (2.00) were also observed in fish fed diet 4. Total yield (1,123 kg ha^?1) and net profit (Tk. 116,569 ha^?1) were also higher in fish fed diet 4. It can be concluded that the combination of fishmeal, protein concentrate, and meat and bone meal is more effective for climbing perch than any of the three protein sources alone.     

Evaluation of fish-meal free diets for rainbow trout, Oncorhynchus mykiss

Eight experimental diets were formulated for rainbow trout using agricultural byproducts as major ingredients. Each experimental diet contained varying amounts of corn grain, corn gluten meal, corn gluten feed and one of the following: 200 g kg^?1 peanut meal, 200 or 400 g kg^?1 soybean meal (SBM), 390 g kg^?1 low-allergen soy flour, 310 g kg^?1 soy protein concentrate, 300 g kg^?1 low-allergen soy protein concentrate or 200 g kg^?1 SBM + 110 g kg^?1 blood meal. One diet contained 200 g kg^?1 SBM and canola oil as the main lipid source. The remaining diets contained 95 g kg^?1 menhaden oil. Fish fed a commercial trout diet exhibited significantly greater weight gain (322%), and a lower feed conversion ratio (0.89) but significantly lower protein efficiency ratio (2.18) than fish fed the experimental diets. Within the experimental diets, fish fed the 400 g kg^?1 soy flour diet and the 400 g kg^?1 soybean meal diet had significantly higher weight gains (276% and 268%) and protein efficiency ratios (2.58 and 2.52), and lower feed conversion ratios (1.02 and 1.03) than fish fed other experimental diets. Fillet flavour varied between treatments. Most notable was the lower fishy flavour and higher chicken flavour of fish fed the diet that contained canola oil rather than menhaden oil. Microscopic evaluation of the liver and five sections of the gastrointestinal tract failed to demonstrate any differences between treatment groups. The ingredient costs of several experimental diets were lower than the estimated cost of a standard commercial trout diet. However, the superior feed conversion ratios of fish fed the control diet resulted in lower feed costs per unit of fish produced.     

Utilization of digestible nitrogen and energy from four agricultural ingredients by juvenile silver perch Bidyanus bidyanus

A comparative slaughter, growth assay was carried out using juvenile silver perch to evaluate different inclusion contents of peanut meal, canola meal, meat meal and dehulled field peas. Each ingredient was combined with a nutritionally balanced basal diet composed mainly of fishmeal (27%), soya bean meal (21%), wheat (28%) and sorghum (11%) such that between 15% and 75% of the basal diet was wholly replaced by the test ingredient. In addition, the basal diet was replaced with 15%, 30% or 45% of an inert filler (diatomaceous earth) in order to compare diets containing test ingredients and the inert filler. Fish were fed respective test diets twice a day for 56 days under a slightly restricted feeding regime (90% of apparent satiation) to negate any palatability problems. Weight gain of silver perch decreased steadily as the basal diet was systematically replaced with diatomaceous earth, confirming the limiting contribution to weight gain from the basal diet under a restricted feeding regime. Silver perch fed diets containing a mixture of the basal diet and either peanut meal, meat meal, canola meal or up to 60% field peas gained more weight than fish fed diets containing similar contents of the inert filler, indicating silver perch were able to utilize these ingredients to support growth. Regression analysis was applied to investigate protein and energy retention and models were fitted with 95% confidence and prediction intervals. Inspection of these relationships indicated various outliers which greatly affected the fitted models. We postulate that these outliers represent test diets which contain ingredients that are poorly utilized, or poorly utilized at particular inclusion contents. Removal of these outliers greatly improved the fit of each model. Using this approach, the predicted digestible protein (DP) content that gave maximum protein deposition in silver perch was 41.1%. The DP requirement for maintenance was 0.61 g DP kg BW^?0.6 day^?1 and the efficiency of DP for growth above maintenance was constant (0.45) after diets containing 45% or more of peanut meal and 75% of field peas were removed from the fitted model. The digestible energy (DE) requirement for maintenance was 36.79 kJ kg BW^?0.6 day^?1 and the efficiency of digestible energy for growth above maintenance was constant (0.68) after diets containing 75% of field peas and 75% of canola were removed from the fitted model. Adherence of other diets containing test ingredients to the slope of each regression suggests that silver perch are capable of utilizing any of the protein sources tested at all but the inclusion contents described above. Confirmation of this approach under different feeding regimes is required.     

Substitution of fish meal by sesame oil cake (Sesamum indicum L.) in the diet of rainbow trout (Oncorhynchus mykiss W.)

The present study evaluated the nutritional value of sesame oil cake (SOC) in rainbow trout fry (initial body weight of 1.42 g) in a growth trial performed for 45 feeding days at 15 ± 1 °C. A series of five isonitrogenous (380 g digestible protein kg^?1 dry matter (DM)) and isoenergetic (18.1 MJ digestible energy kg^?1 DM) diets were formulated in which the digestible SOC protein progressively replaced 0%, 13%, 26%, 39% and 52% of the digestible protein of a high quality fish meal (D0‐D52). Growth rate of fry significantly improved in fish fed SOC diets compared to the fishmeal control diet (D0) whatever the SOC inclusion level. This positive effect on growth was mainly related to a marked improvement of voluntary feed intake. The decrease of feed efficiency observed with increasing SOC was entirely explained by the reduction of DM and energy digestibilities with SOC incorporation. Nitrogen retention efficiency (nitrogen gain/nitrogen intake) was high (40–41%) and significantly reduced only in fish fed D52 (37%). Our results suggest that SOC can be a suitable protein source for a carnivorous fish and replace at least half of the fishmeal protein (without amino acid supplementation) without growth reduction in rainbow trout fry.     

Effects of diets with different plant proteins on the performance of silver perch (Bidyanus bidyanus Mitchell) and on water quality in earthen ponds

As part of a project to develop least‐cost diets with low levels of fish meal, silver perch (Bidyanus bidyanus Mitchell) fingerlings (mean weight, 11.8 g) were stocked at a density of 7500 fish ha⁻¹ into 0.1‐ha earthen ponds and fed one of two diets containing 33% digestible protein, 13 MJ kg⁻¹ digestible energy, similar nutrient specifications, but with different levels of fish meal and plant proteins. The reference diet SP35 had 27% fish meal, 28% wheat, 20% soybean and 11% sorghum, while the diet silver perch least‐cost (SPLC) had 10% fish meal, 20% peanut meal, 19% wheat, 17% lupins, 16% canola, 8% soybean and 5% blood meal; there were three replicate ponds for each diet. Fish were fed a restricted ration up to 5% body weight day⁻¹ and cultured for 10 months. Survival ranged from 85.9% to 94.3% and was not affected by diet. The mean weight (550 g), specific growth rate (SGR; 1.28% day⁻¹), absolute growth rate (AGR; 1.9 g fish⁻¹ day⁻¹) and production rate (4.5 tonnes ha⁻¹ year⁻¹) were significantly higher (P<0.05) and feed conversion ratio (FCR=1.8) was significantly lower for fish fed SP35 compared with fish fed SPLC (413 g, 1.18% day⁻¹, 1.4 g fish⁻¹ day⁻¹, 3.3 tonnes ha⁻¹ year⁻¹, 2.4). From October (spring) to March (autumn), turbidity was significantly lower (P<0.05) in SPLC ponds than in SP35 ponds, and fish were observed avoiding or ingesting and then expelling SPLC pellets. In February and March, infestations of the ectoparasitic copepod Ergasilus sp. were found on silver perch fed SPLC, and there was 5% post‐harvest mortality of these fish. The high inclusion levels of plant proteins, particularly peanut meal and canola in SPLC, may have provided anti‐nutritional factors and/or reduced the palatability and intake of the diet, adversely affecting the performance and health of silver perch, and water quality in the ponds. Our study demonstrates the value of evaluating new aquaculture diets under practical conditions over a complete growing period.     

Replacing fish meal with increasing levels of meat and bone meal,soybean meal and corn gluten meal,in diets of juvenile bluegill,Lepomis macrochirus

A 60‐day study was conducted to determine the response of juvenile bluegill Lepomis macrochirus to seven experimental diets, formulated using a blend of alternative protein sources as a replacement for fish meal. Adequate levels (digestible basis) of energy, protein and amino acids were maintained in diets 1–6, whereas slightly lower protein and energy levels were provided in diet 7. Feed cost per tonne ranged from $ 798.9 (diet 1, 550 g Kg^?1 fish meal) to $ 515.8 (diet 6, 0 g kg^?1 fish meal), or to $ 507.2 (diet 7, 0 g Kg^?1 fish meal). Three commercial diets were included in the study as reference diets: a high‐energy and a low‐energy trout diet, as well as a catfish diet. Quintuplicate bluegill groups (~22 g, n = 10 fish group^?1) were fed the experimental diets twice daily to apparent satiation. No major differences in feed consumption, feed efficiency and growth rates were detected among the bluegill groups fed the experimental diets. Trout diets generally produced higher fish fat deposition, whereas the catfish diet produced a poorer fish growth rate relative to the experimental diets. Under the reported conditions, results indicate diet 6, comprising predominantly soybean meal and porcine meat and bone meal, to be the most economical diet for juvenile bluegill.     

Effect of fishmeal substitution with various animal and/or plant protein sources in the diet of the abalone Haliotis discus hannai Ino

The effect of dietary substitution of animal and/or plant protein sources for fishmeal on the growth and body composition of juvenile abalone was determined. Nine experimental diets in triplicate were prepared: Con, SM, PM, CM, SPM, MB, SM+CM, SM+SPM and CM+SPM diets. A 350 g kg^?1 fishmeal was included in the Con diet, and the whole fishmeal was substituted with a 580 g kg^?1 soybean meal (SM), 335 g kg^?1 poultry meal (PM), 370 g kg^?1 corn gluten meal (CM), 325 g kg^?1 silkworm pupae meal dehydrated (SPM), 590 g kg^?1 meat and bone meal (MB), the combined 290 g kg^?1 soybean meal and 180 g kg^?1 corn gluten meal (SM+CM), 290 g kg^?1 soybean meal and 160 g kg^?1 silkworm pupae meal dehydrated (SM+SPM) and 180 g kg^?1 corn gluten meal and 170 g kg^?1 silkworm pupae meal dehydrated (CM+SPM) diets respectively. All experimental diets were iso‐nitronic and iso‐lipidic. The survival of abalone fed with the SM and SM+SPM diets was higher than that of abalone fed with the CM, SPM, MB and CM+SPM diets. Weight gain of abalone fed with the SM+SPM diet was higher than that of abalone fed with all the other experimental diets, except for that of abalone fed with the SM+CM diet. The combined soybean meal and corn gluten meal (SM+CM) or silkworm pupae meal (SM+SPM) could be replaced with the whole fishmeal in the diet for abalone and improved its performance.     

Evaluation of fisheries by-catch and by-product meals in diets for red drum Sciaenops ocellatus L.

This study evaluated various by‐catch and by‐product meals of marine origin with red drum (Sciaenops ocellatus L.). Four different kinds of by‐catch or by‐product meals [shrimp by‐catch meal from shrimp trawling, Pacific white shrimp (Litopenaeus vannamei (Boone)) processing waste meal, red salmon (Oncorhynchus nerka (Walbaum)) head meal, and Pacific whiting (Merluccius productus (Ayres)) meal] were substituted for Special Select? menhaden fish meal at 33% or 67% of crude protein in diets formulated to contain 40% crude protein, 12% lipid, and 14.6 kJ digestible energy g^?1. Each of these diets and three additional diets consisting of shrimp processing waste meal formulated on a digestible‐protein basis and two Pacific whiting diets containing reduced levels of ash were also evaluated in two 6‐week feeding trials with juvenile red drum (initial weight of 4–5 and 1–2 g fish^?1 in trials 1 and 2). Red drum fed by‐catch meal at either level of substitution performed as well as fish fed the control diet; whereas, fish fed shrimp processing waste meal diets had significantly (P≤0.05) reduced weight gain and feed efficiency ratio values compared with the controls, even when fed on a digestible‐protein basis. The diets containing Pacific whiting at either levels of substitution and regardless of ash level supported similar performance of red drum as those fed the control diet. Fish fed the red salmon head meal diet fared poorly, probably owing to an excessive amount of lipid in the diet that became rancid. Overall, by‐catch meal associated with shrimp trawling and Pacific whiting appear to be suitable protein feedstuffs for red drum.     

Evaluating options for fishmeal replacement in diets for juvenile barramundi (Lates calcarifer)

Two experiments were conducted to examine critical thresholds to fishmeal inclusion in diets for barramundi and also the suitability of a range of different raw materials as alternative protein sources for this species. The first experiment used two diets formulated to the same digestible protein and energy specifications, which were then used to create a series of blended experimental diets that varied in fishmeal content from 0 to 770 g kg^?1. An additional diet containing sodium sulfamerazine was used as a negative control. Feed intake was unaffected with diets containing as little as 11% fishmeal, although broken‐line regression suggests that an inclusion of ～150 g kg^?1 fishmeal is a more likely threshold value. In a second experiment, a further series of diets was formulated for juvenile barramundi according to digestible protein and energy specifications predicted by existing bio‐energetic models. Each of the test raw materials was substituted for fishmeal at either 200 or 300 g kg^?1 (dependent on formulation or extrusion limitations), and two additional diets were included to examine two practical formulations. A diet with only fishmeal as the protein source was included as a reference. Each diet was produced using an APV19 twin‐screw extruder and then vacuum infused with the specified fish oil allocation. Each of the diet pellets produced was also characterized for a range of physical parameters. Fish of an initial weight of 70 ± 0.6 g fish^?1 were randomly allocated across 24 tanks with three replicates per treatment. After 6 weeks, average weight gain across all treatments was 73 ± 12.7 g fish^?1 and feed conversion across all treatments averaged 0.94 ± 0.08 g fish^?1. None of the diets using alternative raw materials had poorer growth or feed conversion than the fishmeal‐based reference diet. The inclusion of either the lupin kernel meals or canola meal significantly improved both weight gain and feed conversion compared to the reference diet. The results from this study demonstrate that there is clear potential to replace the fishmeal content of diets for barramundi without loss of fish performance, up to and including diets with as little as 150 g kg^?1 fishmeal inclusion.     

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.     

The effect of the dietary substitution of fishmeal with tuna by‐product meal on growth,body composition,plasma chemistry and amino acid profiles of juvenile Korean rockfish (Sebastes schlegeli)

The effect of the substitution of fishmeal with tuna by‐product meal (TBM) in the diet of Korean rockfish on growth, body composition, plasma chemistry and amino acid profiles was determined. Nine experimental diets were prepared. The control (Con) diet consisted of 550 g kg^?1 fishmeal. The 10, 20, 30, 40, 60, 80 and 100 % fishmeal diets were substituted with tuna by‐product meal (TBM), referred to as the TBM10, TBM20, TBM30, TBM40, TBM60, TBM80 and TBM100 diets, respectively. Finally, the fishmeal and soybean meal was completely replaced with TBM in the diet TBM100‐S. There was no significant difference in weight gain and SGR of the fish that were fed the TBM40 and Con diets. The feed conversion ratio (FCR) of the fish that were fed the Con, TBM10, TBM20 and TBM30 diets was lower than that of the fish that were fed all of the other diets. The protein efficiency ratio (PER) of fish that were fed the TBM10, TBM20 and TBM300 diets was higher than that of fish that were fed the TBM40, TBM60, TBM80, TBM100 and TBM100‐S diets. It can be concluded that the substitution of fishmeal with up to 40 and 30 % TBM in the diet of juvenile Korean rockfish could be made without exerting a detrimental effect on their growth (SGR) and feed utilization (FCR and PER), respectively.     

Effects of varying dietary compositions using common feed ingredients on growth and feed efficiency of pond‐raised channel catfish Ictalurus punctatus (Rafinesque)

Two experiments were conducted to evaluate various ingredient combinations in a 28% or 32% protein diet for optimum performance of channel catfish Ictalurus punctatus. All diets contained soybean meal and corn, but with or without cottonseed meal, wheat middlings or fish meal (FM). Channel catfish fingerlings were stocked into 0.04 ha earthen ponds at 18 530 fish ha^?1. Fish were fed one of eight diets once daily to apparent satiation for two growing seasons. Results demonstrated that the dietary ingredient composition used had significant effects on fish performance, but magnitude of differences was relatively small. Overall, diets containing FM resulted in greater weight gain (Experiments 1 and 2) and lower feed conversion ratio (Experiment 1) than fish fed all‐plant diets. However, certain combinations of plant ingredients provided the similar fish growth as some diets containing FM. There were no significant differences in weight gain between fish fed soybean meal–corn or soybean meal–corn–wheat middlings‐based diets with cottonseed meal or FM. The use of wheat middlings in the diet had no significant effects on fish production characteristics.     

Comparative nutritional evaluation of raw, methanol extracted residues and methanol extracts of moringa (Moringa oleifera Lam.) leaves on growth performance and feed utilization in Nile tilapia (Oreochromis niloticus L.)

The suitability of raw and methanol‐extracted moringa (Moringa oleifera Lam.) leaf meal to replace 10%, 20% and 30% of the total fishmeal‐based dietary protein in tilapia feeds was tested. Ten isonitrogenous and isocalorific feeds (35% crude protein and 20 MJ kg^?1 gross energy), denoted as diets 1 (fishmeal‐based control), 2, 3, 4 (containing 13%, 27% and 40% raw moringa leaf meal), 5, 6, 7 (containing 11%, 22% and 33% methanol‐extracted moringa leaf meal), and 8, 9, 10 (containing methanol‐soluble extracts of the raw moringa leaf meal at the same level as would have been present in diets 2, 3, 4) were prepared. Forty tilapia (16.7±2.4 g), kept individually, were fed the experimental diets (four fish per treatment) at the rate of 15 g feed per kg metabolic body weight (kg^0.8) per day. A reduction in the growth performance was observed with an increasing level of raw moringa leaf meal (diets 2–4), whereas inclusion of methanol‐extracted leaf meal (diets 5–7) had no significant (P<0.05) effect on the growth performance compared with the control (diet 1). The growth performance of fish fed diets 8–10 containing methanol extracts of the moringa leaf meal were also similar to the control. The chemical composition values of the gained weight showed that lipid accretion decreased with increased inclusion of moringa leaves, and ash content increased. Dietary moringa methanol extracts reduced protein accretion, but had no effects on lipid and ash contents compared with the control. The inclusion of raw, methanol‐extracted residues and methanol extracts of the moringa leaf meal (diets 3 and 4, 5, 6 and 7, and 8 respectively) reduced the plasma cholesterol content significantly. Similarly, a significant reduction in muscle cholesterol was observed in fish fed the diets 4, 8, 9 and 10. It was concluded that the solvent‐extracted moringa leaf meal could replace about 30% of fishmeal from Nile tilapia diets.     

Nutritional assessment of Australian canola meals. II. Evaluation of the influence of the canola oil extraction method on the protein value of canola meals fed to the red seabream (Pagrus auratus, Paulin)

This study examined the biological value of expeller‐ and solvent‐extracted canola meals when included in the diets of juvenile red seabream. Notably, the test and reference diets in this study were prepared to be protein (300 g kg^?1 DM) and energy (16.5 MJ kg^?1 DM) limiting. Test diets were prepared, in which canola meal provided either 20%, 40% or 60% of the total dietary digestible protein. To minimize the influence of compensatory feed intake, all diets were pair‐fed to the fish on restricted basis. Positive and negative controls were also included as treatments in the study to demonstrate that the diets were protein limiting and also to demonstrate the relative value of the highest inclusion levels of each test ingredient. The canola meals, either expeller‐ or solvent‐extracted, were found to be nutritionally useful in diets for red seabream. Both ingredients were of similar value to that of the soybean meal when included on an equivalent digestible protein basis. No significant differences in weight gain, survival, FCR, N retention, energy retention or the apparent biological value of the N content were observed among any of the groups receiving the test or reference diets. A few significant differences were observed among some of the test and reference diets with regard to the apparent biological value of their energy content, although no consistent pattern was evident. The positive control treatment supported significantly superior growth and food utilization by the fish relative to all other treatments. The negative control treatment resulted in significantly poorer growth and food utilization by the fish relative to all other treatments. On a relative basis, there were no declines in fish performance between the highest inclusion levels of the expeller‐ and solvent‐extracted canola meals or the soybean meal. Hence, the fish in this study obtained equivalent nutritional value from these ingredients, on a digestible basis, to that of the fishmeal in the reference diet.     

Apparent digestibility coefficients of several protein sources,and replacement of fishmeal by porcine meal in diets of Japanese seabass,Lateolabrax japonicus,are affected by dietary protein levels

A digestibility and a growth trial were conducted in this study respectively. Firstly, the apparent digestibility coefficients (ADC) of nutrients and energy in meat and bone meal, porcine meal (PM), hydrolysed feather meal, poultry by‐products meal, fishmeal (FM), soybean meal and spray‐dried blood meal were determined. In experiment 2, an 8‐week growth trial was conducted to evaluate the effects of the substitution of FM by PM under the digestible ideal protein concept at two protein levels in the diets of Japanese seabass, Lateolabrax japonicus. A FM‐based control diet (FM diet; FM: 320 g kg^?1, crude protein: 434.9 g kg^?1, crude lipid: 124.6 g kg^?1) and three other diets were formulated to contain 115 g kg^?1 PM and only 160 g kg^?1 FM. Two diets were formulated on a crude protein basis without (PM diet) or with (PMA diet) essential amino acid (EAA) supplementation respectively. A low‐protein diet was designed (LPMA diet, crude protein: 400.9 g kg^?1, crude lipid: 96.3 g kg^?1) with the same level of FM and PM but with the same digestible protein/ digestible energy and EAA profile as the FM diet. The results showed that nitrogen and total amino acid digestibility of the tested ingredients were ranged from 85.6% to 95.5% and from 87.6% to 95.5% respectively. Apparent digestibility coefficients of protein for FM and PM were 91.2% and 95.9% respectively. In the growth trial, the weight gain rate and feed conversion ratio of fish fed the PMA diet did not show a significant difference from those of the control group, but were significantly higher than those of the PM and LPMA groups (P<0.05). Growth was related linearly to lysine and methionine intakes. It was shown that PM could be utilized in the Japanese seabass diet up to 115 g kg^?1 to replace about 160 g kg^?1 of FM protein under an ideal protein profile. Essential amino acid deficiency (diet PM) or a lower protein level despite having an ideal amino acid profile (diet LPMA) could not support the optimal growth of Japanese seabass.     

Growth,nitrogen gain and indispensable amino acid retention of pacu (Piaractus mesopotamicus,Holmberg 1887) fed different brewers yeast (Saccharomyces cerevisiae) levels

A feeding‐and‐digestibility trials were carried out to evaluate the efficacy of replacing fishmeal with brewers yeast Saccharomyces cerevisiae in diets of pacu, Piaractus mesopotamicus, juveniles. The feeding trial was conducted during 54 days with 450 fish (26.6 ± 1.7 g) testing six isonitrogenous (270 g kg^?1 crude protein) and isoenergetic (19 MJ kg^?1 crude energy) diets, with increasing yeast level to replace 0 (control), 30, 35, 50, 70 or 100% of dietary fishmeal. Growth performance and feed utilization increased with increasing dietary yeast level until 50% fishmeal replacement. Protein retention efficiency was higher in fish fed 35 and 50%. Protein digestibility and the fillet hue (the red/green chromaticity) were not significantly different among all treatments. Nitrogen gains were significantly improved in fish fed 35% replacement diet compared to fish fed the control diet. The retentions of indispensable amino acids tended to increase with increasing dietary yeast levels, with maximum retention at 35–50%. On the basis of our results, replacing 50% fishmeal by yeast in pacu diets successfully improved feed efficiency and growth performance, and reduced nitrogen losses, thereby reducing the nitrogen outputs from fish farms.