Partial replacement of soybean meal by sesame meal in diets of juvenile Nile tilapia,Oreochromis niloticus L.

An 8‐week feeding trial was conducted to determine the effects of replacing of soybean meal (SBM) with sesame meal (SM) in the diets of Oreochromis niloticus fingerlings. Seven practical diets (33 g kg^?1 crude protein, 19.2 MJ kg^?1 dry diet) containing substitution levels of 0%, 8%, 16%, 24%, 32%, 40% and 48% SM for SBM protein were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 8.74 ± 0.12 g). The fish survival rate, hepatosomatic index, viscerosomatic index and condition factor were not significantly affected by the contents of SM in the diets (P>0.05). The final body weight, weight gain (WG), specific growth ratio, feed conversion ratio and protein efficiency ratio of the fish fed the diet containing 16% SM were similar (P>0.05) to that of the fish fed the control diet. Except lipid, digestible contents of dry matter, crude protein, ash, gross energy and individual amino acids decreased while phosphorous increased with increasing SM levels. No significant differences were observed in whole‐body dry matter, ash and lipid contents among all the treatments (P>0.05); crude protein contents between fish fed the control diet and a diet containing 24% SM were also not affected significantly (P>0.05), and the phosphorus content was not significantly different when the SM level was increased to 32% (P>0.05). No significant negative differences were observed in the liver composition between fish fed the control diet and the diet containing 24% SM. The most efficient diet in terms of cost per unit WG of fish was obtained in 8% SM dietary substitution, while no significant differences were found among the 0%, 8% and 16% levels. It was indicated that SM can be utilized in the juvenile Nile tilapia diet to replace about 16% of SBM protein without causing negative effects on growth performance, body composition, liver composition and feed utilization.     

Dry whey meal as a protein source in practical diets for Nile tilapia,Oreochromis niloticus fingerlings

ABSTRACT

This study was conducted as a trial of using dry whey meal (DWM) as a substitute for fish meal (FM) in practical diets for Nile tilapia, Oreochromis niloticus. Triplicate fish groups were fed on five isonitrogenous (30.2%) and isolipidic (6.9%) diets. The control diet (D1) used FM as the sole protein source. In the other four diets (D2–D5), FM protein was substituted by 25, 50, 75, or 100% DWM. Fish (3.5 ± 0.1 g) were stocked at a rate of 20 fish per 100-L aquarium and fed one of the tested diets up to satiation twice daily for 12 weeks. Fish growth, feed utilization, protein efficiency ratio, apparent protein utilization, and energy utilization for fish fed DWM diets up to 75% FM (D2–D4) tended to be higher but were not statistically different than the control diet. No significant effect of diet was found in whole-body moisture, crude protein, and total ash contents. Whole-body lipid content in fish fed the 100% DWM (D5) diet was significantly higher than that for fish fed the control diet. The optimal replacement level of FM by DWM was estimated by second-order polynomial regression to be 62.5%.     

Replacement of fish meal with a mixture of different plant protein sources in juvenile Nile tilapia, Oreochromis niloticus (L.) diets

A plant protein mixture (PPM) was tested to replace fish meal (FM) in diets for juvenile Nile tilapia, Oreochromis niloticus. Fish averaging (±SD) 3.7±0.14 g were divided into 15 groups. Three groups were fed each of five isonitrogenous (33.6%) and isocaloric (4.7 kcal g^?1) diets replacing 0%, 25%, 50%, 75% and 100% of the FM protein with similar percentages of PPM (PPM0, PPM25, PPM50, PPM75 or PPM100 respectively). The PPM consisted of 25% soybean meal, 25% cottonseed meal, 25% sunflower meal and 25% linseed meal, and 0.5% of both methionine and lysine were added to each diet except for the control. After 16 weeks of feeding, the fish fed diets PPM75 and PPM100 exhibited growth performance not differing significantly from the fish fed control diet. PPM substitution of up to 75% of the FM protein did not result in differences in the apparent protein digestibility compared with the control, whereas in the PPM100 group digestibility was significantly lower than in the other groups, except for fish fed the PPM75 diet. The incorporation of PPM in diets did not significantly affect whole‐body dry matter, protein, fat or energy compared with the control. The cost–benefit analyses of the test diets indicated that the PPM diets were economically superior to FM. The protein from PPM can completely replace the FM protein in the diets for Nile tilapia, based on the results of this study.     

Effects of partial and complete replacement of soybean meal with cottonseed meal on growth,feed utilization and haematological indexes for mono‐sex male Nile tilapia,Oreochromis niloticus (L.) fingerlings

The main objective of this study was to evaluate the effects of replacing soybean meal (SBM) with cottonseed meal (CSM) on the growth performance, feed utilization and haematological parameters of mono‐sex male Nile tilapia fingerlings. Five isonitrogenous diets (containing 31.82% crude protein) containing graded levels of CSM to replace SBM protein were fed to triplicate groups of fish. The diets were supplemented with lysine so that they were similar to the control diet. After a 14‐week feeding experiment, the results revealed that up to 75% of SBM could be replaced by CSM without causing a significant reduction in growth. Fish fed the diet highest in CSM had a significantly lower protein efficiency ratio and a significantly higher feed conversion ratio than fish fed the other diets. High survival was observed in all the dietary treatments, and no significant difference was observed among treatments. The apparent digestibility coefficients (ADC) of dry matter and phosphorus decreased significantly with an increase in the dietary CSM level, whereas the ADC of lipid was not affected by the dietary treatment. The hepatosomatic index and the condition factor were significantly affected by the replacement of SBM by CSM. No significant differences were detected in the moisture, lipid and ash content in whole body and muscle samples, but protein in whole‐body samples was significantly affected by the CSM levels. Significant differences were found in the haemoglobin, haematocrit, red blood cell and white blood cell contents in fish fed diets with different CSM levels. Therefore, these findings suggest that up to 41.25% CSM can be used to replace 75% of SBM protein in diets for mono‐sex male Nile tilapia fingerlings without any adverse effects on the growth performance, feed utilization, body composition and haematological indexes.     

Potential of the use of peanut (Arachis hypogaea) leaf meal as a partial replacement for fish meal in diets for Nile tilapia (Oreochromis niloticus L.)

The rapid growth of tilapia culture has stimulated the expansion of tilapia feed production and a search for novel protein sources to replace fish meal. Vegetable or plant sources are promising alternatives and legumes are both naturally abundant and high in protein content. A study was carried out to evaluate the effects of replacing the protein from fish meal with peanut ( Arachis hypogaea ) leaf meal (PLM) in diets for male tilapia ( Oreochromis niloticus , initial body weight 75.3 g). Four isonitrogenous (35% CP) and isocaloric (18.834 kJ g⁻¹) diets were prepared to include 0% (CON), 10% (PLM10), 20% (PLM20) and 30% (PLM30) of PLM protein. Average fish weights at the end of the 126-day experiment were not statistically different among the fish fed CON, PLM10 and PLM20 diets. The PLM30 diet produced the poorest growth performance. Organic matter and protein contents of fish were similar in the CON, PLM10 and PLM20 diets. Carcass chemical composition showed a decrease in body fat content as PLM replacement levels increased. The high survival ratio in all dietary groups (>97%) suggests that PLM can be used in O. niloticus feeds for long periods without affecting fish growth performance or health.     

Substitution of fish meal with sunflower seed meal in diets for Nile tilapia (Oreochromis niloticus L.) reared in earthen ponds

This study investigated sunflower seed meal (SSM) as dietary protein replacement of fish meal (FM) for Nile tilapia (Oreochromis niloticus) juveniles (initial mean weight of 19.8 ± 6.3 g) reared in earthen ponds for 210 days. SSM replaced 25%, 50%, 75%, and 100% (i.e., D₂₅, D₅₀, D₇₅, and D₁₀₀, respectively) of FM in an isonitrogenous and isocaloric diet. The optimum FM replacement level of D₂₅ as predicted by the equation y = 177.5 + 26.5x – 7.9x² yielded an optimum weight of about 184 g within 100 days. Thus D₂₅ was the most effective SSM level for Nile tilapia growth in earthen ponds. Fish growth declined as SSM exceeded D₂₅. The length-weight relationship (r ≥ 90%) depicted an isometric fish growth. Nutrient utilization parameters were similar in all the diets except for D₁₀₀. The protein content of fish carcass was highest in the control and D₂₅, while fiber level was highest in D₁₀₀. Amino acids imbalance and high fiber content could have reduced the fish growth at D₅₀, D₇₅, and D₁₀₀.     

Nutritional evaluation of waste date fruit as partial substitute for soybean meal in practical diets of juvenile Nile tilapia, Oreochromis niloticus L.

The potential of waste date meal (WDM; low-quality date palm, Phoenix dactylifera L.) as a carbohydrate source in formulated diets for Nile tilapia was evaluated. Four isocaloric-practical diets (15.7 kJ g⁻¹) were formulated incorporating WDM at 0, 100, 200 and 300 g kg⁻¹ levels as partial substitutes for soybean meal (SBM). These were designated D₀ [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg⁻¹ diet], D₁ (279 g CP and 446 g CHO kg⁻¹ diet), D₂ (207 g CP and 495 g CHO kg⁻¹ diet) and D₃ (175 g CP and 578 g CHO kg⁻¹ diet). Each diet was fed to three replicate groups of 30 fish [20.20 ± 0.09 g (±SE)] for 75 days. No feed-related mortality was observed during the entire experimental period. Final body weight (FBW) and specific growth rate (SGR) in the different treatments were statistically not significantly different ( P  > 0.05). Protein efficiency rate (PER) was lowest in diet D₀ and increased with decrease of SBM content (D₁–D₃). A significant increase in whole body lipid content was recorded in fish fed diets D₂ and D₃. Results showed that WDM could be a substitute for SBM up to 300 g kg⁻¹ in practical Nile tilapia diets without compromising growth.     

Growth, feed utilization and body composition of tilapia (Oreochromis sp.) fed with cottonseed meal-based diets in a recirculating system

The suitability of cottonseed meal (CSM) as a major source of plant protein in feeds for tilapia ( Oreochromis sp.) was tested by examining growth and feed intake, feed digestibility, liver gossypol concentrations, feed utilization, and body mineral composition. Juvenile tilapia at an initial average size of 11.8 ± 1.6 g were divided into triplicate groups per dietary treatment and offered five different formulated diets. In these feeds fish meal (FM) protein was gradually replaced by protein from CSM (0, 25, 50, 75, and 100%; diets 1, 2, 3, 4 and 5, respectively). The experiments were conducted in a recirculation system at a water temperature of 27 ± 1°C in glass aquaria for 16 weeks. Tilapia growth did not differ significantly ( P  > 0.05) with up to 50% substitution of FM with CSM. Fish meal replacement above 50% resulted in significant growth decline with time. Fish fed with 100% FM and diets including 50% CSM had significantly better daily weight gain, daily feed intake and feed efficiency ratio than those fed with 100% CSM. Fish fed with 75% CSM and above had lower concentrations of body iron, calcium and phosphorus than controls (100% FM). Concentrations of total gossypol in diets (ranging from 0.11 to 0.44% in diets 2–5) resulted in proportional increase of total gossypol in fish liver (32.3, 72.3, 99.4 and 132.1 μg g⁻¹ wet weight) in groups fed with diet 2, 3, 4, and 5, respectively. We concluded that CSM can partially replace FM as a main source of protein in feed for tilapia at not more than 50%. The presence of gossypol in CSM was identified as the major limiting factor for acceptance and utilization of CSM-based diets in tilapia farming.     

Salmon testes meal as a functional feed additive in fish meal and plant protein‐based diets for rainbow trout (Oncorhynchus mykiss Walbaum) and Nile tilapia (Oreochromis niloticus L.) fry

Fishery processing by‐products are a large resource from which to produce fishmeal and other products for a variety of uses. In this study, testes meal (TM) produced from pink salmon processing by‐product was evaluated as a functional ingredient in aquafeeds. Nile tilapia and rainbow trout fry were fed five isonitrogenous and isoenergetic experimental diets for 4 and 9 weeks respectively. Two diets were fishmeal‐based (FM) and three were plant protein‐based (PP). Salmon TM was added to the FM and PP diets at 7% to replace 20% of fishmeal protein (FMTM and PPTM respectively). An additional control diet was prepared in which fishmeal was added to the PP diet to supply an equivalent amount of protein as supplied by TM (PPFM). Inclusion of TM in both the FM‐ and PP‐based diets resulted in higher final body weights, although differences were only significant between rainbow trout fed FM or FMTM diets. Similar differences were calculated for other indices of fish performance, e.g. specific growth rate, feed conversion ratio, protein efficiency ratio and protein retention efficiency. Feed intake was significantly higher for fish fed FMTM compared with FM in rainbow trout. For tilapia, final weights were numerically higher, but not significantly different for fish fed diets containing TM compared with non‐TM diets (FM vs. FMTM; PP vs. PPTM). Performance of trout or tilapia fed the PPFM diet did not increase compared with the PP diet. The results indicate that TM addition to both FM and PP diets increased feed intake and also increased metabolic efficiency, demonstrating that TM can be a functional ingredient in aquafeeds.     

Effects of cellulase addition to canola meal in tilapia (Oreochromis niloticus L.) diets

The effects of commercial cellulase enzyme products on the nutritive value of canola meal (CM) were determined in tilapia fry. Nine diets were prepared by adding cellulase enzyme (1–5 g kg^?1) to control diet (containing no canola), low canola (41.7 g kg^?1 CM) and high canola (208.3 g kg^?1 CM). Tilapia fry was fed for 90 days, and growth, feed conversion ratio (FCR), body composition and nutrient digestibility were determined. Fish fed the diets containing the lowest levels of canola meal (41.7 g kg^?1) had similar final weight and FCR relative to the group fed the control diet, and high canola diet showed significantly lower growth than other groups (P < 0.05), irrespective of cellulase enzyme. The addition of canola meal to tilapia diets resulted in lower protein digestibility and cellulose digestibility. There were no significant differences in body compositions in all treatments. Addition of enzymes to canola meal diets had no significant effects on growth performance, body compositions and nutrient digestibility. The results of this study indicate that use in higher level of canola meal in tilapia diet was adversely affected growth parameters and FCR. Adding dietary cellulase enzyme in different rations to diets showed no significant differences in growth parameter.     

Partial substitution of fish meal with soybean and cottonseed meals in diets for African bonytongue,Heterotis niloticus (Cuvier, 1829) fingerlings: effects on growth,feed efficiency and body composition

A feeding trial was conducted to examine the suitability of soybean meal (SBM) and cottonseed meal (CSM) as a partial substitute for the dietary protein supplied by fish meal for H. niloticus fingerlings. Fish were fed with four isonitrogenous (350 g kg^?1 crude protein) and isoenergetic (18.8 kJ g^?1 GE) diets in which fish meal protein was gradually replaced by plant protein from a mixture of SBM and CSM (0%, 25%, 50% and 75% in diets 1, 2, 3 and 4 respectively). Triplicate groups of fingerlings H. niloticus (mean weight of 5 g) were handfed twice daily to apparent satiation for 60 days inside net hapas. Growth performances (SGR varied from 3.09% to 3.16% day^?1) of fingerlings fed diets containing 0%, 25% and 50% plant protein were not significantly different (P>0.05). At 75% fish meal substitution, growth and feed utilization efficiency indicators were significantly reduced (P<0.05). The carcass composition were also significantly (P<0.05) affected by the replacement level of fish meal, except dry matter and ash. Results suggest that the dietary fish meal protein could efficiently be substituted by a mixture of soybean and cottonseed meals up to 50%, without adverse effects on maximal growth in practical diets for H. niloticus fingerlings.     

Effect of using okara meal,a by‐product from soymilk production as a dietary protein source for Nile tilapia (Oreochromis niloticus L.) mono‐sex males

The main objectives of this study was to evaluate the effect of partial and total replacement of fishmeal protein by okara meal (OM) protein in practical diets on growth performance, feed utilization and body composition of Nile tilapia (Oreochromis niloticus L.) mono‐sex males. Fish of an average initial weight of 2.67 ± 0.01 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. Fishmeal protein (18% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of fish meal (FM) by OM on the basis of crude protein was as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D) and 100% (diet E). Diets were fed to fish at a rate of 5%, and then gradually reduced to 4% of the total fish biomass daily, for a period of 12 weeks. The results revealed that the fish fed diets A (100% FM control), B (25% OM), C (50% OM) and D (75% OM) had significantly the best average body weight, weight gain g, specific growth rate (SGR % day^?1), weight gain % and feed intake g fish^?1 compared with diet E (100% OM) which had the lowest values. There were no significant differences (P > 0.05) among all experimental diets and control in terms of feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate %. Whole body protein contents for fish fed diets B, C and D were superior to the control diet. Incorporation of OM in the diets increased significantly whole body fat content. Incorporation of OM in the diets significantly increased apparent digestibility coefficient of crude protein crude fat and energy. Therefore, these findings suggest that up to 75% of FM protein can be replaced by OM protein in Nile tilapia, mono‐sex male diets.     

Effects of low and medium levels of red alga Nori (Porphyra yezoensis Ueda) in the diets on growth,feed utilization and metabolism in intensively fed Nile tilapia,Oreochromis niloticus (L.)

A 10‐week feeding experiment was conducted in a respirometric system to evaluate the suitability of red alga Nori (Porphyra yezoensis) as a partial replacement for fish meal in intensively fed Nile tilapia. Diets were formulated to be iso‐nitrogenous and iso‐energetic and to replace 0%, 15% and 30% fish meal with Nori, P. yezoensis. No statistically significant differences in growth or feed utilization between the control diet and either Nori diet were found. Tilapia fed on Nori 15 increased their body mass by 415%, those fed the control diet by 341% and fish fed Nori 30 by 317% over the experimental period. Nori 15 fed fish showed the best feed utilization, highest metabolic growth rate and significantly lower oxygen consumption rates than the control. Both Nori supplemented groups (Nori 15: 4.1 g O₂ g^?1 protein gain and Nori 30: 3.9 g O₂ g^?1 protein gain) used less oxygen per gram of protein gain compared to fish fed the control diet (5.4 g O₂ g^?1 protein gain). Our results show that a low replacement level (15%) of fish meal with Nori improves growth and feed utilization while oxygen consumption and amount of oxygen consumed per gram protein gain are significantly decreased.     

Complete replacement of fish meal by porcine and poultry by-product meals in practical diets for fingerling Nile tilapia Oreochromis niloticus: digestibility and growth performance

The apparent digestibility coefficients (ADC) of poultry by-product meal-pet food grade (PBM) and porcine meal (PM) were determined for fingerling male Nile tilapia. ADC for protein were 98.1% and 92.3% in PBM and PM, and 87.1% and 79.4% for energy. PBM and PM were then used as complete replacements for fish meal (FM) in practical diets for Nile tilapia formulated to contain equal digestible protein (300 g kg⁻¹) and energy (16.74 MJ per 100 g) on an as-fed basis. Fingerlings (mean initial weight ±SD, 9.5 ± 0.015 g) were fed for 8 weeks on one of the four diets: FM-, PBM- or PM-based and a commercial feed. The ADC for protein in control and PBM diets (89.7% and 87.9%) were significantly higher than those for the control diet (81.96%). Growth performance and feed utilization were statistically similar between fish fed control and PBM diets, whereas the PM diet exhibited significantly lower performance compared with the control. However, the PM diet showed similar results to the commercial reference diet. Survival and feed conversion ratio were not significantly influenced by replacement of FM with either PBM or PM. The results indicated that PBM and PM can effectively replace FM in practical diets for fingerling Nile tilapia.     

Effects of partial and complete replacement of freshwater shrimp meal (Caridinea niloticus Roux) with a mixture of plant protein sources on growth performance of Nile tilapia (Oreochromis niloticus L.) in fertilized ponds

Despite the well‐documented herbivorous food habits, commercial feeds for production of Oreochromis niloticus usually contain between 7% and 15% animal protein. However, animal protein feedstuffs are expensive, hence the need to search for cost‐effective alternatives in plant‐protein sources. Such alternatives are probably more effective in semi‐intensive systems where natural pond food forms part of the diet. This study evaluated the performance of O. niloticus after feeding diets in which fresh shrimp meal (SM) was gradually replaced by a mixture of plant‐protein sources in fertilized ponds. Three isonitronegenous (24% crude protein) diets containing 12 (control), 6% and 0% SM were fed to three groups of O. niloticus in four replicates per group for 250 days. Fish were fed daily at 2% body weight and sampled monthly to monitor growth and make feed adjustments. Growth, yields, survival and feed conversion ratio were not significantly different (P>0.05) among treatments. Growth of males was double that of females, while the sex ratio was skewed towards females. Although complete substitution of SM by plant protein did not affect the growth of tilapia, production cost was reduced by 36%. In conclusion, animal protein is not required in diets for production of O. niloticus in fertilized ponds.     

Evaluation of hydrolysed rubber seed meal as a dietary protein source for Nile tilapia Oreochromis niloticus L.

This study evaluated the use of hydrolysed rubber seed meal as a locally grown alternative feed ingredient to reduce the use of fishmeal within formulated feeds for tilapia. Five experimental diets were prepared by formulating different inclusion levels of hydrolysed rubber seed meal (0%, 25%, 50%, 75% and 100% of plant‐based protein contribution). Dried and defatted rubber seed meal was hydrolysed by adding rumen digesta liquid to the ingredient. For digestibility measurement, chromic oxide was added to each diet as an inert marker. The digestibility trial was conducted over a 14‐day period by collecting faecal matter from the rearing tanks. In addition, a growth trial was conducted over a period of 50 days using four replicates per dietary treatment. In both experiments, all fish were fed three times daily to apparent satiation. At the end of growth trial, the inclusion level of hydrolysed rubber seed meal up to 50% of plant‐based protein contribution did not give any significant difference compared to the control diet in terms of feed efficiency, specific growth rate and protein retention parameters. In the digestibility study, fish fed diets containing hydrolysed rubber seed meal up to a 50% of plant‐based protein inclusion level did not give any significant difference compared to the control diet in terms of protein and dry matter apparent digestibility. Based on the result of this growth and digestibility study, up to a 50% of plant‐based protein contribution of hydrolysed rubber seed meal can be used within formulated tilapia feeds without any adverse effect.     

Dietary taurine enhances growth and feed utilization in larval Nile tilapia (Oreochromis niloticus) fed soybean meal‐based diets

This study was conducted to evaluate the effects of dietary taurine on growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) larvae. Four plant protein‐based, isonitrogenous (400 g kg^?1 protein), isoenergetic (19 MJ kg^?1) diets supplemented with four taurine concentrations (0.0, 5.0, 10.0 and 15.0 g kg^?1; designated as T₀, T_0.5, T₁ and T_1.5, respectively) were prepared. The diets were fed to triplicate groups of fish larvae (0.024 g average body weight), to apparent satiation, three times per day for 60 days. Larval growth rates and feed utilization efficiency were significantly improved with increasing supplemental taurine up to 10 g kg^?1 and decreased with further taurine supplementation. The quadratic regression analyses indicated that the maximum larval performance occurred at about 9.7 g kg^?1 of total dietary taurine. Fish survival was significantly lower at 15 g kg^?1 dietary taurine than at other taurine levels. Body protein significantly increased, while body moisture and ash decreased, with increasing dietary taurine up to 10 g kg^?1 and decreased with further taurine supplementation to 15 g kg^?1. Body lipid was not significantly affected by dietary taurine concentration. A number of body amino acids (tryptophan, arginine, histidine, leucine, isoleucine, valine, alanine, glycine, threonine and taurine) significantly increased with increasing supplemental taurine up to 10 g kg^?1 and then decreased with further increase in dietary taurine levels. The rest of body amino acids were not significantly affected by dietary taurine. The present results suggest that about 9.7 g kg^?1 dietary taurine is required for optimum performance of Nile tilapia larvae fed soybean meal‐based diets.     

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.     

Evaluation of replacing fish meal with corn protein concentrate in Nile tilapia Oreochromis niloticus fingerlings commercial diet

Four isocaloric‐isonitrogenous diets containing 0, 50, 100 and 190 g/kg corn protein concentrate (CPC) as replacement for dietary fish meal were fed to Nile tilapia Oreochromis niloticus fingerlings for 8 weeks. Tilapia growth parameters were not significantly (p > .05) different in fish fed diets with 0, 50 and 100 g/kg CPC and found to be superior compared to those fed on 190 g/kg CPC. Fish dressing ratios and body composition were similar among all treatments. The electron microscope indicated that the stomach size of control fish was slightly smaller and the wall was thinner while the stomach of the fish fed all other levels of CPC undergone a remarkable size increase and their walls were thicker after feeding diets with CPC. Total aerobic bacterial and coliform counts were significantly decreased in fish intestine when fed diets with 100 and 190 g/kg CPC compared with fish fed diets with 0 g/kg or 50 g/kg CPC. This study indicates that it is possible to replace up to 534 g/kg of dietary fish meal in tilapia fingerlings using 100 g/kg of CPC without any negative effect on fish growth and proximate body composition.