Effects of replacing fish meal with soybean meal and peanut meal on growth,feed utilization and haemolymph indexes for juvenile white shrimp Litopenaeus vannamei,Boone

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal (FM) with soybean meal (SBM) and peanut meal (PM) on growth, feed utilization, body composition and haemolymph indexes of juvenile white shrimp Litopenaeus vannamei, Boone. Five diets were formulated: a control diet (FM30) containing 30% fish meal and four other diets (FM20, FM15, FM10 and FM5) in which protein from fish meal was substituted by protein from SBM and PM. The dietary amino acids of diets FM20, FM15, FM10 and FM5 were equal to those of the diet FM30 by adding crystalline amino acids (lysine and methionine). Each diet was randomly assigned to triplicate groups of 30 shrimps (initial weight = 0.48 g), each three times daily. The results indicated that shrimp fed the diets FM15, FM10 and FM5 had poor growth performance and feed utilization compared with shrimp fed the control diet. No difference was observed in feed intake, survival and body composition among dietary treatments. The plasma total cholesterol level of shrimp and the digestibility of dry matter, protein and energy contained in the diets decreased significantly with increasing PM and SBM inclusion levels. Results of this study suggested that fish meal can be reduced from 300 to 200 g kg^?1 when replaced by a mixture of SBM and PM.     

Using stable isotope analysis to assess the relationship among dietary protein sources,growth, nutrient turnover and incorporation in Nile tilapia (Oreochromis niloticus)

Nile tilapia (1.20 g) were fed for 56 days in five treatments (FM100 containing only fish meal [FM] as a protein source; soybean meal (SBM) replace 25%, 50%, 75% and 100% of FM protein in the diets of FM75, FM50, FM25 and FM0, respectively) to assess the effects of dietary protein sources on growth, turnover half‐life of nitrogen and carbon stable isotopes (δ¹³C and δ¹⁵N) in muscle, isotope discrimination factors (Δ¹⁵N and Δ¹³C), and the relative contribution of protein sources to muscle growth. Results showed that the final body weight, weight gain and specific growth rate of fish fed diet FM25 were significantly higher than other treatments (p < .05). By day 35, fish under all treatments reached isotopic equilibrium, and the equilibrium values consistently increase as a function of stable isotope values in diets. Growth accounted for most isotopic changes in muscle and resulted in significantly shorter half‐lives of nitrogen and carbon in FM25 (p < .05). The Δ¹⁵N of FM25 and Δ¹³C of FM0 were significantly lower than other treatments (p < .05). The proportional contributions of SBM protein were significantly higher than their respective levels in FM75 and FM25 (p < .05), indicating a preferential incorporation of nitrogen from the SBM in muscle tissue.     

Apparent Digestibility Coefficients and Amino Acid Availability of Cricket Meal,Gryllus bimaculatus,and Fishmeal in African Catfish,Clarias gariepinus,Diet

A study was conducted on African catfish, Clarias gariepinus, to examine the apparent digestibility coefficient (ADC) of protein, dry matter, lipid, and energy, and the apparent availability coefficient (AAC) of essential amino acid (EAA) for a cricket meal (CM) diet, Gryllus bimaculatus, and fishmeal (FM). Both diets consisted of 30% isonitrogenous levels with a 70:30 ratio of basal diet to test ingredient. Chromic oxide (0.5%) was added to the diet as an inert marker. The ADCs of crude protein (CP) in CM (81.21%), lipid (89.82%), gross energy (64.42%), and dry matter (73.97%) was significantly higher (P < 0.05) than the value of CP (78.22%), lipid (82.03%), gross energy (56.52%), and dry matter (62.26%) in FM. All EAAs were present in both diets. The AACs for both diets ranged from 0.906 to 0.961 and 0.812 to 0.938 for the CM and FM diets, respectively. The growth performance of fish fed with CM exhibited significantly higher (P < 0.05) weight gain, feed conversion ratio, and protein efficiency ratio compared with FM. Overall, the results suggest that CM could be included in the African catfish diet without affecting their nutrient and amino acid digestibility as well as growth performance.     

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.     

The effect of dietary cricket meal (<Emphasis Type="Italic">Gryllus bimaculatus</Emphasis>) on growth performance,antioxidant enzyme activities,and haematological response of African catfish (<Emphasis Type="Italic">Clarias gariepinus</Emphasis>)

This study was conducted to investigate the growth performance, biomarkers of oxidative stress, catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) as well as the haematological response of African catfish after being fed with fish feed containing different levels of cricket meal. The juvenile fish were assigned to three different treatments with isonitrogenous (35 %) and isoenergetic (19 kJ g^?1) diets containing 100 % cricket meal (100 % CM), 75 % cricket meal (75 % CM), and 100 % fishmeal (100 % FM) as control groups for 7 weeks. The results indicated that a diet containing 100 % CM and 75 % CM improved growth performance in terms of body weight gain and specific growth rate, when compared to 100 % FM. The feed conversion ratio (FCR) and protein efficiency ratio (PER) did not differ significantly between all diets, but reduced FCR and increased PER were observed with a higher inclusion of cricket meal. A haematological examination of fish demonstrated no significant difference of red blood cells in all diets and white blood cells showed a significantly higher value in fishmeal-fed fish. On the other hand, haemoglobin and haematocrit significantly increased with increasing amounts of cricket meal in the diet. Antioxidant activity of CAT was higher in the 100 % CM group compared to fish fed other diets, whereas GST and SOD showed increasing trends with a higher incorporation of cricket, although insignificant differences were observed between all diets. These results suggest that cricket meal could be an alternative to fishmeal as a protein source in the African catfish diet.     

Growth performance and TOR pathway gene expression of juvenile blunt snout bream,Megalobrama amblycephala,fed with diets replacing fish meal with cottonseed meal

A 16‐week feeding trial was conducted to assess the effects of replacing fish meal (FM) with cottonseed meal (CM) on the growth performance, feed utilization, plasma biochemical composition and target of rapamycin (TOR) pathway gene expression of juvenile blunt snout bream (Megalobrama amblycephala). Five isonitrogenous (36% crude protein) and isoenergetic (16 MJ kg^?1) diets with graded replacing levels of CM (replacing 0, 25, 50, 75 and 100% FM with CM) and similar lysine and methionine concentrations were fed to triplicate groups of fish. Results revealed that specific growth rate (SGR), feed intake and protein efficiency ratio (PER) of group fed with diets replacing FM with CM up to 50% were significantly higher than others (P < 0.05). However, final body weight and feed conversion ratio (FCR) remained similar up to 25% and thereafter significantly decreased and increased, respectively, as the replacement level increased (P < 0.05). Replacement levels significantly decreased hepatosomatic index and viscerosomatic index (P < 0.05), but did not significantly affect condition factor and whole body compositions. Free gossypol mainly accumulated in liver and significantly increased in diets CM75 and CM100 than CM0 (P < 0.05). Replacement significantly influenced plasma urea contents (P < 0.05). Meanwhile, increasing replacement of FM with CM in diets increased insulin‐like growth factor I (IGF‐1) gene expression in liver of blunt snout bream. Target of rapamycin (TOR) gene expression in diet CM100 was significantly lower than that in diets CM0 and CM75, while the eukaryotic translation initiation factor 4E‐binding protein 2 (4E‐BP2) gene expression was not affected by the replacement level of CM in diets. Therefore, based on final body weight and FCR, it suggested that up to 25% of FM (150 g kg^?1 in basal diet) could be replaced by CM in diets, which was 112.5 g kg^?1 FM and 192.9 g kg^?1 CM, for juvenile blunt snout bream.     

Effects of lysine and methionine supplementation on growth,body composition and digestive function of grass carp (Ctenopharyngodon idella) fed plant protein diets using high‐level canola meal

A 76‐day feeding trial was carried out to evaluate the effects of Lysine and Methionine supplementation on growth and digestive capacity of grass carp (Ctenopharyngodon idella) fed plant protein diets using high‐level canola meal (CM). Fish with initial average weight 103.9 ± 0.6 g were fed three extruded diets. Fish meal (FM) diet was formulated as the normal control with 40 g kg^?1 FM and 300 g kg^?1 CM; CM diet was prepared by replacing all FM with CM (total 340 g kg^?1) without Lys or Met supplementation; CM supplement (CMS) diet was similar to CM diet but was supplemented with essential amino acids (EAA) to ensure the levels of Lys and Met similar to those in the FM diet. Feed intake, feed efficiency and specific growth rate of the grass carp fed CMS and FM diets were similar (P > 0.05), but higher than those of the grass carp fed CM diet (P < 0.05). The hepatosomatic index, relative gut length, intestosomatic index and intestinal folds height were significantly improved in fish fed FM and CMS diets as compared to CM diet (P < 0.05). Lower activities of trypsin, lipase and amylase in hepatopancreas were observed in fish fed CM diet (P < 0.05). Three hundred and forty gram per kilogram CM without Lys or Met supplementation significantly decreased trypsin, lipase and amylase mRNA levels in hepatopancreas (P < 0.05). These results indicated that the high supply of CM (340 g kg^?1) in plant protein (200 g kg^?1 soybean meal and 100 g kg^?1 cottonseed meal) diets decreased digestive ability through decreasing digestive enzyme activities and enzyme gene's expressions of grass carp, and these side effects can be reversed by supplementing Lys and Met. Therefore, CM could be high level used in a plant protein blend‐based extruded diet for grass carp as long as EAA were supplemented.     

Effect of fish meal replacement by Chlorella meal with dietary cellulase addition on growth performance,digestive enzymatic activities,histology and myogenic genes’ expression for crucian carp Carassius auratus

This study was conducted to investigate the effects of fish meal (FM) replacement by Chlorella meal (CM) with dietary cellulase supplementation on growth performance, digestive enzymatic activities, histology and myogenic genes’ expression in crucian carp Carassius auratus (initial body weight: 2.90 ± 0.02 g, mean ± SEM). Six isonitrogenous diets were formulated at two cellulase levels (0 and 2 g kg^?1). At each cellulase level, CM was added at three levels of 0, 533.1 and 710.8 g kg^?1 to substitute 0, 75 and 100% of dietary FM respectively. Each experimental diet was randomly assigned to triplicate groups with 25 juvenile fish per fibreglass tank for 8 weeks. Dietary CM substitution significantly increased growth, feed utilization, amylase activity and the expression of Myod, Mrf4 and Myf5, but reduced the Myog expression. Dietary cellulase addition increased hepatosomatic and viscerosomatic index, lipase activity and the expression of Mrf4, but reduced trypsin activity and the expression of Myog and Myf5. Dietary CM substitution enlarged the cell size and also caused some karyopyknosis in liver. Our results showed that CM could totally replace FM in diets; dietary cellulase supplementation at the level of 2 g kg^?1 played a subtle role in improving growth and feed utilization for crucian carp.     

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.     

Evaluation of soybean meal in the formulated diets for juvenile Pangasianodon hypophthalmus (Sauvage, 1878)

The influence of soybean meal (SBM) on the growth and feed utilization of juvenile sutchi catfish (Pangasianodon hypophthalmus, Sauvage, 1878) was investigated. Eight isonitrogenous (300 g kg^?1 CP) and isoenergetic (18 MJ kg^?1) diets were formulated incorporating Argentine SBM to replace fish meal at 0, 150, 300, 450, 600, 750, 900 and 1000 g kg^?1 dietary protein. Each diet was fed to three replicate groups of fish with an initial weight 6.0–6.2 g for twelve weeks. Growth performance decreased, and feed utilization was worsened with the increase in SBM inclusion in the diets. Final weight and relative growth rate (RGR) of fish fed control diet (0 SBM) were significantly higher than those fed test diets (P < 0.05). However, there were no significant differences in the final weight and RGR between the fish fed on 15 SBM, 30 SBM, 45 SBM and 60 SBM diets. Specific growth rate of fish fed 0 SBM, 15 SBM, 30 SBM and 45 SBM diets was significantly higher than those fed other diets. Feed conversion ratio of fish fed 0 SBM, 15 SBM, 30 SBM, 45 SBM and 60 SBM diets was significantly lower than those fed other diets (P < 0.05). The dry matter and protein digestibility were lesser in all the diets in comparison with the control diet. Hepatosomatic index and viscerosomatic index increased with increasing SBM in diet. This present trial indicated that fish meal can be replaced by SBM in the diet of juvenile sutchi catfish only up to 45% of fish meal protein without any adverse effect on growth, feed utilization and body composition.     

Growth and body composition of rohu (Labeo rohita) fed diets containing oilseed meals: partial or total replacement of fish meal with soybean meal

A 56‐day feeding trial was conducted to evaluate growth, feed utilization and body composition of fingerling rohu, Labeo rohita (4.5 ± 0.2 cm; 2.58 ± 0.04 g), fed five isonitrogenous (350 g kg^?1 crude protein) and isoenergetic (15.7 kJ g^?1 metabolizable energy) diets in which the main protein contributors were: diet I, fish meal (FM); diet II, soybean meal (SBM); diet III, groundnut meal (GNM); diet IV, equal amounts of SBM, GNM and canola meal (CM); diet V, equal amounts of FM, SBM, GNM and CM. Fish were stocked in triplicate groups of 25 fish held in 70 L flow‐through tanks (water volume 55 L) and fed twice daily (0900 and 1700 hrs) to apparent satiation. Fish fed diet I exhibited the highest (P < 0.05) values for live weight gain and specific growth rate (% per day). Feed conversion and protein efficiency ratio were better (P < 0.05) in fish‐fed diets I and II. Fish‐fed diet II exhibited lower (P < 0.05) fat and ash contents in carcass. Based on these findings, a 70‐day trial (Experiment II) was conducted with six diets fed under the same conditions where FM was incrementally replaced with SBM. Fingerling L. rohita (6.7 ± 0.4 cm; 4.07 ± 0.02 g) were used for the study. Crystalline l ‐methionine was added to diets containing more than 250 g kg^?1 SBM. This second study showed no significant (P > 0.05) variation in growth, feed utilization and carcass composition for fish fed the different diets. In conclusion, SBM was more effective than GNM or CM, as FM was replaced in feeds for fingerling L. rohita and could completely replace FM when supplemented with methionine and fortified with minerals under the conditions of this study.     

Effect of totally or partially replacing fish meal by alternative protein sources on growth of African catfish Clarias gariepinus (Burchell, 1822) reared in concrete tanks

A 12‐week feeding trial was carried out in concrete tanks to examine complete and partial replacement (75%) of fish meal (FM) with poultry by‐product meal (PBM), meat and bone meal (MBM) and soybean meal (SBM) in practical feeds for African catfish Clarias gariepinus. Triplicate groups of fish (initial body weight ranged from 90.33 to 93.93 g fish⁻¹) were fed seven isonitrogenous and isocaloric diets of 20% digestible protein and 300 kcal 100 g⁻¹ of digestible energy. The control contained 25% herring meal, whereas in the other six diets, PBM, MBM and SBM replaced 75% or 100% of the FM. Final body weight (FBW) and specific growth rate (SGR) of the fish fed diets containing PBM (75% and 100%), SBM (75% and 100%) and MBM (75%) were all higher, but not significantly different than those for fish fed the control diet. Replacing 100% of the FM by MBM significantly lowered FBW and SGR. Concerning whole body composition, there were no significant differences in ash and gross energy content of whole‐body among fish; fish fed diets containing PBM‐100% recorded significantly lower protein content compared with the control diet, while fish fed diet SBM‐100% recorded significantly lower moisture content compared with the control diet. Also fish fed diets SBM‐100% and PBM‐75% recorded higher lipid and gross energy contents compared with the control diet. The study revealed that satisfactory growth and feed utilization responses could be achieved through the replacement of FM by PBM, SBM and MBM in the diet of African catfish.     

Partial or total replacement of fish meal by local agricultural by‐products in diets of juvenile African catfish (Clarias gariepinus): growth performance,feed efficiency and digestibility

The study was undertaken to evaluate the growth performance and feed utilization of African catfish, Clarias gariepinus, fed six diets (D) in which fishmeal (FM) was gradually replaced by a mixture of local plant by‐products. In diets 1 and 2, FM (250 g kg^?1) was replaced by sunflower oil cake (SFOC). In diets 3 and 4, FM (250 and 150 g kg^?1, respectively) was replaced by SFOC and bean meal (BM) while FM was totally substituted by a mixture of groundnut oil cake (GOC), BM and SFOC in diets 5 and 6. Sunflower oil cake was cooked, soaked or dehulled in order to determine the appropriate processing techniques for improving the SFOC nutritive value and to evaluate the apparent digestibility coefficient (ADC) values of the alternative diets. No significant differences were observed for daily feed intake, weight gain, specific growth rate (SGR) and feed efficiency (FE) among fish fed D1, D2, D3 (250 g kg^?1 FM), D4 (150 g kg^?1 FM) and D6 (0 g kg^?1 FM). The highest SGR (3.2% per day) and FE (1.2) were achieved in fish fed D3, and the lowest in fish fed D5 (0% FM), suggesting a maximum acceptable dietary concentration of hulled SFOC below 250 g kg^?1 in African catfish juveniles. Protein efficiency ratio ranged from 2.2 to 3.2 for all dietary treatments and was positively influenced by FM inclusion. African catfish were able to digest plant protein very efficiently in all diets tested. ADC of protein ranged from 88.6 to 89.5%, while ADC of energy was relatively low for diets containing hulled sunflower oilcake (71–74%) and high when sunflower oilcake was dehulled (78.6–81.3%). Similarly, ADC of dry matter was higher when sunflower was dehulled (72.1%) when compared with crude SFOC (60.5%). Soaking increased ADC values for neutral detergent fibre (NDF), dry matter, energy, protein and amino acids (AA). There were no significant differences in protein ADCs (88–90%) with increased levels of dietary vegetable ingredients. Both soaking and dehulling of sunflower before incorporation helped in the reduction of NDF, antitrypsin and tannins. Digestibility of all AA was generally high, greater than 90% for both indispensable and non‐indispensable AA. Based on the data obtained, it was possible to totally replace menhaden fish meal with a mixture of vegetable proteins (72% of total dietary protein) when diets contained a relatively low percentage of animal protein (28% based on blood meal and chicken viscera meal) without negative effects.     

Effects of Dietary Supplements on Growth Performance and Phosphorus Waste Production of Australian Catfish,Tandanus tandanus,Fed with Diets Containing Soybean Meal as Fishmeal Replacement

Effects of dietary phytase, amino acid (AA), and inorganic phosphorus (P) in soybean meal (SBM) diets on the growth, feed utilization, and P waste of Australian catfish, Tandanus tandanus, were evaluated. In Experiment 1, SBM replaced 30% of fishmeal (FM) protein in the four test diets, supplemented with phytase (1000–3000 FTU/kg). In Experiment 2, SBM replaced 45% of FM protein in the four test diets, supplemented with phytase, AAs, inorganic P, or their combinations. Inclusion of 3000 FTU/kg significantly improved growth performance and feed utilization of catfish. Ortho‐P waste was significantly lower in fish fed with SBM diets. At 30% FM protein replacement, dietary SBM did not reduce the total P waste of catfish while dietary phytase significantly did. At 45% FM protein replacement, phytase alone did not significantly improve the growth and feed utilization of catfish fed with SBM diets while significantly better results were obtained when both phytase and AAs were supplemented. Dietary inclusion of inorganic P significantly decreased P utilization and increased P waste of the fish. Dietary phytase significantly improved P utilization of catfish in both experiments.     

Evaluation of feed utilization and growth performance of juvenile striped catfish Pangasianodon hypophthalmus fed diets with varying inclusion levels of corn gluten meal

A nutrition trial with striped catfish (Pangasianodon hypophthalmus) juveniles was undertaken to evaluate the effect of replacing dietary fishmeal (FM) protein with corn gluten meal (CGM). A diet with FM as the main protein source was used as the control diet (FM). Five experimental diets (approximately 320 g kg^?1 crude protein) were formulated to progressively replace 20% (CGM20), 40% (CGM40), 60% (CGM60), 80% (CGM80) and 100% (CGM100) of FM protein. Fifteen fish per tank (initial weight 11.2 ± 0.6 g) were randomly distributed into 18 80‐litre fibreglass tanks connected to a closed recirculation system (temperature 30.3 ± 1.0 °C). The diets were tested in triplicate for 12 weeks. The final weight and specific growth rate (SGR) of fish fed diets CGM20, CGM40 and CGM60 were not significantly different compared to fish fed the FM diet. Feed intake (FI) tended to decrease with increasing dietary CGM level. Striped catfish fed FM, CGM20 and CGM40 had significantly lower feed conversion ratio (FCR) compared with fish fed CGM80 and CGM100 (P < 0.05). The protein efficiency ratio (PER) of fish fed the CGM80 and CGM100 diets was significantly lower than those of all other treatments (P < 0.05). Total ammonia‐nitrogen (TAN) excretion increased with elevated dietary CGM inclusion. The viscerosomatic index (VSI) of fish fed the CGM80 and CGM100 diets were significantly higher (P < 0.05) than those of fish fed the other treatments. The crude lipid content in the final body composition of the striped catfish was elevated significantly with increasing dietary CGM levels. Fish fed the CGM80 and CGM100 diets displayed haematocrit levels significantly lower (P < 0.05) than those fed the other diets. The haemoglobin content in fish was significantly higher in fish fed CGM20 and lower at CGM100 compared to fish fed the FM diet. The results of the present trial indicated that the optimum level of FM protein replacement with CGM determined by quadratic regression analysis was 25.1% on the basis of maximum SGR.     

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.     

Evaluation of Low‐protein Alternative Diets for Pond‐raised Hybrid Catfish,Ictalurus punctatus × Ictalurus furcatus

A study was conducted to evaluate low‐protein traditional or alternative diets for pond‐raised hybrid catfish, Ictalurus punctatus × Ictalurus furcatus. Three 24% protein diets containing decreasing levels of soybean meal (30, 20, and 15%) and increasing levels of cottonseed meal and corn germ meal were compared with a 28% protein control diet. Hybrid catfish fingerlings (mean initial weight = 71 g/fish) were stocked into 20 earthen ponds (0.04 ha) at a density of 14,826 fish/ha with five ponds per dietary treatment. Fish were fed once daily to apparent satiation for a 191‐d growing season. There were no significant differences in total diet fed, net yield, weight gain, feed conversion ratio (FCR), survival, or fillet proximate nutrient composition among dietary treatments (P ≥ 0.10). However, regression analysis showed for fish fed 24% protein diets there was a linear increase in FCR as soybean meal levels decreased (P = 0.06). Compared with fish fed the 28% protein control diet, fish fed 24% protein diets had lower carcass and fillet yield. Results demonstrate a 24% protein alternative diet containing 20% soybean meal may be substituted for 28% protein diets for hybrid catfish during food fish production.     

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.     

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).