Use of salmon by‐product meals as a replacement for anchovy meal in practical diets for the Pacific white shrimp (Litopenaeus vannamei)

A series of trials were conducted with Pacific white shrimp Litopenaeus vannamei, to evaluate the efficiency of two salmon meals as compared to anchovy meal. The basal diet contained 200 g/kg anchovy meal, which was systematically replaced (0%, 50%, 75% and 100%) with salmon meal on an isonitrogenous basis. Another two diets were formulated with a hydrolysed salmon meal to replace 50% and 100% anchovy meal. Each diet was randomly fed to four replicate groups of 25 and 30 shrimp per tank in clear (indoor) and green (outdoor) water trials, respectively. The results showed that growth performance and feed conversion ratio were not statistically different when salmon meal replaced anchovy meal in both trials. However, when hydrolysed salmon meal was used to replace 100% of the anchovy meal, growth performance of the shrimp significantly decreased. The four kinds of fish meal (anchovy, salmon by‐product meals and menhaden) were evaluated in an ingredient digestibility trial using the 70:30 replacement technique. In general, dry matter, energy, protein and individual amino acids digestibility of salmon meal were significantly higher than those of menhaden and anchovy meal. Results of this study demonstrated that salmon meals are a good protein sources which can replace anchovy meal.     

Evaluation of a fish meal analogue as a replacement for fish meal in practical diets for Pacific white shrimp Litopenaeus vannamei

Three six‐week growth trials and a digestibility trial were conducted to evaluate a fish meal analogue (FMA) as a replacement for fish meal (FM) in shrimp feeds. Trials 1 and 2 evaluated and confirmed the potential of FMA supplementation (0, 48.5, 97, 145.5 and 194 g/kg) as a replacement for FM up to 200 g/kg without balancing for phosphorus (P) in practical diets for juvenile Pacific white shrimp L. vannamei. At the end of trial 1, shrimp offered diets containing 48.5 g/kg FMA exhibited significantly higher weight gain (WG) than those fed with the diet containing 145.5 g/kg FMA. At the end of trial 2, dietary FMA inclusion at 48.5 and 97 g/kg significantly improved WG and protein retention (PR), while reducing FCR and protein content of shrimp body compared to the diet containing 194 g/kg FMA. To determine whether P deficiency is the cause of reduced growth, the third trial was conducted utilizing equivalent diet but balanced for P. At the end of trial 3, shrimp fed diet containing 48.5 g/kg FMA+P showed significantly higher WG and PR than those fed diet containing 145.5 g/kg FMA+P. No decreasing trend of growth was detected in the diets containing FMA compared to the FM‐based diet. Apparent digestibility coefficients of dry matter, energy, protein and amino acids of FMA were determined using chromic oxide as an inert maker and the 70:30 replacement technique. The energy, protein and individual amino acid digestibility of FMA were significantly lower than those of soybean meal and FM which were run at the same time. Results of this work indicate that FMA can replace up to 200 g/kg FM in shrimp diets with supplemental inorganic P. Given the good growth across the range of inclusion without any indication of a growth depression, the low nutrient digestibility of FMA may be due to an atypical response or the product simply does not work with the testing technique.     

Effect of replacing fish meal with soybean meal on growth,feed utilization and nitrogen and phosphorus excretion of juvenile Pseudobagrus ussuriensis

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal with soybean meal (SBM) on growth, feed utilization, and nitrogen (N) and phosphorus (P) excretion of juvenile Pseudobagrus ussuriensis (initial average weight 0.50 ± 0.00 g). Seven isonitrogenous and isolipidic diets were formulated to contain SBM to replace fish meal protein at 0% (S0), 10% (S10), 20% (S20), 30% (S30), 40% (S40), 50% (S50) and 60% (S60) respectively. To investigate the effects of supplementation with crystalline amino acid to balance diet S60, one diet was formulated to add 0.30% methionine (SM60). The results showed that there was no significant difference in weight gain among fish fed S0, S10, S20, S30 and S40 diets, however, a significant reduction in this variable occurred when 50% and 60% of fish meal protein was replaced by SBM (P < 0.05). Apparent digestibility coefficients of dry matter, crude protein and phosphorus of diets were affected by dietary SBM levels. N and P excretion indicate that fish meal replacement by SBM led to an increase in N excretion, but led to a reduction in P excretion. No differences were detected in growth, feed utilization and N and P excretion between fish feed diets S60 and SM60. The results of this study show that 40% of fish meal protein could be replaced by SBM in diets of juvenile P. ussuriensis without having a significant negative effect on growth or feed efficiency, but that higher dietary SBM levels reduce fish performance.     

The replacement of fish meal with fermented soya bean meal or soya bean meal in the diet of Pacific white shrimp (Litopenaeus vannamei)

The present study evaluated the effects of replacing fish meal (FM) with soya bean meal (SM) or fermented soya bean meal (FSM) on growth, nutrient utilization, digestive enzyme activity and intestinal histology of Pacific white shrimp. The basal diet (control) contained 18% FM, and then, FM in basal diet was replaced by 1/6 (17%), 1/3 (33%) and 1/2 (50%) by the inclusion of SM and FSM, referring to SM17, SM33, SM50, FSM17, FSM33 and FSM50 respectively. The shrimp (3.0 g) were fed one of the seven diets for 8 weeks. The results showed that the control group had the highest weight gain (WG) (653.8%) and the lowest feed conversion ratio (FCR) (1.61). SM33, SM50 and FSM50 groups showed significantly lower WG, crude protein (CP) digestibility, hepatopancreatic protease, amylase activity and higher FCR than the control (p < .05). The villi height of SM33, SM50 and FSM50 groups and the intestinal wall thickness of SM groups and FSM50 group were significantly lower than those of the control (p < .05). In conclusion, fish meal (18%) in white shrimp diet could be replaced by 1/6 (17%) and 1/3 (33%) with SM and FSM respectively. Fermented soya bean meal could replace more fish meal than soya bean meal did.     

An evaluation of pink salmon (Oncorhynchus gorbuscha) testes meal in diets for pacific white shrimp (Litopenaeus vannamei): effect on palatability,digestibility and growth performance

This study compared the nutritional profiles of menhaden fishmeal and pink salmon (Oncorhynchus gorbuscha) testes meal and investigated the nutritional values of the testes meal based on its effect on palatability, digestibility and growth performance of Pacific white shrimp (Litopenaeus vannamei). The testes meal replaced 0–91% of fishmeal protein in a control diet containing 150 g kg⁻¹ fishmeal. Replacement of 69% of the fishmeal protein in the control diet significantly increased feed intake of shrimp from 0.61% to 1.10%. The apparent digestibility coefficient of dietary protein increased significantly when 91% of the fishmeal protein was replaced by the testes meal. Replacement of dietary fishmeal protein with up to 46% testes meal protein did not cause adverse effects on growth rate or nutritional composition of tail muscle. However, growth rate was significantly decreased in shrimp fed diets in which 69% or 91% of fishmeal protein was replaced by the testes meal. Results of this study indicate that the testes meal can be used as a feed additive to enhance the palatability and protein digestibility of low fishmeal diets for shrimp. It can replace up to 46% of fishmeal protein without any adverse effect on the growth performance of shrimp.     

Potential of processed animal protein versus soybean meal to replace fish meal in practical diets for European catfish (Silurus glanis): growth response and liver gene expression

A 9‐week study was conducted to evaluate the potential of processed animal protein (PAP) in comparison with soybean meal (SM) to replace fish meal (FM) in practical diets for European catfish, Silurus glanis, on growth performance, liver transaminase activities and expression of growth‐related genes. Seven isonitrogenous (440 g kg^‐1 crude protein) and isoenergetic (16.70 MJ/kg) practical diets were formulated by replacing 0 (control), 30%, 60% and 100% FM with either SM or PAP. Each diet was randomly assigned to triplicate groups of 25 fish per cages fixed in the pond. Fish fed the diet substituted 100% FM from SM or PAP had lower (p < .05) growth performance, feed efficiency and protein retention compared to control and other groups. The decreased growth performance occurred concomitant with a decline in the expression level of liver GHR/IGF‐I axis genes. The gene expression and activity of liver protein metabolism enzymes also positively correlated with growth performance. Findings of this study indicated that both SM and PAP were equally effective in replacing FM up to 60% in the practical diet of Silurus glanis. Total replacement of FM either with SM or PAP induced negative influences on growth and feed utilization.     

Assessment of the relative contribution of dietary nitrogen from fish meal and biofloc meal to the growth of Pacific white shrimp (Litopenaeus vannamei)

The relative contribution of the dietary nitrogen supplied by fish meal and a biofloc meal to the growth of Pacific white shrimp was evaluated using stable isotope analysis. Biofloculated material was obtained from an experimental tilapia culture system. Five formulated diets were supplied. Two of them consisted in isotopic controls having only fish meal or biofloc meal as protein source. Three mixed diets were formulated with varying proportions of these ingredients on a dietary nitrogen basis (75:25, 50:50 and 25:75). At the end of the trial, survival rates were similar (92–100%) but significant differences in mean final weight were observed and a negative correlation between the inclusion of biofloc meal and weight gain was evidenced. Mean final weight in shrimp fed on diet containing only fish meal was 2.8 g, while mean final weight of animals fed on diet containing 50% biofloc was 1.9 g. Isotopic mixing models indicated that all diets contributed higher proportions of dietary nitrogen from fish meal than from biofloc meal. Dietary nitrogen available in diets containing 25%, 50% and 75% of biofloc meal was incorporated in muscle tissue as 5%, 41% and 64% respectively. Diet supplying 25% of nitrogen from biofloc was the only mixed diet eliciting growth comparable to diet containing only fish meal. Lower growth and nitrogen deposition in shrimp fed on diets containing high proportions of biofloc meal were possibly associated to the use of only two protein sources and a restriction of essential amino acids.     

Insect larvae meal as an alternative source of nutrients in the diet of Atlantic salmon (Salmo salar) postsmolt

Two insect meal (IM) products were tested as ingredient in diets for Atlantic salmon weighing ~250 g. The modern control diet contained 200 g kg^?1 fish meal (FM100), which was stepwise replaced by insect meal A (IM A) as a 25% (A25), 50% (A50) or 100% (A100) FM replacement or insect meal B (IM B) as a 25% (B25) or 100% (B100) FM replacement. Selected nutrient parameters and contaminants were measured in the diets. After 15 weeks, fish length and weight were recorded and visceral and hepatic indices calculated. Fatty acid and amino acid digestibility was calculated. Morphology of the liver, kidney, mid‐ and hind intestine was evaluated. Finally, a sensory testing of the fillets was conducted. A25, A50 and A100 performed equally well as the FM100 diet. The feed intake decreased moderately with increasing IM A inclusion; however, food conversion ratio decreased, resulting in an equal net growth of the fish. Histology did not show any differences between any of the dietary groups, and sensory testing of fillets from FM100, A100 and B25 did not reveal any significant differences in odour, flavour/taste or texture between groups. IM A was suitable to replace up to 100% of dietary FM, whilst IM B did not perform equally well.     

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.     

Effect of extrusion processing on the nutritive value of canola meal for chinook salmon (Oncorhynchus tshawytscha) in seawater

This study was conducted to evaluate three canola protein products as partial replacements of steam-dried whole herring meal (HM) in a practical diet for juvenile chinook salmon in seawater. Groups of 30–40 g chinook salmon held in 9.5–12°C seawater on a natural photoperiod were fed one of seven equivalent protein (390 g kg⁻¹) and isoenergetic (20 MJ gross energy kg⁻¹) diets to satiation. Each of three test protein sources, namely, commercial canola meal (CM), low-temperature extruded CM (90°C; LT), and high-temperature extruded CM (150°C; HT) comprised about 120 and 240 g kg⁻¹ of dietary protein by replacement of 15 and 30%, respectively, of the HM protein in the control diet. Chinook salmon growth and feed intake were markedly depressed by replacing HM protein with a high level of CM, but these responses were not lowered by replacement with LT and HT. The phytic acid content in commercial canola meal was reduced by about 10 and 30% from the original level by extrusion cooking at low (90°C) and high (150°C) temperature, respectively. Therefore, the diets containing HT still had significant amounts of phytic acid. Terminal whole-body zinc contents were inversely related to the dietary levels of the different canola protein products. Thyroid function was altered by CM but this effect was offset by heat treatment. The results suggest that extrusion cooking of CM improves its nutritive value for chinook salmon in seawater. Indeed, it was found that HT could comprise 240 g kg⁻¹ of the dietary protein without adversely affecting performance.     

Replacement of fishmeal with commercial soybean meal and EnzoMeal in juvenile barramundi Lates calcarifer

This study investigates the impact of fishmeal replacement by soybean meal (SM) and improved SM known as EnzoMeal (EZ) on fish growth performance. The SM and EZ were used in five experimental diets: fishmeal (600 g/kg) as the control diet, 50% fishmeal replaced with soybean meal (SM50), 50% fishmeal replaced with EnzoMeal (EZ50), 100% fishmeal replaced with soybean meal (SM100) and 100% fishmeal replaced with EnzoMeal (EZ100). Fish in the control group gained the most weight, followed by those under the SM50 and EZ50 diets, while the least weight gain was observed in fish fed the SM100 and EZ100 diets. The specific growth rate (SGR) was higher in the control, but was not different between fish fed SM50 and EZ50, or between SM100 and EZ100. The highest feed intake occurred in the control but decreased sequentially from fish fed SM50 to fish fed EZ50, EZ100 and SM100. Protein digestibility was best in SM50, poorest in EZ100, but no difference between the control, EZ50 and SM100 diets. This study indicates that EnzoMeal, containing high crude protein (56%), is a potential source of plant meal to replace fishmeal in the barramundi diet, but low feed intake is a challenge when EnzoMeal is >300 g/kg.     

Incorporation of a mixture of meat and bone meal,poultry by‐product meal,blood meal and corn gluten meal as a replacement for fish meal in practical diets of Pacific white shrimp Litopenaeus vannamei at two dietary protein levels

A 6‐week feeding trial was carried out in glass tanks to determine the effects of partial replacement of fish meal (FM) with a combination of meat and bone meal (MBM), poultry by‐product meal (PBM), blood meal (BM) and corn gluten meal (CGM) in practical diets on the growth, nutrient digestibility and body composition of Pacific white shrimp. Six practical diets were formulated, containing two levels of crude protein (CP) (330 and 380 g kg^?1) and similar crude lipid (CL) levels. For the 330 g kg^?1 dietary protein level, 0, 357 and 714 g kg^?1 FM were replaced by the mixture in Diets 1–3, respectively; while 0, 514 and 784 g kg^?1 FM were replaced in Diets 4–6, respectively, for 380 g kg^?1 dietary protein level. White shrimp‐fed diets containing 330 g kg^?1 CP had significantly lower weight gain compared with white shrimp fed diets containing 380 g kg^?1 CP. Increasing the mixture and dietary protein level significantly raised the body ash content of white shrimp. White shrimp fed a low‐protein diet obtained better nutrient digestibility compared with those fed a high‐protein diet.     

Substituting fish meal with poultry by-product meal in diets for black Sea turbot Psetta maeotica

A 60 days feeding experiment was carried out with Black Sea turbot Psetta maeotica to determine the amount of poultry by‐product meal (PBM) that could replace fish meal (FM) in formulated diets without reducing growth performance. Juvenile Black Sea turbot (initial average weight, 30 g) were fed five isoenergetic (gross energy, 20.5 ± 0.21 kJ g^?1 diet) and isonitrogenous diets (protein content, 550 ± 0.35 g kg^?1). The control diet used white FM as the sole protein source, the other four diets were prepared to replace FM protein at levels of 25%, 50%, 75% and 100% with PBM. The fish readily accepted all experimental diets and no mortality were recorded during the trial. There were no significant differences in growth performance of turbot (P < 0.05) fed the diets with 25% and 50% replacement levels compared with fish offered the control diet (100% FM), however, final body weight and specific growth rate values in the 50% replacement diet were about 8% lower than those of the control. Total nitrogen excretion in fish fed 50% replacement diet were about 10% higher than the control group, even though these parameters were not found to be statistically different. At the levels of 750 and 1000 g kg^?1 of the protein, PBM inclusion caused a severe decrease in growth performance, feed utilization, protein efficiency ratio and per cent nitrogen retention. The results in the present study indicate that up to 25% of FM protein can be replaced by PBM protein without causing reduction in growth performance, nutrient utilization and nitrogen retention.     

Evaluation of potential of lupin meal as an alternative to fish meal in juvenile Penaeus monodon diets

An indoor feeding trial in a flow-through marine water system was performed to evaluate the feasibility of using dehulled lupin Lupinus albus seed meal as a protein source to replace fish meal in diets for the juvenile Penaeus monodon. Five isonitrogenous (40% crude protein) diets formulated by replacing 0, 25, 50, 75, and 100% of fish meal protein by lupin meal protein were fed to shrimp (mean initial weight of 4.32 ± 0.23 g) three times daily at a feeding allowance of 5% body weight per day for 42 days. Shrimp fed diets with 0, 25, 50 and 75% replacement had similar (P > 0.05) weight gain, dry matter feed intake, feed conversion ratio (FCR), protein efficiency ratio (PER), and apparent net protein utilization (ANPU). Shrimp fed the highest dietary inclusion level of lupin meal (100% replacement) had significantly (P < 0.05) lower responses for all the above parameters than shrimp fed all other diets. Survival was high (87–100%) and similar for all diets. Apparent dry matter digestibility (ADMD) of diets with 25, 50, 75 and 100% replacement of fish meal with lupin meal was similar (75.6–76.6%) and significantly (P < 0.05) higher than that of diet with 0% replacement (73.9%). Diets containing the two highest lupin inclusion levels (75 and 100% replacement) had significantly (P < 0.05) better apparent protein digestibility (APD) than those containing the two lowest lupin meal inclusion levels (0 and 25% replacement). There were no significant differences (P > 0.05) in whole-body composition (dry matter, protein, lipid and ash) of shrimp fed on the various diets. Pellet water stability was inversely related to level of lupin meal inclusion. It was found, in this study, that up to 75% protein of fish meal can be replaced with the protein of dehulled lupin seed meal in diets for juvenile P. monodon. The diet with total replacement of fish meal containing 40% lupin meal was utilized very poorly by the shrimp.     

Replacement of fish meal by meat and bone meal in practical diets for the white shrimp Litopenaeus vannamai (Boone)

The use of meat and bone meal (MBM) was evaluated as a replacement for fish meal in a practical diet formulated to contain 41% protein and 8% lipid. Anchovy meal was replaced by 0%, 20%, 30%, 40%, 50%, 60% and 80% of MBM (diets 1–7) respectively. Healthy post larvae of Litopenaeus vannamei were reared in an indoor, semi‐closed recirculating system. Each dietary treatment was fed to triplicate groups of 40 shrimp per tank (260 L) arranged in a completely randomized design. The shrimp were hand‐fed to near‐satiation three times daily between 07:00 and 18:00 hours for 56 days. There were no significant differences (P>0.05) in growth performance among shrimp fed diets 1–6. However, shrimp fed diet 7 had significantly lower (P<0.05) growth than those fed diet 2 or diet 4. Survival ranged from 95% to 100% and did not significantly (P>0.05) differ. Feed conversion ratio (FCR) and carcass composition of the shrimp were not significantly (P>0.05) affected by dietary treatments. No significant differences (P>0.05) in protein efficiency ratio (PER) were found among shrimp fed diets 1‐6. However, shrimp fed diet 7 had significantly lower (P<0.05) PER than those fed diet 1 or diet 4. Results showed that up to 60% of fish meal protein can be replaced by MBM with no adverse effects on growth, survival, FCR, PER and body composition of L. vannamei.     

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.     

Evaluation of a novel bacterial biomass as a substitution for soybean meal in plant‐based practical diets for Pacific white shrimp Litopenaeus vannamei

Three growth trials and a digestibility trial were designed to evaluate the efficacy of a novel bacterial biomass (BB) in commercial‐type feed formulation for Pacific white shrimp, Litopenaeus vannamei. In trial 1, the basal diet was supplemented with 0, 60 and 120 g/kg BB to replace soybean meal (SBM). Significant improvement was observed in the survival when BB was incorporated in the diets. However, shrimp fed diets containing 120 g/kg BB exhibited significantly lower weight gain (WG) and higher feed conversion ratio (FCR). To confirm the results from trial 1 and explore the effects of BB supplementation at low levels, the basal diet was incorporated with 0, 10, 20, 40, 60 and 120 g/kg BB to replace SBM in trial 2. Significant reductions in WG, FCR, lipid content of whole body, protein retention efficiency and most amino acids retention efficiency were detected in shrimp fed with diet containing 120 g/kg BB. Trial 3 was designed to elucidate whether the digestible protein is the cause of reduced growth. No improvements in terms of growth performance and FCR were detected in the treatments balanced for digestible protein. Apparent digestibility coefficients of energy, protein and amino acid (AA) for BB were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy, protein and individual amino acid digestibility coefficients of BB were significantly lower than those of fish meal (FM) and SBM that were given at the same time. Results of this study indicated that BB can be utilized up to 40 g/kg in shrimp feed without causing a decrease in growth. However, supplementations (≥60 g/kg) of BB can result in negative effects on growth response, FCR and protein as well as amino acids retention efficiency. At the lower levels of inclusion, shrimp performance was improved when BB was supplemented on a digestibility basis; however, at the higher level of inclusion, there was no improvement, indicating there may be other nutrients limiting. Based on enhanced survival in the treatment with BB supplementation in trial 1, further research regarding the immune effects of BB in practical shrimp feed will be necessary.     

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.     

Evaluation of dried fermented biomass as a feed ingredient in plant‐based practical diets for juvenile Pacific white shrimp Litopenaeus vannamei

Two growth trials were designed to evaluate the utilization of dried fermented biomass (DFB) in commercial type feed formulation for Pacific white shrimp, Litopenaeus vannamei. In trial 1, four experimental diets were formulated to utilize increasing levels (0, 25, 50 and 100 g/kg) of spray‐dried fermented biomass (SDFB) as a replacement of fish meal (FM). Results indicated that SDFB can be utilized up to 50 g/kg as a substitution for FM without causing growth depression in shrimp. However, dietary SDFB supplementation at 100 g/kg significantly reduced the weight gain (WG) of shrimp and increased feed conversion ratio (FCR). This reduction in performance is likely due to palatability or nutrient imbalances of the feed. In trial 2, nine experimental diets were formulated with increasing levels (0, 20, 40, 60 and 120 g/kg) of spray‐dried (S) or granular (G) DFB to replace soy protein concentrate (SPC) or SPC + corn protein concentrate (CPC). This allowed the comparison between spray‐dried and ring‐dried products. Ring drying produced a granular product, reducing dust and increasing product particle size. Shrimp fed with diet containing 20 g/kg GDFB performed the best in terms of final mean weight, WG and FCR. Significantly reduced growth and increased FCR were observed in shrimp fed diets containing 60 and 120 g/kg SDFB. Lipid content of whole body was significantly reduced when GDFB was incorporated at 120 g/kg. No significant differences were detected in survival, protein retention efficiency as well as protein and ash contents of the whole shrimp. Results from analysis of covariance indicated that the processing method (covariant) had a significant effect on final mean weight, WG and FCR. In general, shrimp fed with diet containing granular product performed better as compared to those fed with diets utilizing spray‐dried product. GDFB can be utilized in the diets up to 120 g/kg in practical shrimp feeds as a substitute for SPC and CPC without compromising the growth of shrimp. However, a significant reduction in WG was observed in the diets containing 60 and 120 g/kg SDFB. The results in the current study demonstrate that processing changes to produce a granular product produced an improved feed ingredient for shrimp.     

Evaluation of skate meal and sablefish viscera meal as fish meal replacement in diets for Pacific threadfin (Polydactylus sexfilis)

The objectives of this study were to investigate the nutritional value of skate meal and sablefish viscera meal from Alaskan fishery processing and to ascertain their suitability as replacements for pollock fishmeal in diets for Pacific threadfin (Polydactylus sexfilis). Test diets were made by replacing 50% or 100% protein from fish meal in the control diet with skate or sablefish viscera meal. The test diets and a commercial feed were each assigned to four tanks with eight juvenile fish (9.7 g) per tank in an indoor flow‐through culture system. After 6 weeks, Pacific threadfin fed skate meal‐50% and ‐100% substituted diets exhibited similar weight gains (374%; 369%) and feed conversion ratios (1.29; 1.27) as those fed the control diet (345%; 1.30 respectively) (P > 0.05). In contrast, Pacific threadfin fed the sablefish viscera meal‐50% substituted diet exhibited significantly lower weight gain (112%) than fish fed the control diets (P < 0.05). The fish fed the control diet and skate meal substituted diets also achieved significantly higher (P < 0.05) weight gain than those fed the commercial feed (288%). In conclusion, skate meal can fully replace the commercial fishmeal in a Pacific threadfin diet without adversely effecting growth performance.