Response of juvenile tench (Tinca tinca L.) fed practical diets with different protein contents and substitution levels of fish meal by soybean meal

A basal practical diet for juvenile tench (Tinca tinca) was formulated and elaborated to test several protein contents and substitution possibilities of fish meal (FM) by soybean meal (SBM) in a 90‐day trial with 5‐month‐old juveniles (30.54 mm TL, 0.30 g W). A factorial design included nine feeding treatments: three protein contents (50%, 40% or 30%) and three levels of replacement (0%, 25% or 45%) of FM protein by SBM protein. In addition, a commercial carp feed was used as reference. Final survival ranged from 98.2% to 99.4%. The 50% dietary protein with 0% or 25% replacement and 40% dietary protein with 25% replacement diets enabled higher growth (P < 0.05) and lower FCR (P < 0.05) than the rest of practical diets. Fish fed 50% dietary protein had similar growth than those fed carp feed (63.8% protein). Deformed fish averaged 1% for the practical diets and 87.6% for the carp feed. The basal practical diet has showed to be feasible and levels of 40–50% dietary protein with 25% replacement of FM protein by SBM protein can be recommended for juvenile tench aged 5–8 months.     

Effects of fish meal replacement with animal protein blend on growth performance,nutrient digestibility and body composition of juvenile Chinese soft‐shelled turtle Pelodiscus sinensis

An 8‐week feeding trial was conducted to evaluate the potential of partial replacement of fish meal with rendered animal protein blend (APB) [meat and bone meal (MBM): expanding blood meal (EBM) = 4 : 1] in the diet of juvenile Chinese soft‐shelled turtle Pelodiscus sinensis. Seven isonitrogenous and isoenergetic practical diets replacing 0%, 10%, 20%, 30%, 40%, 50% and 60% fish meal protein by APB were formulated. Weight gain, feed efficiency, protein efficiency and the apparent digestibility coefficients (ADCs) of dry matter and gross energy in the experimental diets all exhibited no significant difference (P > 0.05) when dietary fish meal was replaced for 0–40%, but decreased significantly (P < 0.05) with further increasing substitution levels. However, relative feed intake, ADC of lipid as well as the contents of whole‐body moisture, protein, lipid and ash all showed little differences (P > 0.05) among all the treatments. Nitrogen retention and the ADCs of protein and most amino acids all decreased significantly (P < 0.05) when fish meal was substituted by more than 30%. The results indicated that fish meal in the practical diet of juvenile Chinese soft‐shelled turtle could be replaced by 30–40% using a combination of MBM and EBM without negative effects on growth performance, nutrients digestibility and body composition.     

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.     

Replacement of fish meal with poultry by-product meal in diets formulated for the humpback grouper, Cromileptes altivelis

An eight-week feeding trial was conducted to examine the possibility of replacing fish meal with poultry by-product meal (PBM) at high inclusion levels in the diets of the humpback grouper, Cromileptes altivelis, a carnivorous marine tropical fish. Six isolipidic (12%) and isoproteic (50%), experimental diets were formulated to contain graded levels of PBM. Fish meal protein was replaced with a feed-grade PBM at 50, 75 or 100% level (FPBM50, FPBM75, FPBM100, respectively), or a pet food grade PBM at 75 or 100% replacement level (PPBM75 and PPBM100, respectively). The control diet contained Danish fish meal as the sole protein source. The experimental diets were fed close to apparent satiation, twice a day to triplicate groups of humpback grouper fingerlings (12.4 ± 0.2 g). The grouper fingerlings were randomly distributed into groups of 15 fish in cylindrical cages (61 cm depth and 43 cm diameter) and placed in a 150-ton seawater polyethylene tank. Except for fish fed the FPBM100 diet, growth performance, survival, and feed utilization efficiency for fish fed PBM-based diets were not significantly lower (P > 0.05) compared to fish fed the control diet. The PBM source and dietary level did not significantly affect (P > 0.05) the hepato- and visero-somatic indices or the condition factor of fish. Dry matter and protein apparent digestibility coefficients (ADC) of the diets decreased with increasing dietary PBM, and ranged from 64.3-71.5% and 86.2 to 91.2%, respectively. High values (91.7 to 96.7%) for lipid ADC were observed in all diets, with no significant differences among dietary treatments. Whole-body moisture and lipid contents of the fish were not affected by the inclusion of PBM in the diets. With the exception of fish fed the FPBM100 diet, whole-body protein of fish fed the PBM-based diets was slightly higher than that of fish fed the control diet. There was a trend of increased whole-body ash with the increase in dietary levels of PBM. The results from this study indicate that good quality terrestrial PBM can successfully replace more than half the protein from marine fish meal in the diets for humpback grouper. However, total replacement of fish meal with PBM might be constrained by lowered nutrient digestibility and limiting essential amino acids, especially lysine and methionine.     

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.     

Replacing fish meal with a blend of poultry by‐product meal and feather meal in diets for giant croaker (Nibea japonica)

An 8‐week feeding trial was conducted to evaluate the potential of replacing fish meal with poultry by‐product meal (PBM) and feather meal (FEM) in giant croaker (Nibea japonica) diet. The control diet (C) contained 400 g/kg fish meal, and 20%, 40%, 60% and 80% of the fish meal in diet C was replaced by a blend of PBM and FEM (PBM: FEM = 7:3) in diets B20, B40, B60 and B80, respectively. The weight gain and feed intake of fish fed diet C did not differ from those of fish fed diets B20 and B40 (p > .05), but were higher than those of fish fed diets B60 and B80 (p < .05). Phosphorus retention efficiency was lower in fish fed diets C, B20 and B40 than in fish fed diets R60 and R80 (p < .05). No significant differences were found in feed conversion ratio, nitrogen retention efficiency, condition factor, hepatosomatic index, body composition and nitrogen waste among the treatments (p > .05). Ratio of fish meal consumption to fish production linearly declined with the decrease in dietary fish meal level. This study indicates that dietary fish meal for giant croaker could be reduced to 240 g/kg by inclusion of the blend of PBM and FEM.     

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.     

Effects of replacing fish meal with corn gluten meal on growth,feed utilization,nitrogen and phosphorus excretion and IGF‐I gene expression of juvenile Pseudobagrus ussuriensis

Seven isonitrogenous and isolipidic diets containing fish meal (FM) protein replaced by corn gluten meal (CGM) protein at 0% (the control, C0), 10% (C10), 20% (C20), 30% (C30), 40% (C40), 50% (C50) and 60% (C60) were fed to juvenile Pseudobagrus ussuriensis for 8‐weeks to evaluate the effects of FM protein replaced by CGM protein on growth, feed utilization, nitrogen (N) and phosphorus (P) excretion and IGF‐I gene expression of juvenile P. ussuriensis. The results showed that the replacement level up to 40% did not affect the weight gain, specific growth rate (SGR), feed intake and protein efficiency ratio, whereas these parameters were depressed by further replacement level. Apparent digestibility coefficients (ADC) of dry matter, crude protein significantly decreased, but ADC of phosphorus significantly increased with increasing dietary CGM levels (p < .05). Fish fed diets with FM protein replaced by CGM protein led to an increase in nitrogen excretion, but led to a reduction in phosphorus excretion. No significant differences were observed in alpha‐amylase and lipase activities of intestine (p > .05). The lowest pepsin activity was found in C60 group. Fish fed diet C40, C50 and C60 had significantly lower serum lysozyme activity compared with fish fed diet C0 (p < .05). The lowest plasma alkaline phosphatase activity and the highest plasma alanine aminotransferase and aspartate aminotransferase activities were observed in C60 group. Fish fed diet C60 had significantly lower hepatic IGF‐I gene expression compared with fish fed diet C10 (p < .05). Broken‐line model analysis based on SGR against the CGM substitution level indicated that the appropriate replacement level was 37.7%.     

Effects of canola meal on physiological and biochemical parameters in rainbow trout (Oncorhynchus mykiss)

Rainbow trout (initial body weight 4.16 ± 0.25 g) were fed diets [crude protein 420 g kg^?1; gross energy 18.7 MJ kg^?1 dry matter (DM); crude fat 110 g kg^?1] containing graded levels of either a canola meal (crude protein 350 g kg^?1 DM) supplemented with DL‐methionine as partial fish meal protein. A growth trial was conducted over 16 weeks at a water temperature of 12 ± 1 °C. At the end of the growth trial, in addition to body composition analyses, plasma tri‐iodothyronine (T₃) and thyroxine (T₄), cholesterol and liver fatty acid composition were measured. Replacement of fish meal with canola meal (100–570 g kg^?1 replacement) did not affect on growth performance. At 16th week, plasma cholesterol levels were reduced in fish fed all diets in comparison with 8th week. Plasma T₄ levels were significantly higher in the canola meal‐fed fish sampled after 16 weeks, but no significant differences in T₃ levels were obtained (P > 0.05). Proximate compositions were affected by dietary treatments. The liver fatty acid composition reflected that of the diet with a higher level of polyunsaturated (n‐6) fatty acids in fish fed diet canola meal and a higher content in n‐3/n‐6 ratio in fish fed diet without canola meal. These studies show that canola meal has potential to replace substantial levels of fish meal in diets for carnivorous fish without compromising performance.     

Effects of dietary inclusion of soybean meal and cholesterol on the growth,cholesterol status and metabolism of the giant grouper (Epinephelus lanceolatus)

The study evaluated effects of cholesterol supplementation in a diet with high soybean meal (SBM) on the growth and cholesterol metabolism of giant grouper (Epinephelus lanceolatus). All‐fish‐meal diet was used as control. The diet including SBM (replaced 50% of the fish meal protein, SBM diet) and the SBM diet supplemented with 10 g/kg cholesterol (SBM + cholesterol) were used as experimental diets. Three diets were each fed to triplicate groups of juvenile grouper (initial body weight: 12.39 ± 0.36 g) in a recirculating aquaculture system for 8 weeks. Grouper fed the control diet showed higher (p < .05) weight gain, feed intake, feed efficiency and protein efficiency ratio than the other two dietary treatments. Hepatic cholesterol concentrations and 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase gene expressions were higher in fish fed the control diet than fish fed the control diet and SBM + cholesterol diet. Hepatic cholesterol 7α‐hydroxylase gene expression was higher in fish fed the SBM + cholesterol diet than that in fish fed the control diet. Results indicate that giant grouper on a diet low in cholesterol can regulate cholesterol synthesis, suggesting that the reduced dietary cholesterol intake in the fish fed diet containing SBM is sufficiently compensated by increased cholesterol synthesis.     

The potential of pet‐grade poultry by‐product meal to replace fish meal in the diet of the juvenile spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

A 12‐week feeding trial was conducted to examine the replacement of fish meal with pet‐grade poultry by‐product meal (PBM‐PG) in the spotted rose snapper Lutjanus guttatus diet. Five experimental diets were formulated to contain graded levels of PBM‐PG at proportion of 250, 500, 75 or 900 g kg^?1. The control diet contained sardine fish meal as the main protein source. Four groups of 15 randomly assigned L. guttatus juveniles were fed to satiation 3 times day^?1. Except for the fish fed the PBM‐PG90 diet, the growth performance, survival and feed utilization efficiency of the experimental fish were not significantly lower than those of the control fish. The dietary level of PBM‐PG did significantly affect the haematological characteristics (P < 0.05). The dietary dry matter and protein apparent digestibility coefficients (ADCs) decreased with increasing dietary PBM‐PG. High values for lipid ADCs were observed in all diets, with significant differences among the dietary treatments. The fish whole‐body protein, moisture, lipid and ash contents were not affected by the inclusion of dietary PBM. These results indicate that high‐quality terrestrial PBM can successfully replace more than half of the marine fish meal protein in the L. guttatus diet.     

Effect of replacement of dietary fish meal with silkworm pupae meal on growth performance,body composition,intestinal protease activity and health status in juvenile Jian carp (Cyprinus carpio var. Jian)

This study investigated the effect of replacement of graded dietary fish meal (FM) protein (0, 50%, 60%, 70% and 80%) with silkworm pupae meal (SP) in juvenile Jian carp. Triplicate groups comprising 18 fish (15.96 ± 0.66 g) were fed one of five isonitrogenous and isocaloric diets (designated SP0, SP50, SP60, SP70 or SP80) for 8 weeks. The final body weight and specific growth rate of fish in the SP60, SP70 and SP80 groups were significantly lower than those for fish in the SP0 group (P < 0.05). The muscle protein content in the SP50 group was significantly higher than in the SP80 group (P < 0.05). With increasing FM replacement levels, the hepatic superoxide dismutase (SOD) activity decreased and the malondialdehyde (MDA) content increased among the groups, with the significant difference appeared in SP80 group. The gene expression level of heat shock protein 70 in the SP70 group was significantly higher than in the SP0 group (P < 0.05), while that in the SP80 group was significantly less than in the SP70 group (P < 0.05). Significantly decreased intestinal protease activity, increased serum ALT and AST activities, irregular‐shaped hepatocytes and intestinal microvilli were found in the SP80 group. The study demonstrates that it is practical to replace 50% of the Jian carp dietary FM protein with SP, higher SP levels are not recommended and that oxidation status of the SP should be carefully assessed.     

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.     

Effect of partial replacement of dietary fish meal by soybean meal with betaine attractant supplementation on growth performance and fatty acid profiles of juvenile rainbow trout (Oncorhynchus mykiss)

This study was conducted to investigate the effects of dietary incorporation of soybean meal for fish meal replacement and supplementation of betaine as an attractant on growth performance and fatty acid profiles of rainbow trout (Oncorhynchus mykiss). Juvenile trout were fed practical diets, with increasing soybean levels and betaine supplementations. The experimental diets consisted of a control diet with fish meal as the sole protein source (control) and no attractant, 25% soybean‐1% betaine diet (SBM25‐B1), 50% soybean‐2% betaine diet (SBM50‐B2), and 50% soybean‐0% betaine diet (SBM50‐B0). Average body weight was 12.69 ± 0.16 g at the beginning of experiments. Following 54 days feeding programme with experimental diets, average body weights reached 47.45 ± 1.22 g, 58.11 ± 1.77 g, 56.34 ± 1.87 g and 53.76 ± 1.74 g in the control, SBM25‐B1, SBM50‐B2 and SBM50‐B0 groups respectively. As compared with control treatment, significant differences were observed in weight gain, specific growth rate and feed intake of 1% betaine treatment at 25% soybean‐meal‐incorporated diet (p < .05), but no differences were observed in feed conversation ratio and survival rates (p > .05). Compared with the control treatment, betaine‐supplemented groups had significantly higher total saturated fatty acid contents (p < .05). On the other hand, the control treatment showed a significantly higher level of monounsaturated fatty acid than the betaine‐supplemented groups (p < .05). Significant differences were observed in fatty acid profile of 1% betaine‐supplemented group (p < .05) compared with the control. Present findings revealed that 1% betaine supplementation with dietary incorporation of soybean meal at 25% level positively influenced growth performance, feed utilization and fatty acid profiles of rainbow trout juveniles.     

Effect of partial replacement of fish meal with soybean meal and feeding frequency on growth,feed utilization and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus (Bleeker)

A factorial (2 × 4) feeding trial was conducted to investigate the effects of feeding frequency and partial replacement of fish meal (FM) with soybean meal (SBM) on the growth performance, feed utilization and body proximate composition of juvenile Chinese sucker. Two feed types including replacement of 30% FM (diet 1) with SBM (diet 2) were used. Triplicate groups of fish (average weight, 11.80 ± 0.19 g) were fed each feed type to visual satiation at four meals per day, three meals per day, two meals per day and one meal per day for 8 weeks. At the end of the feeding trial, the survival of fish was not significantly different among the treatments. Weight gain was affected by the feeding frequency. The highest weight gain was observed in fish fed with diet 1 at three meals per day. There existed a significant difference in daily feed intake (DFI), daily protein intake (DPI), feed conversion ratio (FCR) and protein efficiency ratio (PER) when the feeding frequency was increased from one or two to three or four meals per day (P < 0.001), but not by the feed types. For both two feed types, the highest DFI and DPI were observed at three meals per day. The highest PER was gained at four meals per day, while FCR was the least. The body proximate composition of fish was altered by feeding frequency. The crude lipid content increased with the increase in feeding frequency. Essential amino acids (EAAs) content showed no significant differences among different treatments. The present findings suggest that three feedings per day at visual satiation may be sufficient for the maximal growth performance of Chinese sucker grown from 11 to 45 g. Results also indicate that about 30% of FM protein can be replaced by SBM protein in Chinese sucker diets without adversely affecting growth.     

Evaluation of fermented soybean meal in the practical diets for juvenile Chinese sucker,Myxocyprinus asiaticus

The study was designed to investigate the influence of fermented soybean meal (FSBM) on the growth and feed utilization of juvenile Chinese sucker, Myxocyprinus asiaticus. Seven isonitrogenous and isolipidic diets were formulated with 0%, 15%, 25%, 35%, 45%, 55% or 65% replacement of fish meal with FSBM on a protein basis. Each diet was fed to three replicate groups of fish with an initial weight 4.59 ± 0.2 g for 8 weeks. Weight gain (WG) and specific growth rate (SGR) was significantly lower when FSBM inclusion was 391 g kg^?1 or greater, replacing more than 45% fish meal protein. A significant negative relationship was observed between growth response and the level of fish meal protein replacement with FSBM. Methionine and Lysine content decreased as FSBM inclusion levels increased, consequently compromising growth performance. Feed intake (FI) were unaffected by dietary FSBM levels. The feed conversion ratio (FCR) of fish fed D‐0, D‐15, D‐25 and D‐35 diets was significantly lower than those fed other diets. The protein efficiency ratio (PER) was highest at the lowest FSBM inclusion level. Experimental diets D‐0, D‐15, D‐25 and D‐35 had apparent dry matter digestibility ranging from 71.2% to 72.6% and apparent protein digestibility (ADPs) from 89.1% to 90.1%, while the diets with higher FSBM inclusion (D‐45 to D‐65) had a significantly lower apparent dry matter digestibility range (69.7–70.3%) and ADPs range (88.5–88.9%). It is concluded that FSBM is an acceptable alternative plant protein source that can replace up to 35% of fish meal protein in diets without significant adverse effects on growth, survival, FCR, PER and body composition.     

Supplementations of poultry by‐product meal and selenium yeast increase fish meal replacement by soybean meal in golden pompano (Trachinotus ovatus) diet

The effects of poultry by‐product meal (PBM) and selenium yeast (Se‐yeast) supplementations on fish meal replacement by soybean meal (SBM) in the diet of golden pompano (Trachinotus ovatus) were examined. In trial I, a 2 × 3 layout including two PBM levels (100 and 170 g kg^?1) and three levels of fish meal replacement (0, 40 or 60%) was used. At 100 g kg^?1 PBM, fish fed the basal diet exhibited the highest weight gain (WG) and nitrogen retention efficiency (NRE) and the lowest feed conversion ratio (FCR). At 170 g kg^?1 PBM, no significant differences were found in WG and NRE between fish fed the basal diet and diet with 40% of fish meal replaced by SBM. In trial II, the basal diet containing 170 g kg^?1 PBM (trial I) served as a reference. A 2 × 2 layout included two levels of fish meal replacement (40 or 60%) and two levels of Se‐yeast addition (0 and 1 g kg^?1). No significant differences were found in WG, feed intake, FCR and NRE between fish fed the reference diet and diet with 40 or 60% fish meal replacement plus 1 g kg^?1 Se‐yeast addition. This study indicates that supplementations of PBM and Se‐yeast can enhance the level of fish meal replacement by SBM in golden pompano diet. Dietary fish meal level can be reduced to 140 g kg^?1 by optimizing inclusion of SBM, PBM and Se‐yeast.     

Evaluation of Schizochytrium meal in microdiets of Pacific white shrimp (Litopenaeus vannamei) larvae

A feeding trial was conducted to assess the effects of dietary Schizochytrium meal supplementation on survival, growth performance, activities of digestive enzymes and fatty acid composition in Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Four isonitrogenous and isolipidic diets were formulated to contain graded levels of Schizochytrium meal: 0% (S0, the control diet), 2% (S2), 4% (S4) and 6% dry matter (S6). Results showed that there was no significant difference in survival of shrimps among dietary treatments (P > 0.05). Shrimps fed diets with 2% and 4% microalgae meal had significantly higher specific growth rate (SGR) than that of shrimps fed diets with 0% and 6% microalgae meal, and no significant differences were observed between shrimps fed diets with 2% and 4% microalgae meal (P > 0.05). Activity of trypsin in the pancreatic and intestinal segments, and activity of amylase in the pancreatic segments were not significantly affected by dietary microalgae meal levels (P > 0.05). Specific activities of both alkaline phosphatase and leucine‐aminopeptidase in intestine and purified brush border membrane of intestine were significantly higher in shrimps fed diet with 2% microalgae meal (P < 0.05). There were no significant differences in C18:2n‐6, n‐3 fatty acids, n‐6fatty acids, PUFA and n‐3/n‐6 in muscle samples among dietary treatments. C16:1n‐7, C18:1n‐9, MUFA, C18:3n‐3 and C20:5n‐3 decreased, however, C20:4n‐6 increased in the muscle as dietary microalgae meal level increased. In conclusion, 4% Schizochytrium meal in microdiets of shrimps can improve growth performance and may be a valuable additive in the microdiets of shrimps.     

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.     

Nutritive values of low and high fibre canola meals for shrimp (Penaeus vannamei)

This study was undertaken to determine acceptable dietary concentrations of high-fibre canola meal (CMHF) and low-fibre canola meal (CMLF) for juvenile shrimp, Penaeus vannamei. Four groups of 0.78 g shrimp held in running, 24.0–27.8°C sea water on a 12 h light: 12 h dark cycle were each fed one of seven isonitrogenous (340 g kg^?1 protein) and isoenergetic (18.5 MJ of gross energy kg^?1) diets to satiation four times daily for 56 days. Each of the test canola protein products comprised either 150, 300 or 450 g kg^?1 of the protein in a basal (practical) diet by replacement of one-third, two-thirds or all of the menhaden meal protein. Shrimp that ingested diets in which CMHF and CMLF comprised 450 and 300 g kg^?1 of the protein, respectively, exhibited significant reductions in growth and feed intake relative to those fed the basal diet. Feed and protein utilization were not significantly depressed unless menhaden meal in the basal diet was completely replaced by CMHF or CMLF. In general, percentage survival and final whole-body levels of protein, minerals, and thyroid hormones were not significantly affected by dietary treatment. Terminal whole-body levels of moisture were raised significantly in shrimp fed diets containing the highest levels of CMHF and CMLF. Potassium levels were significantly higher in shrimp fed the diet containing the lowest level of CMLF relative to those fed the basal diet and the diet with the highest level of CMLF. Water stability of the diet pellets was negatively correlated with their levels of CMHF and CMLF. It is concluded that commercial high-fibre canola meal can constitute 300 g kg^?1 of the dietary protein of juvenile shrimp (Penaeus vannamei) without compromising growth, feed intake and feed and protein utilization. However, because of a trend towards reduced shrimp survival at this dietary concentration of canola meal, it is recommended that this protein source not exceed 150 g kg^?1 of the protein in practical juvenile shrimp diets. Fibre-reduced canola meal did not have improved nutritive value for shrimp. However, we postulate that one or more fibre-reduced, and solvent-extracted canola protein products may be cost-effective substitutes for fish meal protein.