Chlorella additive increased growth performance,improved appetite and immune response of juvenile crucian carp Carassius auratus

This study was designed to investigate effects of dietary Chlorella meal (CM) additive on growth performance, immune responses and appetite regulation of juvenile crucian carp Carassius auratus (initial body weight: 1.27 ± 0.03 g). Four experimental diets were formulated to contain 0% (CM0), 1% (CM1), 2% (CM2) and 4% Chlorella meal (CM4), respectively. Each diet was randomly assigned to triplicate groups with 40 juvenile fish per fibreglass tank for 8 weeks. Weight gain rate, specific growth rate and feed intake increased with increasing dietary CM levels. In contrast, FCR (feed conversion rate) declined with dietary CM levels. No significant differences were observed in moisture, crude protein, crude lipid and ash contents of muscle and liver tissues. Dietary CM addition increased activities of acid and alkaline phosphatase in liver and kidney. Dietary CM up‐regulated the mRNA expression levels of NKEF‐B, MCHII and IgM in kidney, and increased the mRNA levels of NPY and agouti gene‐related protein in the brain, but down‐regulated mRNA levels of MC4R, LEP, LEPR, CART1, CART2 and CCK8 genes. Based on these observations above, this study indicated that dietary CM additive increased growth performance, immune responses and appetite of crucian carp. The results, for the first time, demonstrate a role for the central nervous system in the control of food intake in fish fed dietary Chlorella meal.     

饲料中添加晶体或包膜氨基酸对异育银鲫生长和血清游离氨基酸水平的影响

进行了二个试验考察饲料中添加晶体或包膜氨基酸对异育银鲫生长和血清游离氨基酸水平的影响。试验Ⅰ设计了鱼粉含量为18%和9%的两种基础饲料(分别为高鱼粉对照组、低鱼粉对照组),在低鱼粉对照组中分别添加晶体形式、环糊精包膜、淀粉包膜的赖氨酸0.23%、蛋氯酸0.09%,饲养平均体重2.48 g的异育银鲫鱼种6周。结果表明,高鱼粉对照组、低鱼粉对照组、晶体氨基酸组、环糊精包膜氨基酸组、淀粉包膜氨基酸组的鱼体增重率分别为214.3%、169.8%、173.3%、204.7%、203.2%,与低鱼粉对照组相比,添加晶体氨基酸对异育银鲫的生长无改善(P>0.10),但添加环糊精包膜或淀粉包膜氨基酸提高了鱼体增重率20.5%、19.7%(P<0.05),饲料系数下降0.40、0.39(P<0.05)。试验Ⅱ在鱼粉含量为6%的基础饲料分别添加晶体形式、环糊精包膜、淀粉包膜的赖氨酸0.20%、蛋氨酸0.08%,在异育银鲫成鱼(平均体重220 g)摄食上述4种饲料后1、3、5、12h,尾静脉采血测定血清游离氨基酸浓度,结果表明,添加晶体氨基酸使血清游离氨基酸的吸收峰值提前,相对于晶体氨基酸而言,环糊精包膜或淀粉包膜氨基酸则使血清游离氨基酸的吸收峰值出现不同程度的延迟。上述研究表明,晶体氨基酸经环糊精、淀粉包膜处理后,其在消化道的吸收速度减缓,可利用性显著提高。     

α-酮戊二酸对松浦镜鲤肠道形态与功能的影响

本试验旨在研究不同蛋白源饲料中添加α-酮戊二酸(AKG)对松浦镜鲤肠道形态与功能的影响。在水温23℃下,将初始体质量为(217.93±0.78)g的松浦镜鲤Cyprinus carpio Songpu 400尾,随机分成4组,每组5个重复,每个重复20尾鱼,饲养在控温循环水系统中,投喂4种在不同蛋白源的等氮等脂饲料中添加不同剂量的α-酮戊二酸(AKG)的饲料10周,即饲料1(44%豆粕+0%AKG)、饲料2(44%豆粕+1.5%AKG)、饲料3(30%豆粕+10%鱼粉+0%AKG)、饲料4(30%豆粕+10%鱼粉+1.5%AKG),饲料中蛋白质和脂肪水平分别为28%和5.1%。结果表明:不同蛋白源饲料中添加AKG能显著提高松浦镜鲤后肠皱襞高度、前肠肌层厚度和前肠Na+,K+-ATP酶活性(P0.05);蛋白源和AKG对肠道形态指标和Na+,K+-ATP酶活性无显著交互作用(P0.05);饲料中蛋白源添加AKG能显著提高松浦镜鲤前肠和中肠蛋白酶、脂肪酶活性(P0.05),蛋白源和AKG对后肠蛋白酶活性具有显著交互作用(P0.05)。综上所述,饲料中添加1.5%AKG可以促进松浦镜鲤肠道发育,增强肠道消化酶活性。     

Replacement of Fishmeal by a Mixture of Soybean Meal and Chlorella Meal in Practical Diets for Juvenile Crucian Carp,Carassius auratus

A growth trial was conducted to evaluate the effect of a mixture of soybean meal and Chlorella meal (SCM) as a dietary fishmeal (FM) substitute on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities, and histology of juvenile crucian carp, Carassius auratus. Five isonitrogenous and isoenergetic diets were formulated to replace 0 (SCM0), 25 (SCM25), 50 (SCM50), 75 (SCM75), and 100% (SCM100) of protein from FM with SCM, respectively. The diets were fed to triplicate groups of juvenile crucian carp for 6 wk. Weight gain, specific growth rate, feed intake, protein efficiency ratio, and intestinal digestive enzymatic activities (amylase, trypsin, and lipase) tended to decline with increasing FM replacement levels (P > 0.05). Dietary SCM substitution significantly influenced dry matter content in muscle, and crude protein and lipid contents in liver (P < 0.05). ADCs for dry matter, protein, lipid, energy, and most amino acids showed no significant differences between the control and SCM25 group, but tended to decline with replacement levels over 25%. Higher SCM substitution (50–100%) caused karyopyknosis and necrosis in liver, but intestinal histology did not show noticeable pathological changes. The present study indicated that FM could be replaced by 25% of SCM, without significant adverse growth performance, feed utilization, and histology of crucian carp.     

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 Dietary pH Adjustment on the Utilization of Supplemental Methionine and Lysine by Juvenile Common Carp,Cyprinus carpio

An 8‐wk feeding trial was conducted to compare the effect of dietary pH on the utilization of crystalline amino acid (CAA, 0.2% dl ‐methionine and 0.4% l ‐lysine·HCl) by juvenile common carp, Cyprinus carpio. A basal diet (diet C) with protein derived mostly from fish meal and soybean meal was supplemented with CAA without pH adjustment (diet CAA, pH 6.2) and with pH adjusted to 7.0 and 8.0 (diets CAA pH 7.0, CAA pH 8.0, respectively). Supplementation of CAA, regardless of dietary pH adjustment, significantly increased the feed intake and weight gain, and the latter was significantly higher in fish fed diets CAA pH 7.0 or CAA pH 8.0 compared to fish fed diet CAA. The intestinal protease activity was significantly higher in fish fed diets CAA pH 7.0 or CAA pH 8.0 compared to fish fed diet CAA. Apparent digestibility of dry matter and crude protein in diets CAA pH 7.0 and CAA pH 8.0 were significantly higher than those in diet C. Dietary supplementation of CAA generally decreased the plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, but markedly increased the hepatic AST and ALT activities. Compared to fish fed diet CAA, fish fed diets CAA pH 7.0 or CAA pH 8.0 showed higher hepatic AST activity but slightly lower plasma ammonia level. These results indicate that adjusting the pH of CAA‐supplemented diets to neutral or slightly alkaline resulted in improving the CAA utilization by common carp.     

Evaluation of Poultry By‐product Meal in Commercial Diets for Hybrid Striped Bass,Morone chrysops ♀ × Morone saxatilis ♂, in Pond Production

The efficacy of replacing fish meal with petfood‐grade poultry by‐product meal (PBM) on an ideal protein basis in commercial diets for hybrid striped bass (HSB) was evaluated under production conditions in pond culture. A generic production diet (GEN) for HSB was formulated to contain 45% protein, 12% lipid, and 3.7 kcal/kg. Protein in the generic diet was supplied by a mix of animal and plant sources typically used by the industry that included more than 20% select menhaden fish meal and less than 10% PBM. A positive control diet (GEN + AA) was formulated by supplementing the generic diet with feed‐grade Met and Lys to match the level of those amino acids in HSB muscle at 40% digestible protein. Substitution diets were formulated by replacing 35, 70, or 100% of fish meal in the GEN diet with PBM on a digestible protein basis and then supplementing with Met and Lys (designated 35PBM, 70PBM, and 100PBM, respectively) as needed to maintain concentrations equal to those in the GEN + AA diet. Diet formulation and extrusion were conducted by a commercial mill, and all diets met or exceeded known nutritional requirements for HSB. Twenty 0.10‐ha ponds (4 ponds/diet) were randomly stocked with juvenile HSB (76 ± 10 g; mean ± SD) at a density of 7400/ha and fed for 600 d (October 2004 to May 2006). Diets were fed once daily to apparent satiation to a maximum of 95 kg feed/ha. Total weight and number of fish in each pond were determined at harvest. Weight distributions in each pond were estimated by selecting every 15th fish during harvest. Subsets of ten fish from each of these samples were selected randomly for the determination of body composition and nutrient and energy retention. The availability of indispensable amino acids as well as ammonia production from the commercial test diets were determined in separate tank trials. Most production characteristics were not statistically different (P > 0.10) among dietary treatments. Distributions of individual fish weights from each of the ponds were not affected by poultry by‐product level in the diet. Multivariate analysis of body compositional indices grouped diets into two clusters composed of GEN, GEN + AA, 35PBM vs. 70PBM, and 100PBM mainly because fish fed the 70PBM and 100PBM diets had greater (P = 0.001) body fat (visceral somatic indices) than fish fed the other diets. Ammonia production in tanks was not different among diets and peaked 6–8 h after feeding when fish were fed at 1.5% of body weight; ammonia‐N excretion ranged from 197 to 212 mg/kg/d and 18.5–21.5% of nitrogen intake. Some imbalances in the levels and ratios of selected amino acids to Lys were found in the diets containing higher amounts of PBM and were attributed to a lack of accurate availability coefficients during formulation for some dietary proteins. These imbalances in essential amino acids may have been the predominant factor in the somewhat fattier fish observed fed diets containing the two highest levels of PBM. Nevertheless, these results from fish stocked at commercial densities and raised to market size in ponds suggest that formulating diets on an available amino acid basis for all protein sources while balancing limiting amino acids, particularly Met, Lys, Thr, and Trp, on an ideal protein basis will yield significant improvements in HSB performance when fed commercial diets in which all fish meal is replaced with PBM.     

Effect of dietary protein reduction with synthetic amino acids supplementation on growth performance,digestibility, and body composition of juvenile Pacific white shrimp, <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

Two experiments were conducted to evaluate the effect of lowering crude protein level and fish-meal inclusion rate by using commercially available synthetic amino acid supplements in practical diets on the growth performance of Litopenaeus vannamei. In experiment 1, three diets were formulated to assess whether 50% of fish meal could be replaced by soybean meal with synthetic amino acid supplementation. Diet 1 was formulated as the normal control with 20% fish meal and 36% crude protein; diet 2 was the negative control with 34% crude protein and half of the fish meal was replaced with soybean meal; and diet 3 was similar to diet 2 but was supplemented with amino acids to ensure the level of lysine, methionine plus cystine, and threonine similar to that in the diet 1. After a 70-day feeding trial, weight gain and specific growth rate of shrimps fed diet 2 were significantly lower than those fed diet 3, and numerically lower than those fed diet 1. Feed intake of shrimps fed diet 3 was significantly higher than those fed diets 1 and 2. There were no significant differences in feed conversion ratio among shrimps fed different diets. In experiment 2, four diets were prepared with diet 1 as the normal control with 41.26% crude protein, diets 2–4 were formulated to contain 39.81, 38.40, and 35.52% of crude protein with synthetic amino acids were added to simulate the amino acid levels of the diet 1. After a 70-day feeding trial, it was found that reducing dietary crude protein from 41.26 to 35.52% did not affect weight gain or feed conversion ratio. The survival of crude protein 35.52% treatment was significantly lower than other treatments. No difference was observed in body protein, lipid composition, and apparent digestibility coefficient among dietary treatments. Results of this study suggested that dietary crude protein could be reduced from 41.26 to 35.52% in the diets of L. vannamei as long as synthetic amino acids were supplemented.     

Molecular Characterization and Dietary Regulation of the AlaSerCys Transporter 2 in Grass Carp,Ctenopharyngodon idella

AlaSerCys Transporter 2 (ASCT2), a glutamine/amino acid transporter, plays an important role in the absorption of neutral amino acids. In this study, we cloned the full‐length cDNA of ASCT2 from grass carp, Ctenopharyngodon idella, which encodes a 541‐amino‐acid protein. Phylogenetic analysis revealed that the ASCT2 sequence of grass carp clustered with the ASCT2 from Danio rerio. ASCT2 mRNA was differentially expressed in different tissues, with a gradient expression from high to low in tissues of the liver, gill, muscle, midgut, hypophysis, hindgut, kidney, heart, foregut, brain, spleen, and gonad. Meanwhile, the quantitative real‐time polymerase chain reaction results showed that 22% crude protein diets could significantly stimulate ASCT2 gene expression. In addition, ASCT2 was expressed in higher quantities in the soybean meal group than in the fishmeal group. Furthermore, 7.5 g/kg glutamine and 2.5 g/kg glutamine dipeptide remarkably improved the expression of ASCT2. These results suggested that ASCT2 expression is regulated by the dietary protein levels and sources, as well as appropriate concentration of glutamine and glutamine dipeptide additives.     

Effects of dietary cellulase addition on growth performance,nutrient digestibility and digestive enzyme activities of juvenile crucian carp Carassius auratus

This study was conducted to determine the effects of dietary cellulase addition on improving the nutritive value of Chlorella for juvenile crucian carp Carassius auratus (initial body weight: 2.99 ± 0.02 g, mean ± SEM). Five isonitrogenous and isoenergetic experimental diets were formulated to contain 0.0 (control), 0.5, 1.0, 1.5 and 2.0 g kg^?1 cellulase, respectively. Each experimental diet was randomly assigned to triplicate groups with 25 juvenile fish per fibreglass tank for 8 weeks. The results showed that weight gain, specific growth rate, feed intake and the trypsin activity in the anterior intestine increased with increasing dietary cellulase to 1.5 g kg^?1 and then declined with further addition. However, the mRNA expression levels of Mrf4 and Myf5, the apparent digestibility coefficients for dry matter, protein, energy and the majority of amino acids, and the activity of lipase in the anterior intestine were highest in fish fed the 1.0 g kg^?1 cellulase diet, and then tended to decline with further cellulase supplementation. In conclusion, the optimal dietary cellulase supplementation level was 1.0–1.5 g kg^?1, which can improve growth performance, digestive activities and nutrient digestibility in crucian carp.     

Fishmeal can be totally replaced by a mixture of rapeseed meal and Chlorella meal in diets for crucian carp (Carassius auratus gibelio)

This study was conducted to investigate the effects of dietary fishmeal (FM) replacement by a mixture of rapeseed meal and Chlorella meal (RCM) on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities and intestinal histology of crucian carp Carassius auratus gibelioi. Five isonitrogenous diets were formulated to replace 0% (RCM0), 25% (RCM25), 50% (RCM50), 75% (RCM75), and 100% (RCM100) of protein from fishmeal with RCM respectively. Each experimental diet was randomly assigned to triplicate groups with 25 juvenile fish (initial body weight: 1.77 ± 0.04 g) per fibreglass tank for 6 weeks. With increasing substitution levels, weight gain rate, specific growth rate, feed intake and protein efficiency ratio increased, but feed conversion rate decreased. Dietary RCM substitution improved lipid content of muscle, but had no significant effect on other proximate composition of muscle and liver. ADCs of dry matter, protein, lipid, energy and the majority of amino acids increased with increasing substitution level, and digestive enzyme activities (amylase, trypsin and lipase) in intestine showed the similar trend with ADCs. Dietary RCM substitution had no significant adverse effect on intestinal histology. This study indicated that FM protein could be completely replaced by mixed protein sources (RCM) in crucian carp diets.     

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.     

Effects of Neutral Phytase Supplementation on Biochemical Parameters in Grass Carp,Ctenopharyngodon idellus,and Gibel Carp,Carassius auratus gibelio,Fed Different Levels of Monocalcium Phosphate

Two 8‐wk studies were conducted to evaluate the effects of neutral phytase supplementation on hemato‐biochemical status, liver biochemical parameter, and intestinal digestive enzyme activity of grass carp, Ctenopharyngodon idellus, and gibel carp, Carassius auratus gibelio, fed with different levels of monocalcium phosphate (MCP). The control diet was prepared with 2% MCP but without phytase (P2.0). The other three experimental diets were prepared with the addition of 1.5, 1.0, and 0.5% MCP, respectively, when supplemented with 500 U/kg neutral phytase in each diet and designated as PP1.5, PP1.0, and PP0.5, respectively. The results indicated that the serum alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) activities, as well as the albumin (ALB) content were increased in grass carp (P < 0.05) and gibel carp (P > 0.05) fed with phytase‐supplemented diets. Meanwhile, the serum cholesterol, high‐density lipoprotein, and total protein contents of the two species of fish were increased in comparison to the control. In addition, dietary phytase inclusion did not significantly affect hepatic ALP, ALT, and AST activities in the two species of carp fed with different levels of MCP. Amylase activity increased in foregut and hindgut of both species when fed with the phytase‐supplemented diets while lipase activity was reduced in the foregut and hindgut in both fish. This study suggests that neutral phytase supplementation increases serum ALP, ALT, and AST activities but does not notably affect these enzyme activities in the liver of the two species of carp when fed different levels of MCP. On the other hand, amylase activity increased while lipase activity was reduced in the intestine of the species of carp fed with phytase‐supplemented diets.     

Senegalese sole juveniles (Solea senegalensis Kaup, 1858) grow equally well on diets devoid of fish meal provided the dietary amino acids are balanced

A growth trial was conducted with the aim of developing a practical, environmentally sustainable and cost-effective plant-protein-based diet for Senegalese sole juveniles without compromising growth or protein deposition. A reference diet contained fish meal as the main protein source (F45, containing 37% fish meal and 45% of the dietary protein being from marine sources) and four plant-protein diets either containing 5% (F15) or no fishmeal (F5). The F15 diet also contained 5% hydrolysed protein (CPSP) and 5% squid meal while the F5 contained 2% CPSP and 3% squid meal. The rest of the protein derived from a blend of soybean meal, corn and wheat gluten. Thus, the plant-protein fraction in these test diets ranged from 70–80%. The plant-based diets were supplemented either with a mixture of all indispensable amino acids (IAA) (F15 + IAA, F5 + IAA) or only with lysine (F15 + Lys, F5 + Lys). Triplicate groups of 18 fish of 9.5 g were fed by automatic feeders that distributed 8 meals over 24 h, for a period of 12 weeks.At the end of the experiment mean body weight more than tripled in all treatments (32.8 to 42.7 g). Sole fed with either F15 + Lys (33.3 g) or F5 + Lys (32.8 g) grew significantly less than all the other treatments. Protein productive value (PPV) was significantly lower in sole fed with F5 + Lys (0.30) than in all other treatments (0.34 to 0.37) while F5 + Lys (0.23) energy productive value (EPV) just differed significantly from fish fed with F45 (0.38). Moreover, protein gain (P gain) was significantly higher in sole fed with diet supplemented with all IAA (F15 + IAA and F5 + IAA) than those fed with diet with only lysine added (F15 + Lys and F5 + Lys) and a strong positive correlation between P gain and methionine (Met) intake was found (P = 0.00002).Dietary fish meal protein can be totally replaced by a mixture of plant-protein sources without any adverse effects on growth, feed or protein utilization provided the dietary amino acids are balanced. The test diet F5 + IAA seems a good alternative to use in Senegalese sole production when the main objective is to substitute an increasingly scarce ingredient – fish meal – without compromising fish performance. Moreover, for large-scale production feeds the F15 + Lys putatively supplemented with Met, Thr and Arg would be recommended.     

Effects of partial substitution of dietary fish meal by fermented soybean meal on growth performance,amino acid and biochemical parameters of juvenile black sea bream Acanthopagrus schlegeli

A feeding trial was conducted to evaluate the effect of replacing fish meal protein with fermented soybean meal (FSM) on the growth performance, feed utilization, amino acid profile, body composition, morphological parameters, activity of antioxidant and digestive enzymes of black sea bream (Acanthopagrus schlegeli) juvenile. Five isonitrogenic and isolipidic diets were prepared with levels of 0 (control), 80, 160, 240 and 320 g kg^?1 FSM. Triplicate groups (40 fish per tank) of juvenile black sea bream with initial weight of 1.17 ± 0.04 g were hand‐fed to visual satiation at three meals per day for 8 weeks. The fish fed diets containing different levels of FSM had no significant differences regarding survival and specific growth rate compared with control group. Feed and protein efficiency ratios of fish fed diet containing 320 g kg^?1 FSM were significantly lower than those of control group. Daily feed intake and daily protein intake of fish fed diet containing 240–320 g kg^?1 were significantly higher than those of control group. Hepatosomatic index and condition factor of fish were not affected by different dietary FSM level. Fish fed diets containing 240–320 g kg^?1 FSM had significantly higher visceral somatic index than control group. Whole body proximate and amino acid compositions of fish were not affected by dietary FSM level. The activity of digestive enzymes in the intestine was not affected by dietary FSM level. The activity of glutathione peroxidase in liver was significantly higher for fish fed the diet containing 160 g kg^?1 FSM compared with control group. This study showed that up to 40% fish meal in the diets of juvenile black sea bream could be replaced by fermented soybean meal with supplementation of methionine, lysine and taurine.     

Fishmeal can be totally replaced by plant protein blend at two protein levels in diets of juvenile Siberian sturgeon,Acipenser baerii Brandt

An 8‐week growth trial was conducted to evaluate the effects of a plant protein blend (PPB, comprised of soybean meal and wheat gluten meal) as fishmeal (FM) substitute on growth, nitrogen (N) and phosphorus (P) balance in Siberian sturgeon, Acipenser baerii Brandt. Two control diets were formulated to contain two protein levels (400 and 360 g kg^?1). At each protein level, FM was totally replaced by PPB with supplement of crystalline essential amino acids and mono‐calcium phosphate. Growth performance was not affected by dietary protein sources and protein levels. Fish fed the low‐protein diets had higher FI than that of the high protein groups, while fish fed the FM‐based diets had higher FI than that of fish fed the PPB‐based diets. N/P intake of fish showed linear relationship with total N/P loss. The productive P value was significantly affected by dietary protein sources, but no significant effects were shown on productive N value. The results suggest that Siberian sturgeon fed total plant‐based diets with balance of EAA could maintain normal growth performance and reduce total P excretion both at 360 and 400 g kg^?1 protein levels.     

Nutritional evaluation of some Bangladeshi oilseed meals as partial substitutes for fish meal in the diet of common carp, Cyprinus carpio L.

Abstract. Three oilseed meals (mustard, linseed and sesame) of Bangladeshi origin were evaluated as fish meal substitutes in diets of common carp, Cyprinus carpio L. These oilseed meals were included in the diet at various levels (25, 50 and 75% of dietary protein) and the response of fish fed these diets was compared to fish fed a fish meal based control diet (40% protein). On the basis of observed growth rate, food conversion ratio, protein efficiency ratio and apparent net protein utilization, the control diet produced significantly (P< 0.05) the best growth performance. Growth responses were significantly affected by both type and inclusion level of oilseed protein. Of the oilseed proteins tested, the 25% mustard protein and 25% linseed protein diets produced significantly (P< 0.05) better growth performances than higher inclusion levels tested. Apparent protein digestibilities (APDs) for all diets were fairly high, ranging from 77.72 to 89.8O%. In general, APD values decreased with increasing plant protein. Fish fed diets containing higher levels of oilseed protein had significantly (P< 0.05) higher carcass moisture and lower carcass lipid contents. Fish fed 50% mustard protein had histological abnormalities in liver and thyroid tissues. Results are discussed with respect to dietary levels of essential amino acid and anti-nutritional factors.     

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.     

The potential of land animal protein ingredients to replace fish meal in diets for cuneate drum, Nibea miichthioides, is affected by dietary protein level

A net pen experiment was carried out to examine the effect of dietary protein level on the potential of land animal protein ingredients as fish meal substitutes in practical diets for cuneate drum Nibea miichthioides. Two isocaloric basal (control) diets were formulated to contain 400 g kg^?1 herring meal but two different digestible protein (DP) levels (400 versus 350 g kg^?1). At each DP level, dietary fish meal level was reduced from 400 to 280, 200, 80 and 0 g kg^?1 by incorporating a blend that comprised of 600 g kg^?1 poultry by‐products meal (PBM), 200 g kg^?1 meat and bone meal (MBM), 100 g kg^?1 feather meal (FEM) and 100 g kg^?1 blood meal (BLM). Cuneate drum fingerling (initial weight 42 g fish^?1) were fed the test diets for 8 weeks. Fish fed the test diets exhibited similar feed intake. Final body weight, feed conversion ratio and nitrogen retention efficiency was not significantly different between fish fed the basal diets containing 350 and 400 g kg^?1 DP. Weight gain decreased linearly with the reduction of dietary fish meal level at the 350 g kg^?1 DP level, but did not decrease with the reduction of dietary fish meal level at the 400 g kg^?1 DP level. Results of the present study suggest that fish meal in cuneate drum diets can be completely replaced with the blend of PBM, MBM, FEM and BLM at the 400 g kg^?1 DP level, based on a mechanism that excessive dietary protein compensate lower contents of bio‐available essential amino acid in the land animal protein ingredients relative to fish meal.     

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.