Growth and economic analysis of freshwater prawn,Macrobrachium rosenbergii (de Man), produced with feeds substituting sunflower cake for fish meal,soya bean meal and mustard oil cake

A feeding trial with Macrobrachium rosenbergii was carried out to test the effectiveness of sunflower cake (SFC) as a replacement for conventional protein sources. Four isonitrogenous (~30% crude protein) and isocaloric (388–402 kcal) diets were formulated. Diet‐1 was a control made with conventional ingredients including fish meal, soya bean meal and mustard oil cake. Diet‐2, Diet‐3 and Diet‐4 were made with 30%, 40% and 50% SFC, respectively, replacing the usual protein sources used in Diet‐1. After 100 days, diets with SFC inclusion showed favourable growth and economic performance trends compared to control diet‐1, but without significant differences (p > .05). Better production (572.89 ± 62.99 kg/ha) was observed with Diet‐4 followed by Diet‐2, Diet‐3 and Diet‐1. Diet‐4 revealed the best feed conversion ratio (2.56 ± 0.24), specific growth rate (1.18 ± 0.05) and protein efficiency ratio (1.14 ± 0.10) among these diets. Whole carcass composition analysis revealed highest crude protein (18.19%) and lipid (4.43%) content in prawns fed Diet‐3 followed by Diet‐4. Highest total income, gross margin and benefit cost ratio (BCR) per hectare from prawns were US$5,759, US$2,623 and 1.84, respectively, found in Diet‐4. This study demonstrates that 30%–50% inclusion of SFC has favourable impacts on productivity and profitability compared with controls, with 50% SFC inclusion as the most cost‐effective diet for prawns without apparent compromise in growth, flesh quality or economics. The performances of the diets suggest that SFC may be a suitable substitute for fishmeal, soya bean meal and mustard oil cake in prawn feed. The effectiveness of higher SFC concentrations should also be investigated.     

In vivo and in vitro protein digestibility and growth performance of animal and no‐conventional plant ingredients for river prawn Macrobrachium americanum (Caridea: Palaemonidae)

The objectives of this study were to evaluate the effects of non‐traditional plant and animal protein for river prawn M. americanum on in vivo versus in vitro digestibility in addition to growth performance. In this study, ten ingredients were used: coconut meal, jackfruit meal, soybean meal, poultry by‐product meal, squid meal and fish meal. In vivo studies were conducted using the zeolite marker method, whereas in vitro digestibility was determined by the pH‐stat method using river prawn hepatopancreas enzymes. According to the findings, river prawns digest animals more efficiently than plant ingredients, with squid and fish meal showing a tendency of higher values. Fish meal (53.66%), squid meal (48.52%) and jackfruit meal (42.21%) were found to have a digestibility greater than 40% in in vivo and in vitro methods, thus suggesting that they are the best ingredients used in this study. This also validates their inclusion in practical diets. The correlation of digestibility of in vivo and in vitro was low (R² = .6749). The highest daily weight gain was recorded in the diets containing jackfruit, coconut and squid. Given that the potential of no‐conventional plant ingredients available regionally was significantly higher, this underscores the need to conduct further research to validate their inclusion in practical diets.     

Digestibility of nutrients and energy in ingredients for bullfrogs during different phases of development

The ability of frogs to digest dietary nutrients changes with growth, with the animals becoming more or less demanding. The objective of this study was to determine the apparent digestibility coefficients of protein, energy and ether extract of 14 ingredients used in bullfrog diets (spray‐dried blood meal, hydrolysed feather meal, poultry by‐product meal, red blood cell concentrate, tilapia by‐product meal, sardine fishmeal, salmon fishmeal, meat and bone meal, corn gluten meal, soybean meal, corn, wheat bran, soy protein concentrate and soybean oil). A total of 2,325 bullfrogs (Lithobates catesbeianus) in different phases of development were used: early phase (mean weight of 30–50 g), growth phase (80–110 g) and finishing phase (150–200 g). Faeces were collected using the method of dissection. Marked differences in digestibility of the ingredients were observed between the different phases of frog development. Among the ingredients studied, salmon fishmeal and corn gluten meal showed good utilization of the protein (78.9% and 86.7%, respectively) and energy fraction (89.4% and 83.3%, respectively). The salmon fishmeal, poultry by‐product meal, sardine fishmeal, soy protein concentrate, wheat bran and soybean oil exhibited good ether extract utilization (81.2%–92.8%), recommending their use in bullfrog diets.     

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

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

Evaluation of ultra‐low gossypol cottonseed and regular glandless cottonseed meals as dietary protein and lipid sources for Litopenaeus vannamei reared under zero‐exchange conditions

The current study evaluated transgenic cotton lines with normal levels of gossypol/terpenoids in the vegetative and floral tissues, but with ultra‐low gossypol in the seeds as a replacement for glandless cottonseed meal (GCSM) and fishmeal. A 64‐day growth trial evaluated the ability of cottonseed meals from a natural glandless cotton variety/mutant, two transgenic Ultra‐low Gossypol Cottonseed (ULGCS) lines, a non‐transgenic parental control and a commercial variety, to replace 355 g kg^?1 fishmeal in a diet containing 350 g kg^?1 crude protein. Juvenile Litopenaeus vannamei (1.48 ± 0.29 g) were stocked (40 shrimp m^?3) with six replicates. No significant differences were found between all formulated diets in terms of final weight, survival and feed conversion ratio. The commercial cottonseed variety displayed a significantly lower feed efficiency ratio and protein efficiency ratio than one of the ULGCS diets. These results suggest that GCSM and/or transgenic ULGCS meals can be used to replace fishmeal in commercial shrimp diets.     

Aspergillus niger fermented plant protein mix as a potential substitute for fishmeal in the diet of Penaeus vannamei (Boone, 1931)

A 45‐day feeding trial was conducted to evaluate the utilization of fermented plant protein mix (FPPM) as a fishmeal substitute in the diet of Penaeus vannamei. Six isonitrogenous and isolipidic diets were formulated by substituting fishmeal at 0% (control), 50%, 60%, 70%, 80% and 90% (FR‐0, FR‐50, FR‐60, FR‐70, FR‐80 and FR‐90, respectively) using FPPM. Shrimps fed with diets FR‐50, FR‐60 and FR‐70 had no significant difference in weight gain (173.22%–178.07%) with the control group (179.50%). However, the broken‐line regression indicated that 70.8% fishmeal could be substituted by FPPM. The trend of digestibility was reflected in growth performance. Survival had no significant difference among the treatments. Fishmeal substitution had significant (p < .05) variations in protease and amylase activity, but not in lipase. Except lipid, other body composition was not affected due to dietary change. A decrease (p < .05) in haemolymph total protein, cholesterol and triglycerides was observed to increase in fishmeal substitution. A higher fishmeal substitution (FR‐90) had significantly (p < .05) lower total haemocyte count and the reverse was true for phenoloxidase. Results conclude that a combination of fermented ingredients would be more effective rather using alone in shrimp feed, with a great potential in reducing the pressure on fishmeal.     

Substituting fishmeal with extruded soybean meal in diets did not affect the growth performance,hepatic enzyme activities,but hypoxia tolerance of Dolly Varden (Salvelinus malma) juveniles

Extruded soybean meal (ESBM) showed increased digestibility of crude protein, amino acids and fat, better oil retention capacities, attenuated anti‐nutrient factor effects and improved its nutritive value compared with raw soybean meal, indicating a promising application prospects for ESBM in fish culture. This study aimed to evaluate the effects of substituting fishmeal with ESBM on growth performance, hepatic antioxidant capacity and the resistance to hypoxia stress on juvenile Dolly Varden (Salvelinus malma). Five hundred and forty fish were randomly assigned to six groups fed with iso‐nitrogenous and iso‐energetic diets with ESBM for replacement of 0% (control), 10% (G1), 20% (G2), 30% (G3), 40% (G4) and 50% (G5) fishmeal. After an 81‐day feeding trial, groups fed ESBM substituted diets (G2 to G5) showed no significant differences in survival rates, final body weights, weight gain rates, feed conversion ratios, specific growth rates, hepatosomatic indexes and condition factors with the control group (G0), reflecting normal food intake and growth performance. The hepatic enzyme activities of total antioxidant capacity, catalase and superoxide dismutase were not affected by ESBM substituted diets, showing no harmful effects on ROS eliminating abilities. Hepatic HSP70 expression levels had increased 1.3 times for G5 group, reflecting a less tolerance to hypoxia for fish fed diets with high substituting level of ESBM. In conclusion, replacing, despite 50%, fishmeal with ESBM in diets had no detrimental effects on growth performance and hepatic enzyme activities, but lowering the hypoxia tolerance of juvenile Dolly Varden (Salvelinus malma).     

Innovative Egg Custard Formulation Reduced Rearing Period and Improved Survival of Giant Freshwater Prawn,Macrobrachium rosenbergii,Larvae

This study was conducted to determine the performance of new egg custard formula to replace Artemia sp. on the growth and survival of the giant freshwater prawn, Macrobrachium rosenbergii, larvae. Five experimental diets were tested with triplicate treatments: ART (Artemia sp.), ART‐MIX (Artemia sp. + egg custard MIX: a mixture of shrimp, squid, and bivalve meal‐based egg custard, with palm oil), ART‐PBM (Artemia sp. + PBM, poultry byproduct meal‐based egg custard with fish oil), egg custard MIX only, and egg custard PBM only. All experimental diets were tested after 9 d (stage VI) of feeding Artemia sp. to prawn larvae. The stocking density was set at 100 larvae/L in a clear water tank culture system. Results indicated that the highest survival was recorded in the treatment of ART‐PBM (46.07 ± 0.84%) and the lowest was in the MIX treatment (8.87 ± 0.51%). ART‐PBM and ART‐MIX diets successfully reduced the rearing period and improved survival from larval to postlarval stage by 19 and 65%, respectively, compared with the ART diet. However, the use of MIX and PBM alone increased the rearing period up to 11%. The feeding regime of ART‐PBM and ART‐MIX has provided nutritional advantages and can be successfully practiced in the hatchery of M. rosenbergii larvae. The innovative approach of using PBM and palm oil in the egg custard formulation in this study can provide prawn hatchery operators with more options in terms of dietary ingredients and cost‐effective solutions.     

A review of nutritional biology and dietary requirements of redclaw crayfish Cherax quadricarinatus (von Martens 1868)

Redclaw crayfish (Cherax quadricarinatus, von Martens 1868) is a freshwater decapod crustacean with a number of biological and commercial attributes that make it an excellent aquaculture species. The redclaw aquaculture industry has been growing rapidly since the mid‐1980s in tropical and subtropical regions of the world. Redclaw aquaculture is mostly in extensive pond systems, but interest in developing more intensive systems is increasing. To support continued intensification, development of high‐quality practical diet formulations and information about redclaw nutrition requirements are necessary. A number of studies have determined optimum dietary protein and lipid requirements for juvenile redclaw. However, there is limited information on essential amino acid and fatty acid requirements. Several studies report the presence of various digestive enzymes that have been linked to the ability of the species to digest a wide range of dietary components. Furthermore, as in many other aquaculture species, there is a need to replace fishmeal with other protein sources. A number of studies explored the possibility of replacing fish meal with various terrestrial plant sources of protein and lipids and showed that redclaw can be offered diets containing low‐cost, plant‐based ingredients without compromising survival, growth and, to a certain extent, reproduction. Formulated diets containing less expensive, plant ‐ based ingredients will contribute to a more profitable and environmentally sustainable redclaw aquaculture industry. Finally, there is also a paucity of information on vitamin and mineral requirements of redclaw and little information on nutrient requirements of broodstock. For the redclaw aquaculture industry to thrive, we need to have a better understanding of nutrient requirements at all life stages.     

Development of plant‐based diets and the evaluation of dietary attractants for juvenile Florida pompano,Trachinotus carolinus L.

Sustainable and profitable commercial aquaculture production of marine fish species is dependent on the development of sustainable protein sources as substitutes for expensive animal meals such as fishmeal (FM). Previous Florida pompano Trachinotus carolinus studies have indicated that poultry by‐product meal (PBM) and meat and bone meal can be used to produce a FM‐free diet if suitable levels of nutrients (such as taurine) are included in the diets. In this study, we attempted to develop an all‐plant protein diet by removing the animal proteins in practical diets for pompano by substituting back select ingredients. A series of eight FM‐free diets were formulated, four systematically replaced soybean meal (SBM) with soy protein concentrate (SPC) and four replaced PBM with SPC. Based on the results, there is no clear disadvantage to the use of SPC as a replacement for SBM. However, the complete removal of PBM resulted in reduced performance. Two additional growth trials were conducted to supplement additional amino acids including glycine, valine and histidine, a proprietary chemical attractant mix, fish protein concentrate and squid hydrolysate to improve the growth of pompano when fed all‐plant protein diets. The only improvement in performance occurred with the squid hydrolysate. These results demonstrate that using soybean meal, soy protein concentrate and corn gluten meal as the primary protein sources, a plant‐based feed formulation can be developed, but the removal of all animal proteins is not yet feasible.     

Effect of selected feed meals and starches on diet digestibility in the mud crab,Scylla serrata

The present study examined the capacity of the mud crab, Scylla serrata to digest experimental diets that contained different animal and plant‐based feed meals or different levels or types of starch. The apparent dry matter digestibility (ADMD) coefficients for all feed meals tested in the first part of this study, except meat meal, were similar (78–88%). Crude protein digestibility (ACPD) coefficients for all feed meals were relatively high, with values ranging from 86% to 96%. Cotton seed meal, poultry meal, canola meal, fishmeal, soybean meal and lupin meal had similar gross energy digestibility (AGED) values (P>0.05) ranging from 84% to 89%. In the second part of this study, the impact of selected starches on the digestibility of fishmeal‐based formulated diets was assessed. The apparent starch digestibility (ASD) of wheat starch decreased significantly as the inclusion level was increased from 15% to 60%, however, there was no significant effect on ACPD values. At a 30% inclusion level, the ASD of diets containing different starches decreased in the order corn>wheat>potato=rice. Moreover, ACPD values were significantly higher (P<0.05) in the diets containing corn or rice starch than in those containing wheat or potato starches.     

Evaluation of practical diets containing various terrestrial protein sources on survival and growth parameters of redclaw crayfish Cherax quadricarinatus

Redclaw aquaculture has developed at a rapid pace during the past few years, yet no specialized diet for the species has been developed. The present study was designed to evaluate whether soybean‐based diets containing either fishmeal (FM), poultry by‐product meal (PBM), ground peameal (GPM) or distillers dried grains with solubles (DDGS) meal as a protein source are suitable for redclaw aquaculture. Juvenile redclaw crayfish Cherax quadricarinatus (0.125±0.025 g) were stocked into 20 rectangular tanks at a stocking density of 12.5 m^?2 for 8 weeks. Crayfish in four replicate tanks were maintained on one of five diets formulated to contain 35% crude protein and 7.1% lipids. Each 100 g of diet contained 25 g of protein from soybean meal (SBM) and 10 g of protein from the alternative protein sources mentioned above. A fifth treatment that did not receive feed was included to account for growth from natural productivity. There were no significant differences in survival (86–90%), growth (3.84–4.98 g animal^?1) or feed conversion ratio (2.10–2.79) of crayfish among the four treatments (P>0.05). Survival and growth of crayfish in the treatment that received no supplementary feed were significantly less than those in treatments offered experimental diets. Results of the present experiment suggest that SBM‐based diets with PBM, FM, DDGS or GPM have similar effects on growth performance and survival of juvenile redclaw, C. quadricarinatus.     

Partial and total replacement of fishmeal by a blend of animal and plant proteins in diets for Seriola dumerili: Effects on performance and nutrient efficiency

A 154‐day trial was performed to assess the use of an alternative protein blend (corn gluten, krill and meat meal) as a substitute for fishmeal in diets for juvenile yellowtail, using four isolipidic (140 g/kg) and isoenergetic diets (24 MJ/kg) with the same digestible protein content (50%). The control diet was FM100, without replacement, and in FM66, FM33 and FM0, fishmeal was replaced at 33 g/kg, 66 g/kg and 100 g/kg, respectively. At the end of the experiment, no differences in growth parameters were observed. Fish fed the FM0 diet exhibited the lowest survival (23%). This high mortality may be due to different factors, such as a dietary amino acid imbalance or some antinutrient factors contained in the alternative ingredients. Feed intake, feed conversion ratio, digestible protein intake and protein efficiency ratio were similar in all diets. However, digestible energy intake and protein efficiency retention were lowest in fish fed the FM0 diet. Apparent digestibility coefficients for protein, energy and amino acids diminished as a substitution for fishmeal increased. Significant differences were observed in the diet whole‐fish body profile amino acid retention (AAR) ratio for the seven essential amino acids. In summary, total fishmeal replacement by the blend assayed was not feasible for yellowtail. The FM66 diet resulted in good growth, high survival and good nutrient efficiency.     

Growth and immune response of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae fed diets containing Chlorella vulgaris (Beijerinck)

A 50‐day growth trial was conducted to evaluate the efficacy of Chlorella vulgaris (Beijerinck) as an ingredient in the diets of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae (PL30). Immune response (total haemocyte count and prophenoloxidase activity) was also assessed by subjecting postlarvae to a challenge test against Aeromonas hydrophila (Chester) for 14 days. Iso‐nitrogenous and iso‐lipidic test diets were prepared using a fishmeal‐based‐positive control diet (D0) and four basal diets with inclusion levels of 2% (D2), 4% (D4), 6% (D6) and 8% (D8) C. vulgaris. Postlarvae of M. rosenbergii were randomly stocked (mean initial body weight of 0.19 ± 0.02 g) in 30‐L tanks in three replicates per dietary treatment for evaluation of growth performance. Another set of postlarvae (mean initial body weight of 1.25 ± 0.02 g) was randomly distributed in 95‐L tanks in three replicates per dietary treatment for the assessment of immune response. Results showed that specific growth rate was significantly higher (P < 0.05) in postlarvae fed D4 and D6. Variations in values for carcass protein, lipid, moisture and ash were also evident. Postlarvae fed diets with Chlorella showed increased prophenol oxidase activity and total haemocyte counts. Moreover, survival rate after challenge with A. hydrophila was significantly increased (P < 0.05). Inclusion of C. vulgaris in diets enhanced immune response and resistance of M. rosenbergii postlarvae against A. hydrophila infection.     

Fungus,Aspergillus niger,fermented groundnut oil cake as a fishmeal alternative in the diet of Penaeus vannamei

Commercial de‐fatted groundnut oil cake (GNC) fermented with the fungus Aspergillus niger was evaluated as a fishmeal alternative in the diet of Penaeus vannamei. A 45‐day growth trail was performed using nine iso‐nitrogenous and iso‐lipidic diets. Untreated/fermented GNC was included at the rate of 0 (control), 25, 50, 75 and 100 g/kg by replacing fishmeal (w/w). Each diet was randomly assigned to triplicate group of 20 shrimps (initial weight of 3.09 ± 0.03 g). Results revealed that shrimp fed with diets having untreated GNC up to 50 g/kg has no significant difference in growth, whereas the inclusion level was enhanced to 100 g/kg with fermented GNC with no deleterious effect. The negative linear trend was found for SGR with increasing the inclusion of both untreated and fermented GNC. The feed and protein efficiency measures, viz. feed conversion ratio, protein efficiency ratio and apparent protein utilization, were better in shrimps fed with diets having fermented GNC than those fed the respective level of untreated GNC. The broken‐line analysis indicated that the inclusion of 72.5 g/kg fermented GNC showed the best FCR. No significant difference was observed in survival (86.67%–96.67%) between the dietary treatments. There was a significant difference in ether extract of shrimp between the treatments, whereas other parameters were not affected. Haemolymph indices showed a significant difference in total protein, glucose, cholesterol and triglycerides between control and test diets. The results conclude fermented GNC, which can be better than untreated one in the diet of shrimp.     

Apparent digestibility coefficients of animal and plant feed ingredients for juvenile Pseudobagrus ussuriensis

A study was conducted to determine apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, gross energy, phosphorus and amino acids (AAs) from Peruvian fish meal (PFM), native fish meal (NFM), meat bone meal (MBM), dried daphnia meal (DDM), soybean meal (SBM), full‐fat soybean (FSBM), cottonseed meals (CSM), rapeseed meal (RSM) and corn gluten meal (CGM) for Pseudobagrus ussuriensis (7.8 ± 0.06 g). Test diets were formulated to contain a 70:30 mixture of reference diet to test ingredient with chromic oxide (5 g kg^–1) serving as the inert marker. ADCs of DM ranged from 49.94% (CGM) to 87.11% (PFM), the highest ADCs of DM were observed in PFM and the lowest was found in CGM. ADCs of CP in the test ingredients ranged from 74.92% (CGM) to 93.41% (SBM). ADCs of crude lipid ranged from 51.80% (CGM) to 94.07% (PFM) for fish. ADCs of energy ranged from 56.42% (CGM) to 90.09% (PFM). ADCs of phosphorus ranged from 21.81% (CSM) to 65.70% (PFM). AA availability for the test ingredients followed a similar pattern to ADCs of CP, in which values for PFM, NFM and MBM were generally higher (p < .05) than those of other protein ingredients. Among all plant meals, the AA availability values in SBM were higher (p < .05) than those in CGM, CSM and RSM. The availability of most AAs in CGM was the lowest (p < .05) among all tested ingredients. In conclusion, PFM and NFM are good sources of available protein and AAs. When fishmeal supply is limited, MBM and DDM are substitutes for fishmeal reduction in P. ussuriensis diets; at the same time, SBM and FSBM are also very acceptable protein feedstuffs. However, CSM, RSM and CGM could not be used at high levels in P. ussuriensis diets because of their inferior digestibilities.     

Identification of a putative cellulase gene in the giant freshwater prawn,Macrobrachium rosenbergii (De Man, 1879)

Nutrition plays an important role in the development of all organisms and in particular that of farmed aquatic species where costs associated with feed can often exceed 60% of total production costs. Crustacean species in addition, have the added metabolic requirement for regular moulting to allow normal growth and this requires large amounts of energy in the form of sugars (glucose). The current study explored the capacity of the giant freshwater prawn to produce endogenous cellulose‐degrading enzymes capable of extracting nutrients (simple sugars) from plant sources in formulated feeds used in the prawn aquaculture industry. We identified a putative cellulase cDNA fragment in the target organism of 1576 base pairs in length of non‐microbial origin that after protein modelling exhibited a TM‐score of 0.916 with a described cellulase reported from another crustacean species. The functional role of cellulase enzymes is to hydrolyse cellulose to glucose and the fragment identified in GFP was highly expressed in the hepatopancreas, the site of primary food digestion and absorption in crustaceans. Hepatopancreatic tissue from Macrobrachium rosenbergii also showed active digestion of cellulose to glucose following an endoglucanase assay. Cellulase gene(s) are present in the genomes of many invertebrate taxa and play an active role in the conversion of cellulose to available energy. Identification and characterization of endogenous cellulase gene(s) in giant freshwater prawn can assist development of the culture industry because the findings confirm that potentially greater levels of low‐cost plant‐material could be included in artificial formulated diets in the future without necessarily compromising individual growth performance. Ultimately, this development may contribute to more efficient, cost‐effective production systems for freshwater prawn culture stocks that meet the animal's basic nutritional requirements and that also support good individual growth rates.     

Digestibility of selected feedstuffs in subadult Caspian great sturgeon,Huso huso using settlement faecal collection and stripping methods

Apparent crude protein (ADC_CP), crude fat (ADC_CF) and gross energy (ADC_GE) digestibility coefficients of several typical and novel feedstuffs were determined to be employed in the formulated diets of subadult beluga (17.70 ± 0.234 kg) diets via two faecal collection methods of settlement (SFCM) and stripping (StM). The tested feedstuffs included three fish meals, three terrestrial animal by‐products, three plant protein concentrates, nine high‐protein plant meals and three low plant protein meals. ADC_CP values varied in different fish meals ranging from 89.5% for Mexican sardine meal to 93.2% for anchovy meal with SFCM. ADC_CP values for plant protein concentrates ranged from 82.8% for wheat gluten meal to 92% for soy protein with SFCM. ADC_CP ranged from 37.2% for whole wheat to 75.6% for spirulina meal with SFCM. ADC_GE was lower in low‐protein plant meals (64.1%) in comparison to high‐protein plant meals (70.2%). Fish meals showed the highest ADC_CF values. A significant (P < 0.05) quadratic regression relation (r² = 0.92) was observed among in vivo ADC_CP of five feedstuff classes fed to beluga and in vitro ADC_CP. The differences among ADC values appear to be significantly related to the effects of feedstuffs and therefore diet and faecal collection methods.     

Effects of fishmeal replacement by feather meal in practical diets for juvenile crayfish (Pacifastacus leniusculus Dana,Astacidae)

The aim of this study was to evaluate different replacement levels of fishmeal (FM) by feather meal (FeM) on survival and growth of juvenile crayfish (Pacifastacus leniusculus). An 80‐day experiment was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets (500 g kg^?1 protein) differing in the level of replacement of FM protein by FeM protein were prepared: 0% (control diet), 15% (8.2% dietary FeM), 25% (13.7% dietary FeM) or 35% (19.2% dietary FeM). Each diet was tested on grouped or individually isolated crayfish. Crayfish fed the control diet or 15% replacement achieved the highest survival (average of grouped and isolated: 88.2%) and growth (grouped and isolated: 13.58 mm carapace length, 523.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 1.11). Final growth of isolated crayfish was significantly higher than that of grouped crayfish for all diets. This study provides the first data on the substitution possibilities of FM by FeM in diets for freshwater crayfish. An 8.2% of FeM (15% replacement of FM protein) can be included in extruded diets for juvenile P. leniusculus during the first 80 days of intensive rearing without impairing growth or feed conversion.     

Nutritional assessment of Australian canola meals. II. Evaluation of the influence of the canola oil extraction method on the protein value of canola meals fed to the red seabream (Pagrus auratus, Paulin)

This study examined the biological value of expeller‐ and solvent‐extracted canola meals when included in the diets of juvenile red seabream. Notably, the test and reference diets in this study were prepared to be protein (300 g kg^?1 DM) and energy (16.5 MJ kg^?1 DM) limiting. Test diets were prepared, in which canola meal provided either 20%, 40% or 60% of the total dietary digestible protein. To minimize the influence of compensatory feed intake, all diets were pair‐fed to the fish on restricted basis. Positive and negative controls were also included as treatments in the study to demonstrate that the diets were protein limiting and also to demonstrate the relative value of the highest inclusion levels of each test ingredient. The canola meals, either expeller‐ or solvent‐extracted, were found to be nutritionally useful in diets for red seabream. Both ingredients were of similar value to that of the soybean meal when included on an equivalent digestible protein basis. No significant differences in weight gain, survival, FCR, N retention, energy retention or the apparent biological value of the N content were observed among any of the groups receiving the test or reference diets. A few significant differences were observed among some of the test and reference diets with regard to the apparent biological value of their energy content, although no consistent pattern was evident. The positive control treatment supported significantly superior growth and food utilization by the fish relative to all other treatments. The negative control treatment resulted in significantly poorer growth and food utilization by the fish relative to all other treatments. On a relative basis, there were no declines in fish performance between the highest inclusion levels of the expeller‐ and solvent‐extracted canola meals or the soybean meal. Hence, the fish in this study obtained equivalent nutritional value from these ingredients, on a digestible basis, to that of the fishmeal in the reference diet.