Partial substitution of fish meal and full-fat soya bean meal with wheat gluten and influence of lysine supplementation in diets for rainbow trout, Oncorhynchus mykiss (Walbaum)

A 65-day study was undertaken to evaluate the utilization of lysine-supplemented wheat gluten meal as a protein source for rainbow trout, Oncorhynchus mykiss (Walbaum). The performance of the trout fed wheat gluten was compared to that of trout where protein was principally supplied using fish meal and full-fat soyabean meal. Six isonitrogenous diets (approximately 45% crude protein) were formulated. Thus, the reference diet (FS) was based on fish meal and full-fat soya bean meal while a further five diets were formulated with a mixture of wheat gluten and wheat middlings used to isonitrogenously replace approximately 75% and 57% of the full-fat soya and fish meal respectively. Crystalline l -lysine representing 0.00%, 0.29%, 0.58%, 0.87% and 1.16% of the complete diet was then added to the wheat-gluten-based diets. Optimal performance in terms of weight gain and apparent net protein utilization was achieved by the fish fed a wheat-gluten-based diet supplemented with lysine (0.58%) yielding a digestible lysine level of 1.9% of the complete feed. Within the range of supplements provided, lysine digestibility was high. However, at the highest levels of supplemental lysine the relationship between uptake and supplement level was not linear. Additionally, arginine digestibility was not affected by the level of lysine supplementation. However, amongst the wheat-gluten-based diets, optimal performance was associated with a lysine: arginine ratio of 1.1: 1. Despite a lysine: arginine ratio of approximately 1.1: 1, the overall performance of the fish fed the fish-meal-soya-based reference diet was poorer than expected. The results are discussed with respect to optimal patterns of gross and digestible amino acids, lysine-arginine antagonism and the possible relationship between antinutritional factors and the poor performance of the fish fed the fish-meal-soya-based reference diet.     

Using Near Infrared Reflectance Spectroscopy (NIRS) to predict the protein and energy digestibility of lupin kernel meals when fed to rainbow trout,Oncorhynchus mykiss

This study examined the potential of using near infrared spectroscopy (NIRS) to predict the nutrient composition, energy density and the digestible protein and digestible energy values of lupin kernel meals when fed to rainbow trout. A series of 136 lupin kernel meals were assessed for their protein and energy digestibilities using the diet‐substitution approach in a series of 10 experiments over a 6‐year period from 2002 to 2008. Two reference diets were also included in each experiment. Minimal variance in the digestibility parameters of both reference diets was observed among the experiments ensuring that there was a high degree of robustness in the across‐experiment evaluations. The same lupin kernel meal samples were also scanned using a diode array near infrared spectrophotometer (DA‐NIRS). The spectra obtained by the DA‐NIRS were chemometrically calibrated against both the chemical composition and the digestible value data using multivariate analysis software. The cross validation tests used in this study provide a valid indication of the potential to predict the nutrient composition, energy value and digestible protein and energy values of the lupin kernel meals as used in diets for rainbow trout. That the standard errors of cross validation (SECV) of the parameters investigated were generally commensurate with the cross trial variation seen in the reference sample indicating robust calibrations for the two target parameters of digestible protein and digestible energy. Therefore this study demonstrates that within one raw material type that not only does significant variability in the digestible value of the raw materials exist, but that it is possible to use NIRS technology to provide rapid estimates of the digestible value of those raw materials in near real‐time.     

The influence of dehulling efficiency on the digestible value of lupin (Lupinus angustifolius) kernel meal when fed to rainbow trout (Oncorhynchus mykiss)

A single batch of Lupinus angustifolius seed was processed to produce a seed meal and dehulled to produce a pure kernel meal. A series of blends were prepared from the seed and kernel meals. The digestible values of these pure and a series of blended meals were compared when fed to rainbow trout using the diet‐substitution method (700 g kg⁻¹ reference: 300 g kg⁻¹ test ingredient). Improvements were observed for each of dry matter, energy and crude protein digestibilities with increasing dehulling efficiency. The relationship between dry matter digestibility and kernel meal proportion was linear and is described by the equation: y = 0.2147x + 40.929. Dry matter digestibility for the 100% kernel meal was 59.8%. The relationship between crude protein digestibility and kernel meal proportion was curvilinear and is described by the equation: y = −0.0019x² + 0.3948x + 81.9143. Crude protein digestibility for the 100% kernel meal was 102%. The relationship between energy digestibility and kernel meal proportion was linear and is described by the equation: y = 0.158x + 48.77. Energy digestibility for the 100% kernel meal was 65.1%. The findings of this study demonstrate that there are significant benefits from using kernel meals over seed meals.     

A comparison of the growth performance of rainbow trout (Oncorhynchus mykiss) when fed soybean,narrow‐leaf or yellow lupin meals in extruded diets

This study compared the effect of increasing dietary inclusion of soybean, narrow‐leaf lupin or yellow lupin kernel meals when fed to rainbow trout. Each meal was formulated into a test diet to create a series of inclusion levels of 0, 100, 200, 300 and 400 g kg^?1. Each diet was formulated to the same digestible protein and energy specifications. The diets were fed to apparent satiety to 30.0 ± 0.71 g rainbow trout for 28 days. After this period, fish in the reference (0 g kg^?1) treatment attained a weight of 93.2 g. Growth of the fish among the treatments was observed to be improved by the addition of either variety of lupin meal. In contrast, growth of fish fed the soybean meal was equivalent to that of the 0 g kg^?1 fish meal reference, but was poorer at the 400 g kg^?1 inclusion level. Feed intake with the lupin meals was marginally improved with lupin inclusion, but at the higher soybean meal inclusions, feed intake was reduced relative to the fish meal reference diet. The inclusion of the different grains also had significant effects on the physical properties of the pellets.     

Evaluation of the influence of Lupinus angustifolius kernel meal on dietary nutrient and energy utilization efficiency by rainbow trout (Oncorhynchus mykiss)

This study examined the utilization efficiencies of three diets when fed to rainbow trout in a 28‐day growth study. Each of the diets was fed at one of three ration levels, and an additional starved treatment was also included. The diets differed by an increasing concentration of lupin (Lupinus angustifolius cv. Myallie) kernel meal (MKM) inclusion. Two lupin kernel meal inclusion levels of 15% (MKM15%) and 30% (MKM30%) were studied. The diets were formulated to equivalent digestible protein and energy specifications based upon the predetermined digestibility values for each of the ingredients used. There were no significant differences in digestible protein level among the diets. However, a significantly higher level of digestible energy of both MKM diets was measured, as well as a significantly higher level of digestible phosphorus in the MKM30% diet. No significant differences between the diets were observed with respect the utilization of dietary digestible energy. Over the full data range, the energy utilization efficiency was described by the linear equation of; y = 0.747x ? 26.174, R² = 0.985. Efficiency of protein utilization over lower digestible protein intake levels was also linear (y = 0.599x ? 0.142, R² = 0.905), but over the full range was better described by a nonlinear function. The comparison of the three diets in this study shows that the dietary inclusion of lupin kernel had no significant effect on the gain of either protein or lipid energy relative to protein or lipid energy intake, respectively. Protein energy use efficiency constants varied depending on the feed intake level, but were not significantly affected by diet type. The efficiency of use of lipid energy for lipid energy retention was also not affected by diet type. The findings of this study demonstrate that the inclusion of lupin kernel meal, at up to 30% of the diet, does not affect the ability of rainbow trout to utilize the dietary digestible protein and energy of diet in which it is included.     

Apparent protein and energy digestibility of common and alternative feed ingredients by Atlantic cod, Gadus morhua (Linnaeus, 1758)

Studies were conducted with Atlantic cod, Gadus morhua (L.), to determine the apparent digestibility coefficients (ADCs) of protein and energy and the digestible energy (DE) content in feed ingredients widely available in Canada. We also tested the assumption of “independency” used in digestibility studies. The feed ingredients included two fish meals (herring, anchovy), three crustacean by-product meals (whole krill, crab, shrimp), two animal by-product meals (poultry by-product, hydrolyzed feather), six oilseed meals (soybean, soy protein concentrate, soy protein isolate, canola, canola protein concentrate, flaxseed), two pulse meals (white lupin, pea protein concentrate) and two cereal grain meals (corn gluten, wheat gluten). Protein ADCs were high for wheat gluten meal (99.9%), soy protein concentrate (98.6%), soy protein isolate (97.4%), whole krill meal (96.3%), herring meal (93.3%), soybean meal (92.3%), anchovy meal (92.2%), pea protein concentrate (89.8%), white lupin meal (89.7%), crab meal (89.4%), canola protein concentrate (88.8%) and corn gluten meal (86.3%); mid-range for poultry by-product meal (80.2%) and canola meal (76.0%); and low for shrimp meal (66.7%), hydrolyzed feather meal (62.4%) and flaxseed meal (50.2-55.0%). Energy ADC was high for whole krill meal (96.3%), wheat gluten meal (95.4%), soy protein concentrate (94.9%), herring meal (92.8%), soy protein isolate (92.1%), soybean meal (88.1%) and anchovy meal (86.4%); mid-range for canola protein concentrate (83.3%), corn gluten meal (82.7%), crab meal (82.4%), pea protein concentrate (76.7%) and white lupin meal (75.3%); and low for poultry by-product meal (71.0%), canola meal (60.6%), hydrolyzed feather meal (58.9%), shrimp meal (41.4%) and flaxseed meal (21.2-37.4%). From the protein ADC data, results clearly showed that the basal diet and test feed ingredients were digested independently of one another in nearly all cases, the only exceptions being for those diets containing test ingredients of very high (> 99%, wheat gluten) or very low (< 67%, hydrolyzed feather and flaxseed) protein ADCs. In the case of DE, the basal diet and test feed ingredients were digested independently in all test diets without exception.     

Assessing the implications of variability in the digestible protein and energy value of lupin kernel meals when fed to rainbow trout, Oncorhynchus mykiss

A series of studies were designed to examine the degree of variability in the digestibility of protein and energy from lupin (Lupinus angustifolius) kernel meals when fed to rainbow trout (Oncorhynchus mykiss) and the potential implications of this variability. The digestibility of protein and energy from 10 different varieties of lupin kernel meal was assessed where the test ingredient comprised 30% of each test diet. Digesta was collected using faecal stripping techniques. Digestible protein value ranged from 331 to 508 g/kg DM and digestible energy values ranged from 10.6 to 13.3 MJ/kg DM. To examine the implications of variability in digestible protein and energy value, two lupin kernel meals from the extremes of the protein digestibility range (Lupin-1: AD_N ~ 70% and Lupin-2: AD_N ~ 100%) were chosen for assessment in two growth studies. Soybean meal and a reference diet with fishmeal as the only protein source were also included in the study. In the first growth experiment the test ingredients were included at equal concentrations (40%) in protein-limiting diets (350 g protein/kg DM) and fed at either of two ration levels (restricted and satiety). Diets were formulated on a crude basis so as to place the test variable on the variability in digestible protein value of the diets. In the restricted-fed treatments growth of fish fed the reference diet was highest, but not significantly better than lupin-H. Growth of fish fed the lupin-L diet was significantly poorer than both the reference and lupin-H diets, but not poorer than the soybean diet. The growth responses observed from this experiment clearly showed that the differences in feed intake and/or digestible protein value could be demonstrated in terms of significant differences in growth outcomes. In a second growth study high-nutrient dense extruded diets (400 g protein/kg and 23.5 MJ/kg) were prepared with a more practical level of 25% inclusion of the same test materials. Again the diets were formulated on crude basis so as to place the test variable on the variability in digestible protein and energy value of the diets. Growth of fish restrictively fed the lupin-H diet was highest, but not significantly better than the soybean, reference or lupin-L treatments restrictively fed. Growth of fish satietal fed the soybean diet was significantly poorer than the reference and lupin-H diets, but not compared to the lupin-L diet. The growth responses observed from this experiment showed that the differences in digestible protein and energy value could not be demonstrated in terms of significant differences in growth outcomes, and that feed intake variability and excess nutrient supply masked the effect of this variability; particularly at the satietal feed intake levels.     

Apparent digestibility of Asian carp‐ and common carp‐derived fish meals in feeds for hybrid striped bass Morone saxatilis ♀ × M. chrysops ♂ and rainbow trout Oncorhynchus mykiss

Apparent digestibility coefficients (ADCs) of nutrients (crude protein, amino acids, crude lipid, fatty acids, and minerals) were determined for fish meals derived from menhaden, Asian carp (combination of silver and bighead carps), and common carp in feeds for hybrid striped bass and rainbow trout. Extruded test diets were formulated to contain a 70 : 30 mixture of reference diet and test ingredient with yttrium oxide (1 g kg^?1) serving as the inert marker. Diets were randomly assigned to triplicate tanks and fish were fed once per day at 2% body weight. Fecal samples were collected by manual stripping. The ADCs were calculated according to standard procedures. The composition and digestibility of Asian carp and common carp meals was broadly similar to menhaden meal. Protein digestibility ranged from 86.5% (Asian carp meal) to 93.1% (common carp meal). Lipid was highly digestible with ADCs >100% for all ingredients. Although the Asian carp meal was less digestible than the other two fish meals, it was still a highly digestible ingredient. Our data suggest that fish meals derived from Asian or common carp would be valuable feedstuffs in diets for hybrid striped bass, rainbow trout, and possibly other cultured fishes.     

Feeding high inclusion of whole grain white lupin (Lupinus albus) to rainbow trout (Oncorhynchus mykiss): effects on growth,nutrient digestibility,liver and intestine histology and muscle fatty acid composition

The effect of dietary inclusion of whole grain white lupin (Lupinus albus) on growth performance, histology, muscle fatty acid composition and nutrient digestibility was investigated in an 11‐week growth and a 4‐week digestibility trial with rainbow trout (initial body weight of 54.0 ± 6.2 and 181.9 ± 3.4 g respectively). Four experimental extruded diets were formulated to contain 0%, 30%, 40% and 50% of whole grain lupin and fed to triplicate groups of fish twice a day until apparent satiation. Faeces were collected daily from each digestibility tank by decantation. No significant trends were observed with respect to growth, feed utilization, apparent digestibility coefficients or whole‐body composition (P>0.05). Conversely, increasing levels of dietary lupin led to significant decreases in the Hepatosomatic index (R²=0.75, P<0.05) and slight lipid infiltration into hepatocytes and enterocytes. Muscle fatty acid compositions were slightly affected by the dietary treatment. Polynomial regression of dietary inclusion of lupin and muscle fatty acid concentrations showed an increase in C18:1n‐9, C18:2n‐6 and C18:3n‐3 and a decrease in C20:5n‐3 with increasing dietary lupin level. These results demonstrated that whole grain lupin can be included up to 50% in commercial rainbow trout diets without negative effects.     

Effects of extrusion processing of feed ingredients on apparent digestibility coefficients of nutrients for rainbow trout (Oncorhynchus mykiss)

An experiment was conducted to evaluate the effects of extrusion processing on apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude fat, energy and minerals in soya bean meal (SBM), barley, corn gluten meal and whole wheat, using rainbow trout Oncorhynchus mykiss as the test species. In addition, availabilities of amino acids were also determined in SBM. Feed ingredients were preconditioned at 89–93 °C and then extruded using a Wenger X‐85 extruder. Nonextruded ingredients were used as is, meaning that they were not preconditioned. The extruded and nonextruded ingredients were mixed with a casein–gelatin reference diet at 3 : 7 ratio prior to determination of ADC values. A total of 135 trout (initial mean body weight 223.4 ± 12.7 g) were stocked into nine 140‐L fibreglass digestibility tanks with 15 fish per tank. Individual tanks were assigned randomly to each of eight diets made from the four ingredients (extruded and nonextruded) plus the reference diet. After faeces were collected in the first week, the diets were switched among tanks, and faeces were collected again after 5‐day acclimation period in the second week. Yttrium oxide was used as the inert marker. Results showed that extrusion processing significantly improved ADCs of dry matter, crude fat and gross energy, and reduced ADCs of crude protein, phosphorus, copper, iron and zinc. Results also showed that the effects of extrusion processing on chemical composition and ADCs of nutrients depended on the ingredients. It is recommended that trace minerals such as copper, iron and zinc be supplemented by an additional 10–20% when rainbow trout diets are extruded because of their reduced bioavailability in plant meal‐based feed ingredients.     

Variability in the composition of lupin (Lupinus angustifolius) meals influences their digestible nutrient and energy value when fed to rainbow trout (Oncorhynchus mykiss)

Over a series of seven separate experiments 76 different lupin (Lupinus angustifolius) meals were assessed for their digestible dry matter, protein, amino acid and energy characteristics when fed to rainbow trout. Two reference diets (a common basal diet and a reference lupin meal) were also included in each experiment. Minimal variance in the digestibility parameters of both reference diets was observed among the experiments ensuring that there was a high degree of robustness in the across-experiment evaluations. Using simple and multiple-regression techniques, principal diet and ingredient composition factors affecting diet and ingredient digestibilities and ingredient digestible values were explored within the dataset. Using simple linear regression, it was shown that nitrogen digestibility of the lupin meals was negatively influenced by ingredient lignin content, but positively affected ingredient protein (N × 6.25) content. The energy digestibility of the lupin meals was positively affected by a range of compositional features including protein, sum of amino acids and negatively affected by carbohydrate content. The digestible nutrient and energy content of the meals reflected the combined effects of both ingredient digestibilities and ingredient composition. The digestible nitrogen content of the lupin meals was positively affected by protein (N × 6.25), sum of amino acids and energy content, but was negatively affected by lignin and carbohydrate content. The digestible sum of amino acids was also positively affected by protein, sum of amino acids, but only negatively affected by carbohydrate content, not lignin content. The digestible energy content of the lupin meals was also positively affected by protein, sum of amino acids and their own energy density, but only negatively affected by carbohydrate content. Multiple linear regression modelling supported that together ingredient protein and lignin content were the strongest predictors of digestible protein value, explaining close to 60% of the variability in this parameter. Discrete reassessment of these relationships using non-linear analysis methods provided a stronger interpretation of the ingredient composition effects. In recognition of this, a functional model including terms for ingredient protein and lignin content on the digestible protein value was defined. This study demonstrates that within one raw material type that not only does significant variability in the digestible value of the raw materials exist, but that it is possible to identify compositional features of that raw material that are intrinsically influencing their own digestible value.     

Growth performance,haematological and serum biochemical profiles in rainbow trout (Oncorhynchus mykiss) fed diets with varying levels of lupin (Lupinus albus) meal

A feeding experiment was conducted to study the response of rainbow trout juveniles fed different levels of lupin meal in diets for rainbow trout juveniles. Very limited information is available on the relationship between dietary lupin meal in rainbow trout health status. Therefore, this study aimed to determine the effects of lupin meal inclusion levels (0%, 15%, 30%, 45%, and 60%) on growth performance and health status of rainbow trout juveniles. The experimental diets (LM₀, LM₁₅, LM₃₀, LM₄₅, and LM₆₀) were formulated iso‐nitrogenous (41% crude protein) and iso‐calorific (18% crude lipid). The fish were fed twice a day. As a result, the best growth performance was observed in fish fed with LM₁₅ and LM₃₀ diets. No significant differences were detected among experimental groups in terms of body compositions. The haematological values showed significantly (p < 0.05) lower heamatocrit and mean cellular volume (MCV) in the group of LM₆₀ compared with the other groups. For the other haematological parameters such as haemoglobin, red blood cell and mean cellular haemoglobin studied in the present study no significant differences were observed (p < 0.05). The lupin meal included groups showed significant reduction in total protein (TPROT), triglyceride (TROG), cholesterol (CHOL), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) compared with the control group (p < 0.05). The inclusion of lupin meal did not cause any changes in glucose (GLU), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) between the treatment groups (p < 0.05). In conclusion, lupin meal might be used in rainbow trout diets up to 30% without any malnutrition effect on growth performance, haemotological and serum biochemical parameters.     

Evaluation of the feed value of a transgenic strain of the narrow‐leaf lupin (Lupinus angustifolius) in the diet of the marine fish,Pagrus auratus

This study assessed the nutritional and biological value of a noncommercial, transgenic line of the Australian sweet lupin, Lupinus angustifolius, (cv. Warrah), produced to increase the methionine content of the seed. An initial experiment demonstrated that differences in the methionine content of the transgenic and nontransgenic control lupins had no apparent influence on the growth of juvenile red seabream fed practical diets. Re‐evaluation of the nutritional characteristics of the lupin meals with subsequent digestibility studies allowed the determination of the digestible value of the protein and energy content of each of the varieties. The digestible protein content of either variety was similar, however significant differences in the digestible energy value of each variety existed (56.3% cf. 64.0%). This re‐evaluation of the nutritional value of the genetically manipulated (GM) and non‐GM lupin varieties enabled the reformulation of diets on a digestible protein and energy basis. A second growth trial was undertaken using sub‐satietal pair‐feeding regimes, with the experiment also involving protein‐restrictive diets to allow expression of the differences in the methionine content of the transgenic and nontransgenic lupin meals. A significant benefit of the enhanced methionine level in the transgenic lupin was observed. It is argued that in the high‐protein fish diets used, the importance of amino acid composition is relatively limited. Economic modelling of the potential value of the increased methionine in the transgenic lupin suggests that this will have limited benefit for aquaculture industries, and that greater value would be attributable to higher protein and energy levels in ingredients.     

Apparent digestibility of protein, energy, and amino acids in some selected feed ingredients for pacu Piaractus mesopotamicus

The apparent digestibility coefficients (ADCs) of amino acids (AA), protein, and energy in six feed ingredients (Brazilian fish meal, soybean meal, corn gluten meal, alcoholic yeast, corn, and wheat bran) we evaluated for pacu juveniles. In general, all ingredients showed high digestibility values for all AA, and differences among ADCs of individual amino acid were detected ( P  < 0.01). Corn gluten, soybean, and fish meals had the highest ADCs of AA. The ADCs of protein in fish meal, yeast, and corn gluten meal should not be used as AA digestibility indicators, because those showed differences up to 6.7% between the ADCs of protein and AA. All ingredients had lower ADCs of energy than corn gluten meal ( P  < 0.01). Lysine was the first limiting amino acid in fish meal, corn gluten meal, wheat bran, and corn, and the second limiting amino acid in soybean meal, as methionine was the first limiting amino acid in soybean meal and yeast. However, the soybean meal was the best quality protein source, as it had the highest digestible essential amino acid index. This demonstrated that digestible amino acid values can be used to formulate practical diets for pacu, preventing potential deficiencies or excess that might cause environmental and economic losses.     

Evaluation of Yellow Lupin Lupinus luteus Meal as an Alternative Protein Resource in Diets for Sea-Cage Reared Rainbow Trout Oncorhynchus mykiss

The performance of sea-water reared rainbow trout Oncorhynchus mykiss fed three isonitrogenous and iso-energetic diets based on either fishmeal, solvent-extracted soybean meal or yellow lupin ( L luteus cv. Wodjil) kernel meal was evaluated. Over the course of a 10-wk study, the fastest growing fish were those fed the diet containing 50% yellow lupin kernel meal (YLM), which grew from 83.6 ± 0.7 g to 322.8 ± 3.2 g (mean ± SEM). This was not significantly faster than growth of fish fed the diet based on 50% solvent-extracted soybean meal (SBM), though it was significantly ( P < 0.05) faster than the growth of fish fed the fishmeal based diet (FSM). Growth of fish fed the experimental diets was comparable to growth of fish fed a range of commercial diets as a reference. Survival of fish fed the FSM diet was poorest of all the treatments (47.4%), though this was only significantly poorer than that of fish fed the YLM diet (88.9%). Feed intake was highest by fish fed the YLM diet (5.58 g/d) and lowest for fish fed the FSM diet (336 g/d). Reasons for these differences in feed intake were not clear, though they may be related to different levels of buoyancy and palatability among the diets. Feed conversion rate (FCR) was consistent between treatments at about 1.6:1, though given that this study was a sea-cage based experiment it is likely that considerable unaccounted feed losses occurred, thereby inflating the feed conversion value. Sensory evaluation of fish fed the three test treatments showed no overall difference in the acceptability of the fish, further supporting that solvent-extracted soybean meal and yellow lupin kernel meal both have considerable potential to replace fishmeal as a protein resource in diets for rainbow trout.     

Digestive function and intestinal integrity in Atlantic salmon (Salmo salar) fed kernel meals and protein concentrates made from yellow or narrow-leafed lupins

This study assessed the effects of yellow lupin (Lupinus luteus) and narrow-leafed lupin (L. angustifolius) kernel meals and protein concentrates on the gastrointestinal integrity, capacity for digestive hydrolysis, and digestibility of nutrients in Atlantic salmon. A basal diet (FM) was made from fish meal, wheat, and fish oil. Six additional diets were formulated by replacing 30% of the FM diet with lupin kernel meal made from L. l. cv. Wodjil (LKM), L. a. cv. Belara (BKM), and L. a. cv. Myallie (MKM), lupin protein concentrates made from the same L. l. (LPC) and L. a. cv. M (MPC), or extracted soybean meal (SBM). All diets were extruded. Each diet was fed to three groups of 176 g salmon kept in 1 m² tanks with 5.6 °C saltwater for 3 weeks prior to sampling of blood, intestinal organs, digesta, and faeces. Inclusion of lupin meals in the diets resulted in harder and more condensed feed particles. Ulcer-like lesions were observed in the stomach of fish from all feeding groups, and this was worsened by lupin in the diet, but did not appear to be pellet hardness related. No consistent altered morphology was observed in the distal intestine (DI) of fish fed the FM and lupin diets, while the DI of fish fed SBM showed consistent and typical soybean meal-induced pathomorphological changes. Plasma cholesterol was higher when feeding MKM and LKM than when feeding FM, MPC, and LPC, with intermediate levels when feeding BKM and SBM. Feeding LKM and LPC resulted in a higher weight of the GIT when related to body weight. Trypsin activity and bile acid concentration were generally higher in digesta from the pyloric (PI) and mid (MI) intestine when feeding FM and lupin diets than when feeding SBM, while the opposite was seen for trypsin activity in digesta from DI. There were no effects of diet on leucine aminopeptidase (LAP) and maltase activity in PI and MI, but in DI the activity of these brush border enzymes were significantly lowered when feeding SBM. SBM in the diet resulted in watery faeces and lowered apparent digestibility of lipid, but this was not observed when feeding the lupin diets. To conclude, the tested lupin kernel meals and protein concentrates did not alter the intestinal function in Atlantic salmon when included at 30% of the diet. Dietary lupin was, however, involved in the worsening of ulcer-like gastric lesions.     

Evaluation of the nutritional value of prototype lupin protein concentrates when fed to rainbow trout (Oncorhynchus mykiss)

This study examines the palatability and discrete nutritional evaluation of some prototype lupin protein concentrates (PC) when fed to rainbow trout. Products were developed from both Lupinus angustifolius and Lupinus luteus kernel meals with an increase in protein of 415 g/kg DM to 690 g/kg DM for L. angustifolius and 545 g/kg DM to 750 g/kg DM for L. luteus, respectively. This study completes a three-phase approach to evaluating the nutritional value of these products. The digestibility of energy, nitrogen, phosphorus and organic matter were determined in earlier studies using the diet substitution approach. The apparent digestibility of the energy from the L. angustifolius PC and the L. luteus PC along with the apparent protein digestibility were used to formulate two series of experimental diets to examine both the palatability and discrete nutritional value of the products. Serial inclusion of either PC at 0%, 10%, 20%, 30% and 40% into a typical salmonid diet specification allowed an examination of the palatability of each product. Additional negative controls, based on the 0% diets with inclusion of sulfamerazine sodium, were included in the experiment to demonstrate the capacity of the experiment to detect significant palatability issues. No significant effects of inclusion of either PC on any fish performance criteria, such as feed intake or growth, were identified. In contrast, significant reductions in feed intake and consequently growth were observed from fish fed either of the negative controls. This experiment demonstrated that each PC was highly palatable at inclusion levels up to and including 40% of the diet. Using a protein-limited-restrictively-fed experimental approach the discrete nutritional utilisation of each PC was defined. Growth of fish fed the PC treatments was not significantly different to that of the 0% reference diet. Two control diets with substitutions of cellulose to an equivalent inclusion level to that of the PC have provided an indication of the net benefit of the test ingredients. This experiment demonstrated that each PC provided equivalent nutritional value to the fish at either of the two inclusion levels (20% and 40%) evaluated. These PCs differed in their viscosity and gelling properties which may allow feed manufacturers the opportunity to manipulate the physical attributes of their feeds. Together, these studies clearly show that the prototype PCs have substantial potential as a prospective feed ingredient for the aquaculture sector.     

Utilization of combined extruded soybean and corn gluten meals as feed ingredients for juvenile rainbow trout,Oncorhynchus mykiss diet

In this study, feeding experiment and subsequent digestibility trial were performed to investigate the utilization of extruded soybean meal (SBM) and corn gluten meal (CGM) as feed ingredients for juvenile rainbow trout. Plant ingredients have undergone extrusion at low temperature (100°C, LT) or high temperature (150°C, HT) for 30 s. Four isonitrogenous (44%, crude protein) and isolipidic (14%, crude lipid) diets were formulated. Control diet is fishmeal based while a combined (1:1) non‐extruded SBM and CGM for NE diet, LT SBM and LT CGM for LT diet and HT SBM and HT CGM for HT diet. Two hundred forty rainbow trout juveniles (7.8 g average body weight) were randomly divided into 12 rectangular 60 L glass aquaria and offered four different diets in triplicate. Fish were fed at satiation twice a day, six days a week for 12 weeks. Phosphorus in phytic acid level of extruded ingredients decreased through extrusion cooking. Final weight, weight gain, SGR and PER of fish fed HT diet were significantly (p < .05) higher than those fed with NE diet. Apparent digestibility coefficient for protein of LT and HT diets is significantly higher than of NE diet. The results of this study demonstrated that HT extruded SBM and CGM are suitable feed ingredients for rainbow trout diet without compromising fish growth, feed utilization and fish body composition.     

Nutritional assessment of Australian canola meals. I. Evaluation of canola oil extraction method and meal processing conditions on the digestible value of canola meals fed to the red seabream (Pagrus auratus, Paulin)

This study assessed the nutrient and energy digestibility of a variety of canola protein products that were produced by processing canola meal under different conditions, using the red seabream, Pagrus auratus. The test canola protein products included solvent‐extracted canola meal, expeller‐extracted canola meal alone or subjected to one of two different heat treatments (120 or 150°C for 30 min), and expeller meal further processed to produce a canola protein concentrate (CPC). Solvent‐extracted soybean meal was also included in the study as a reference ingredient. Daily feed intake and blood thyroid hormone levels over the experimental period were also examined. The total digestible protein content of the expeller‐ and solvent‐extracted canola meals was 356 and 358 g per kg dry matter (g kg DM^?1) respectively. The total digestible energy content of the expeller‐ and solvent‐extracted canola meals was 14.23 and 8.60 MJ kg^?1 respectively. The organic matter digestibilities of the solvent‐extracted canola meal were poorer than noted for the expeller‐ and solvent‐extracted soybean meal. Notably, the two sources of canola meals used in this study (solvent and expeller meals) did not cause problems with declining feed intakes or changes to blood levels of thyroid hormones when included in the diets of the fish at a 30% level, and the diets were fed over a 3‐week period. The preparation of a CPC resulted in gains in total digestible energy, but a reduction in the amount of total digestible protein, relative to the expeller canola meal from which it was produced. However, the protein concentrating process marginally reduced the relative digestible value of the protein content. Heating expeller meal at 120 or 150°C for 30 min resulted in progressive reductions of all nutrient and energy digestibilities.     

Growth performance and expression of immune‐regulatory genes in rainbow trout (Oncorhynchus mykiss) juveniles fed extruded diets with varying levels of lupin (Lupinus albus), peas (Pisum sativum) and rapeseed (Brassica napus)

Varying levels of lupin (Lupinus albus), peas (Pisum sativum) and rapeseed (Brassica napus) meals were evaluated as partial replacements for fishmeal in extruded diets for rainbow trout, with particular emphasis on the effect on growth performance and the expression of three genes associated with immune response. A series of 10 isonitrogenous (450 g kg^?1 crude protein) and isolipidic (17 g kg^?1 crude lipid) diets were formulated to contain different levels of lupin (150 g kg^?1, 250 g kg^?1 and 350 g kg^?1), rapeseed cake (100 g kg^?1, 200 g kg^?1 and 300 g kg^?1) and pea (50 g kg^?1, 150 g kg^?1 and 250 g kg^?1) meals. The control diet was prepared with fish meal as the sole source of protein. Triplicate groups of fish (37.08 ± 3.58 g) were assigned to each experimental diet. The feeding experiment was conducted for 9 weeks at 14.3 ± 0.4 °C. The fish were hand fed three times per day, 6 days per week to apparent satiation level. Growth performance, feed utilization and immunological response were significantly affected by the type of plant protein as well as level of inclusion. Hepatosomatic index (HSI) increased in all groups of fish fed diets with pea and rapeseed cake meal. Dietary inclusion of lupin did not affect the expression of Mx‐1 gene. Our results suggest that fish meal can be replaced by lupin in the diet of rainbow trout without any apparent adverse effects on key innate immunological genes.