Bioprocessed Soybean Meal Research Articles

260 Identification of Candidate Gut Bacterial Species from Atlantic Salmon (Salmo salar) That Can Metabolize Ingredients Derived from Bioprocessed Soybean Meal

Abstract In the aquaculture industry, plant-based protein sources have emerged as an economically and environmentally sustainable replacement for traditional animal protein sources. Yet, due to decreased digestibility, the presence of anti-nutritional factors, and an increased risk of inflammation of the digestive system, the inclusions of plant-based protein ingredients must be limited in the diets of carnivorous fishes. To gain further insight on the adaptation of the fish digestive tract to plant-based protein ingredients, slurry from cultured Atlantic Salmon (Salmo salar) was used as a proxy in an in vitro model system to identify candidate gut bacterial species from fish that can metabolize bioprocessed soybean meal. Triplicate slurry cultures were supplemented with one of each of the following ingredients: fishmeal (FM – control#1), soybean meal (SBM-control#2), MEPro (bioprocessed soybean meal product), as well as three ingredients derived from bioprocessed soybean meal (SPC1 - soy protein isolate #1; SPC2 - soy protein isolate #2; SPC3 - soy protein isolate #3). Data were generated by Illumina MiSeq 2X300 sequencing of PCR-generated amplicons targeting the V1-V3 regions of the 16S rRNA gene. A comparative analysis of the most highly represented Operational Taxonomic Units (OTU) using the non-parametric Kruskal-Wallis sum-rank test and Wilcoxon pairwise test identified candidate bacterial species that were enriched in cultures supplemented with specific bioprocessed soybean meal-derived ingredients compared with non-supplemented cultures (negative control). These results indicate that certain species may utilize these ingredients. Notably, OTUs Ss_1-37437 and Ss_1-13316 were found in the greatest abundance in cultures supplemented with SPC1 (31.4 - 49.7%) and SPC2 (7.2 - 17.4%), respectively. Interestingly, both OTUs were likely to represent novel bacterial species, based on their limited nucleotide sequence identity to their corresponding valid relative: Ss_1-37437: Prevotella paludivivens (96.58%); Ss_1-13316: Acetoanaerobium sticklandii (86.51%). In contrast, the most abundant OTUs enriched in SBM- and MePro-supplemented cultures were likely strains of known bacterial species. Indeed, OTU Ss_1-00386 was most abundant in SBM-supplemented cultures (16.4 - 32.5%), and it was found to be closely related to Leuconostoc mesenteroides (98.69%), a bacterial species with reported probiotic properties, while OTU SS_1-10030, a close relative of Bacteroides graminisolvens (99.24%), was most highly represented in MePro-supplemented cultures (21.9 - 32.7%). Together, these results suggest that ingredients derived from bioprocessed soybean meal have the potential to be developed as prebiotics to modulate the gut microbiome of aquaculture fish species.

An initial evaluation of fishmeal replacement with soy protein sources on growth and immune responses of burbot (Lota lota maculosa)

Burbot (Lota lota maculosa) are the only freshwater member of the cod family (Gadidae) and potentially a new species for aquaculture production. This “freshwater cod” species could provide diversification for freshwater salmonid and other aquaculture operations, given its desirable fillet quality and growth potential. Burbot nutrition research is necessary to further define dietary requirements and the potential of this species to utilize sustainable plant-based proteins. A 91-day feeding trial and subsequent 28-day pathogen challenge was conducted with juvenile burbot (26.8 g mean weight) to assess growth performance, survival, and immune parameters. Dietary treatments included a fishmeal control (CTL), and 25% and 50% fishmeal replacement with soybean meal (SBM) soy protein concentrate (SPC), and bioprocessed soybean meal (BSBM). Growth results indicated a difference in percent gain (PG; P = 0.015) and thermal growth coefficient (TGC; P = 0.014) among dietary treatments, with the fish fed the SBM-25 and CTL performing higher than other diets except for the SPC-25. Analysis of distal intestine samples revealed no discernable differences in lamina propria thickness (P = 0.489) or cellularity (P = 0.944), and the amount of connective tissue of the submucosa was found to be similar (P = 0.988). Immediately following the feeding trial, burbot were challenged with a virulent strain of Aeromonas sp. (A141) while remaining on their respective dietary treatments. At day 28 post-challenge, no diet-related effects were found in cumulative percent mortality (P = 0.170) or serum lysozyme activity (P = 0.715). The respiratory burst activity of isolated head kidney-derived leukocytes did not show treatment differences at pre- and post-challenge sampling (P = 0.857), but activity decreased post-challenge (P < 0.001). Overall, results indicate that 25% FM replacements with SBM and SPC are suitable in burbot diets and long-term feeding of soy-based proteins does not appear to cause distal enteritis, impair disease resistance, or affect innate immune function. Utilizing soy-based protein sources for commercial burbot culture will expand the use of sustainable plant ingredients in aquaculture and provide burbot producers with a cost-effective alternative to high fishmeal feeds.

Effects of a Bioprocessed Soybean Meal Ingredient on the Intestinal Microbiota of Hybrid Striped Bass, Morone chrysops x M. saxatilis.

The hybrid striped bass (Morone chrysops x M. saxatilis) is a carnivorous species and a major product of US aquaculture. To reduce costs and improve resource sustainability, traditional ingredients used in fish diets are becoming more broadly replaced by plant-based products; however, plant meals can be problematic for carnivorous fish. Bioprocessing has improved nutritional quality and allowed higher inclusions in fish diets, but these could potentially affect other systems such as the gut microbiome. In this context, the effects of bioprocessed soybean meal on the intestinal bacterial composition in hybrid striped bass were investigated. Using high-throughput sequencing of amplicons targeting the V1–V3 region of the 16S rRNA gene, no significant difference in bacterial composition was observed between fish fed a control diet, and fish fed a diet with the base bioprocessed soybean meal. The prominent Operational Taxonomic Unit (OTU) in these samples was predicted to be a novel species affiliated to Peptostreptococcaceae. In contrast, the intestinal bacterial communities of fish fed bioprocessed soybean meal that had been further modified after fermentation exhibited lower alpha diversity (p < 0.05), as well as distinct and more varied composition patterns, with OTUs predicted to be strains of Lactococcus lactis, Plesiomonas shigelloides, or Ralstonia pickettii being the most dominant. Together, these results suggest that compounds in bioprocessed soybean meal can affect intestinal bacterial communities in hybrid striped bass.

Effects of Exercise and Bioprocessed Soybean Meal Diets during Rainbow Trout Rearing

Background:Alternative protein sources to fishmeal in fish feeds are needed.Objectives:Evaluate rearing performance of adult rainbow trout (Oncorhynchus mykiss) (initial weight 139.0 ±1.5 g, length 232.9 ± 0.8 mm, mean ± SE) fed one of the two isonitrogenous and isocaloric diets (46% protein, 16% lipid) and reared at one of the two levels of exercise (water velocities of either 3.6 cm/s or 33.2 cm/s).Methods:Protein in the control diet was based on fishmeal. In the experimental diet, bioprocessed soybean meal replaced approximately 60% of the fishmeal. Fish were fed by hand once-per-day to near satiation, and the food was increased daily. The experiment lasted 90-days.Results:There were no significant differences in gain, percent gain, or specific growth rate between the dietary treatments. However, the amount of food fed and feed conversion ratio was significantly lower in the 60% bioprocessed soybean meal diet. Intestinal morphology, relative fin length, splenosomatic index, hepatosomatic index, and viscerosomatic index were not significantly different in the trout fed either diet. Fish reared at 3.6 cm/s had a significantly lower feed conversion ratio (1.02 ± 0.02) than fish reared at 33.2 cm/s (1.13 ± 0.02). However, there were no significant differences in gain, percent gain, specific growth rate, or percentage mortality in fish reared with or without exercise. No significant interactions were observed between diet and exercise (higher water velocity).Conclusion:Based on these results, at least 60% of the fishmeal in adult rainbow trout diets can be replaced by bioprocessed soybean meal, even if higher water velocities are used to exercise the fish.

Bioprocessed soybean meal replacement of fish meal in rainbow trout (Oncorhynchus mykiss) diets

This 125-day experiment evaluated the growth of adult rainbow trout (Oncorhynchus mykiss) fed one of three isonitrogenous and isocaloric diets (46% protein, 16% lipid). Fish meal was the primary pr...

Direct Substitution of Fishmeal with Bioprocessed Soybean Meal in Brown Trout Diets

Direct Substitution of Fishmeal with Bioprocessed Soybean Meal in Brown Trout Diets

Dietary Bioprocessed Soybean Meal Does Not Affect the Growth of Exercised Juvenile Rainbow Trout (Oncorhynchus mykiss)

Context: This 88-day experiment evaluated the rearing performance of juvenile rainbow trout (Oncorhynchus mykiss) fed one of three isonitrogenous and isocaloric diets and reared at velocities of either 2.3 or 18.7 cm s-1. Objective: Evaluate the effects of diet and exercise during rainbow trout rearing. Design: Fishmeal was the primary protein source for one diet, with bioprocessed soybean meal (BSM) replacing either 60 or 85% of the fishmeal in the other two diets. Setting: This study was performed at Cleghorn Springs State Fish Hatchery in Rapid City, South Dakota, USA. Results: At the end of the experiment there were no significant differences among the dietary treatments in gain, percent gain, specific growth rate (SGR), or percent mortality. However, fish fed the fishmeal-based diet ate significantly more, experienced a significantly higher feed conversion ratio (FCR), and had a significantly higher hepatosomatic index than the fish fed the 85% BSM diet. Intestinal histology was not affected by the inclusion of BSM. Fish reared at 2.3 cm/s-1 had significantly lower FCRs, gain, percent gain, and SGR than the fish reared at 18.7 cm/ s-1. There was a significant interaction in food consumed between diet and velocity, but no other significant interactions between the dietary and exercise treatments were observed. Conclusion: Based on these results, BSM can replace at least 85% of the fishmeal in juvenile rainbow trout, even if the fish are exercised.

Rearing Performance of Juvenile Brown Trout (&amp;lt;i&amp;gt;Salmo trutta&amp;lt;/i&amp;gt;) Subjected to Exercise and Dietary Bioprocessed Soybean Meal

This 121-day experiment evaluated the rearing performance of brown trout Salmo trutta fed one of two isonitrogenous and isocaloric diets and reared at velocities of either 2.8 or 16.1 cm/s. Fishmeal was the primary protein source for the reference diet, and bioprocessed soybean meal replaced approximately 67% of the fishmeal in the experimental diet. At the end of the experiment, there were no significant differences in gain, percent gain, feed conversion rates, or specific growth rates between the dietary treatments. There were also no significant differences in intestinal morphology, splenosomatic, hepatosomatic, and viscerosomatic indices related to diet composition. However, gain, percent gain, feed fed, and specific growth rate were all significantly greater in brown trout reared at the higher velocity. No significant differences in any of the other variables measured were observed between the velocity treatments. There were no significant interactions between diet and velocity in any of the variables. Based on the results of this study, bioprocessed soybean meal can replace at least 67% of the fishmeal in brown trout diets, regardless of the rearing velocities used in this study. However, higher rearing velocities are recommended to maximize juvenile brown trout growth rates.

Evaluation of a bioprocessed soybean meal on nursery pig performance and immune status.

A total of 239 pigs (initial BW 6.56 ± 0.87 kg, 21 d of age) were used in a 35-d study to investigate the effects of fish meal (FM) and spray dried plasma (SDP) in combination with a bioprocessed soybean meal (SBM) on growth performance and immune responses in weaned pigs. Equal numbers of barrows and gilts were randomly allotted to 1 of 4 dietary treatments (10 pens/treatment) according to initial BW and sex: positive control (CON; corn/SBM diet) containing SDP and FM, the CON with bioprocessed SBM replacing FM (BPSBM), the CON with bioprocessed SBM replacing SDP (BPSBM), and the CON with bioprocessed SBM replacing both SDP and FM (BPSBM). Experimental diets were fed in Phase I (d 1-7 post-wean) and II (d 8-21) followed by a common Phase III diet (d 22-35); changes in BW and feed disappearance were determined accordingly. Pigs were sensitized against ovalbumin (OVA) and Candida albicans (CAA) on d 7 and 21. Assessment of immune response was based on lymphocyte proliferation in response to mitogens Concanavalin A and phytohemagglutinin (d 14 post-wean), dermal hypersensitivity to OVA and CAA (% increase in local swelling at 2, 6, 24, and 48 h post-injection) on d 28, and primary and secondary anti-OVA IgG at d 21 and 28, respectively. Pigs fed CON were heavier (P < 0.01) than pigs fed BPSBM and BPSBM, and not different from pigs fed BPSBM, at the end of Phase I and II (6.99, 6.80, 6.52, or 6.60 kg, pooled SEM 0.08, respectively in Phase I or 12.47, 12.18, 11.42, and 11.85 kg, pooled SEM 0.21, in Phase II, respectively). Hypersensitivity to OVA peaked at 2h in pigs fed CON, BPSBM, and BPSBM or peaked at 6h in pigs fed BPSBM (121.4, 165.6, 139.0, and 144.1%, pooled SEM 22.9, respectively, at 2 h and 86.7, 114.5, 95.0, and 156.8%, pooled SEM 29.4, respectively at 6 h). Peak response to CAA occurred at 2h in all groups (42.6, 55.2, 48.2, and 50.6%, pooled SEM 11.9, respectively, in the CON, BPSBM, BPSBM, and BPSBM, respectively). There was no difference in hypersensitivity due to experimental diet at any time point. Secondary anti-OVA IgG was 2-fold lower based on optical density values in pigs fed CON compared with BPSBM and BPSBM (0.78 vs. 1.56 and 1.55 optical density at 405 nm, pooled SEM 0.42, respectively). Dietary treatment did not impact lymphocyte proliferation. The bioprocessed SBM is a suitable alternative for FM and/or SDP in Phase I and II nursery diets based on pig growth. The prolonged hypersensitivity to OVA indicate that bioprocessed SBM may have a positive impact on pig immune function and the 2-fold increase in anti-OVA IgG warrants further investigation on the impact of bioprocessed SBM on pig immune function.

Gut histology, immunology and the intestinal microbiota of rainbow trout, Oncorhynchus mykiss (Walbaum), fed process variants of soybean meal

Processed soybean meal ingredients have become an emerging plant-based protein used in aquafeed formulations and have been shown to influence gastrointestinal health and microbiota in cultured species. Two 60-day feeding trials with juvenile rainbow trout (Oncorhynchus mykiss, Walbaum) were conducted to compare the effects of fishmeal (FMC), defatted soybean meal (SBM), bioprocessed soybean meal (BSBM) and commercial soy protein concentrate (CSPC) ingredients on intestinal histology, innate immunity and microbiota profiles. Results indicated no significant differences in intestinal immunoglobulin concentrations (p = .41) or gut leukocyte phagocytosis at day 15 samplings (p = .41). Intestinal lysozyme content was found to be highest at day 60 in the BSBM treatment group (p < .01). No significant differences across treatments were observed in histological profiles at day 0 (p = .75), day 15 (p = .08) and day 60 (p = .22). ANOSIM analysis for microbiota beta diversity showed differences among all treatment groups, with the exception of the high and low levels of BSBM (p = .40). There were also differences observed in the alpha diversity ratios, with significant differences in gut communities among dietary groups as demonstrated by Chao-1 (p < .01) and Shannon indices (p = .02). The incorporation of processed soy-based proteins alters the microbial community composition within the distal intestine, and modulates lysozyme concentrations within the distal intestinal tissues.

296 Evaluation of a bioprocessed soybean meal on nursery pig performance and immune status

296 Evaluation of a bioprocessed soybean meal on nursery pig performance and immune status

Growth performance, feed utilization and non-specific immune response of gilthead sea bream (Sparus aurata L.) fed graded levels of a bioprocessed soybean meal

The objective of this study was to evaluate the effects of partial fish meal replacement by a bioprocessed soy product (BS) in juvenile gilthead sea bream over the course of a 3-month trial. A diet with fish meal as the sole protein source (FM) was compared to diets with 20% (BS20), 40% (BS40) and 60% (BS60) of replacement. The effects of diets on growth performance, feed utilization, gut integrity, liver structure and immune status were evaluated. Weight gain, feed efficiency, daily growth index and specific growth rate decreased at the highest level of BS, while feed intake increased. In fish from BS40 and BS60 groups, indices indicating growth in response to protein intake such as protein efficiency ratio and protein productive value were decreased significantly. Body composition did not differ among groups for all parameters analysed. As far as non-specific immune response is concerned, spontaneous respiratory burst activity of blood significantly decreased at BS20 and BS40 groups, while stimulated activity did not indicate any significant change. Serum myeloperoxidase levels and total bacteriolytic activity of complement increased significantly at the highest dietary inclusion of BS, compared to the control group, while serum lysozyme levels did not indicate significant changes. Liver structure was not affected at any level, but some alterations in intestinal morphology were observed in the distal intestine mainly in the BS60 group. Overall, FM replacement by BS affected negatively gilthead sea bream growth performance at the 60% level, protein efficiency from the 40% level and affected some indicators of the immune response.

Total replacement of fish meal with plant proteins in diets for Atlantic cod (Gadus morhua L.) II — Health aspects

Replicate groups of Atlantic cod were fed 5 diets in which fish meal protein was replaced with 25% (25 PP), 50% (50 PP), 75% (75 PP) and 100% (100 PP) of a plant protein mixture containing 50% wheat gluten, 36% soy protein concentrate and 14% bioprocessed soybean meal. After 28 weeks, fish were sacrificed and analysed for growth, feed conversion, nutrient digestibility (see [Hansen, A.-C., Rosenlund, G., Karlsen, Ø., Koppe, W., Hemre, G.-I., Accepted for publication. Total replacement of fish meal with plant proteins in diets for Atlantic cod (Gadus morhua L.) I: Effects on growth and protein retention. Aquaculture]) and health status. Except for small reductions in the mean cell volume and haemoglobin content of red blood corpuscles, health indicators in blood and plasma were mostly unaffected by diet. Although the apparent digestibility coefficient (ADC) of nutrients was only marginally affected by diet [Hansen, A.-C., Rosenlund, G., Karlsen, Ø., Koppe, W., Hemre, G.-I., Accepted for publication. Total replacement of fish meal with plant proteins in diets for Atlantic cod (Gadus morhua L.) I: Effects on growth and protein retention. Aquaculture], faeces moisture content increased non-linearly peaking in fish fed the 100 PP diet where dry matter was only 11% compared to 18% in the control fish. This indicates a progression towards a diarrhoea-like condition in 100 PP fish. Feeding plant proteins did not affect gut relative weight but did affect intestinal morphology. In particular, there was a general increase in cellularity of the lamina propria and a modest goblet cell hypertrophy and hyperplasia which peaked in fish fed the 100 PP diet. More severe enteritis-like conditions were rare and found in only two fish fed the 100 PP diet. The dietary effect on goblet cells may be caused by phytate or fibres rather than the primary enteritis-inducing compounds found in untreated soybean meal. Hindgut segments seemed to be more affected than midgut thus suggesting an up-concentration of the causative agents of intestinal alteration in hindgut regions. Soyasaponins were not degraded during gut transit although the various conjugates were hydrolysed increasing the level of un-conjugated soyasaponins in the faeces. The intestinal level of heat shock protein 70 (HSP70) was unaffected by diet except in one replicate pen of fish fed the 100 PP diet where expression increased fourfold compared to the other replicate and other diets. The reason for this remains obscure. In conclusion, the plant ingredients used in the present study appear not to affect cod health to any major degree when used to replace up to 75% of fish meal protein. An increase to 100% may induce enteritis-like conditions in the guts of some fish and also activate HSP70 stress-gene mRNA expression in the intestine.

Characterisation of the microbiota associated with intestine of Atlantic cod ( Gadus morhua L.) : The effect of fish meal, standard soybean meal and a bioprocessed soybean meal

Populations of aerobic heterotrophic bacteria present in the gastrointestinal (GI) tract of healthy Atlantic cod ( Gadus morhua L.) fed three different diets, fish meal, standard or a bioprocessed soybean meal (BPSBM), were estimated using the dilution plate technique. A total of 944 isolates were characterised by biochemical and physiological properties and 425 isolates were identified further by sequencing the 16S rRNA genes. Our results showed that gut microbiota were affected by dietary manipulation. The GI tract of fish fed fish meal was dominated by Gram-positive bacteria of the genera Brochothrix and Carnobacterium. The Gram-negative bacteria Chryseobacterium spp. and Psychrobacter glacincola, and Gram-positive bacteria belonging to Carnobacterium, dominated in the digestive tract of fish fed soybean meal. In contrast to these results, genus Psychrobacter dominated in the GI tract when fish were fed BPSBM. Until recently, it was generally suggested that the gut microbiota of fish were less diverse than in homoeothermic animals. However, the present study identified several “new” bacterial species isolated from the alimentary tract of Atlantic cod. These “new” bacterial species are not normally isolated from the GI tract of fish. Based on our finding we suggest that the GI tract microbiota of fish might not be as simple as believed. Antagonistic activity of carnobacteria regarding inhibition of growth of two fish pathogens ( Aeromonas salmonicida ssp. salmonicida and Vibrio anguillarum) was observed. However, some difference in the antibacterial activity of Carnobacterium spp. was observed. Whether this antagonistic activity has any effect in challenge studies will be discussed, especially in relation to the finding that the digestive tract is one of the major infection routes in fish.

Digestive capacity, intestinal morphology, and microflora of 1-year and 2-year old Atlantic cod ( Gadus morhua) fed standard or bioprocessed soybean meal

The objectives of this work were to evaluate how dietary soybean meal (SBM) or a soy meal made by bioprocessing the SBM (BPSBM) to remove anti-nutritional factors affected hydrolytic capacity, amino acid absorption, intestinal morphology, and microflora along the intestinal tract of Atlantic cod at two life stages. Three fish meal based standard cod diets were formulated to contain no soy (FM control), 25% SBM, or 22% BPSBM. Prior to sampling the diets were fed to duplicate groups of 0.5 kg (1-year old) and 1.7 kg (2-year old) cod for a period of 3 months, and the groups reached 0.9 and 2.5 kg, respectively. Digesta was then sampled from different intestinal sections for analyses of trypsin and amylase activity as well as absorption of amino acids, nitrogen, and sulphur. Gastrointestinal sections were sampled for measurements of relative weight (kg − 1 body weight), and tissues from these sections were sampled for analyses of brush border enzyme (alkaline phosphatase (ALP), leucine aminopeptidase (LAP), and maltase) activity and histological examination. Microflora was sampled from both digesta and the intestinal wall. The SBM diet stimulated relative growth of all gastrointestinal sections except the distal intestine in both age classes. Relative growth of the pyloric intestine was also stimulated by BPSBM. The pyloric caeca and the upper mid intestine were found to be the major sites for enzymatic hydrolysis of protein and starch and for amino acid absorption. Dietary SBM and BPSBM did not alter the activity of trypsin and LAP, but the activity of these enzymes in the proximal intestine was affected by age, being higher in 1-year old than in 2-year old cod. The rate of amino acid, nitrogen, and sulphur absorption along the gastrointestinal tract was not affected by SBM, but was slowed by BPSBM. Dietary SBM or BPSBM did not alter the morphology of the intestinal mucosa in any sections of the cod intestine. The distal-most structure of the intestine, a compartment with inlet and outlet (anus) valves, showed very high microbial colonisation in the mucosal brush border. Inclusion of SBM in the diet changed the intestinal microflora, increasing the population level of transient bacteria in the pyloric and mid intestine, but reducing the population level of adherent bacteria throughout the intestine. To conclude, Atlantic cod appeared to have a robust and flexible digestive system able to adjust to high dietary levels of soy protein meals.

Digestibility of diets containing different soybean meals in Atlantic cod ( Gadus morhua); comparison of collection methods and mapping of digestibility in different sections of the gastrointestinal tract

The purpose of the experiment was to evaluate effects of partial replacement of fish meal with soybean meal on digestibility in Atlantic cod and effects of biotechnological processing of soybean meal. Other objectives were to find out if apparent digestibility in cod was affected by age, temperature and/or faecal sampling methods, and to map digestion and absorption patterns along the intestinal tract for different age classes and diets. A control diet with fish meal as the main protein source (FM), a diet with 24% of crude protein from conventional extracted soybean meal (SBM), and a diet with 24% of crude protein from a bioprocessed soybean meal (BP-SBM) were used. Yttrium oxide was added as an inert marker for digestibility determination. The diets were fed to duplicate groups of 534 g (1-year-old) and 1750 g (2-year-old) cod in seawater. Faeces were stripped from the distal-most section (distal chamber) of the intestine after 48 and 84 days of feeding. In addition, intestinal contents were removed by dissection after 84 days. The dissected intestine was divided into 5 sections and contents were analysed separately. Dietary soy did not alter the viscosity of the digesta. The replacement of fish meal protein with soybean protein reduced the apparent digestibility of crude protein, fat, energy and almost all amino acids, independent of type of soybean meal processing. Larger fish had higher digestibility of starch, ash and several amino acids than smaller fish. A temperature decrease from 9.1 °C at feeding day 48 to 6.8 °C at day 84 resulted in lower digestibility of starch, ash and several amino acids. Absorption of amino acids was quantitatively terminated in the distal part of the mid intestine when feeding the soy-containing diets, but continued into the distal chamber when feeding the FM diet. Absorption of fat was completed in the proximal part of the mid intestine when feeding the soy-containing diets, but continued into the middle part of the mid intestine when feeding the FM diet. Soy did not affect absorption pattern of starch along the intestinal tract. Faecal sampling by dissection resulted in higher apparent digestibility of macronutrients than stripping in the 2-year-old cod, and higher apparent digestibility of protein in the 1-year olds.

Feed intake, growth, and utilisation of macronutrients and amino acids by 1- and 2-year old Atlantic cod ( Gadus morhua) fed standard or bioprocessed soybean meal

This experiment evaluated the nutritional value of extracted soybean meal (SBM) for on-grown Atlantic cod, and if this was improved by bioprocessing into a product with reduced contents of antinutrients (BPSBM). Three iso-nitrogenous and iso-energetic extruded diets contained no soy (FM control), or 24% of total protein from either soy product. Each diet was fed to duplicate groups of 534 g (1-year old) and 1750 g (2-year old) cod in sea pens equipped with feed waste collectors. The experiment lasted 84 feeding days, the fish were weighed at days 48 and 84, and fish were sampled at days 0 and 87 to budget protein and energy utilisation by comparative slaughter. At day 48 faeces was collected for estimation of macronutrient, energy, and amino acid digestibility. The 1-year old cod reached weights ranging from 916 to 984 g, while the 2-year olds reached weights ranging from 2490 to 2644 g. There was no effect of age-class on growth rate estimated as TGC, but relative feed intake (% of BW) and FER were higher in the 1-year olds. Digestibility and retention of macronutrients were not affected by size. Still, the digestibility of most amino acids and the retention of several digested amino acids were highest in the 2-year olds. The body lipid content was similar in all groups, and did not change. There was no effect of diet on weight gain within age-classes, nor any general effect of diet on growth rate estimated as TGC. The digestibility of amino acids and the lipid was reduced when feeding the SBM and BPSBM diets, but cod of both age-classes compensated for this by increased feed intake and gastrointestinal growth, resulting in lower FER and reduced protein retention. Similar growth and body composition when feeding all diets and similar macronutrient and protein utilisation when feeding SBM and BPSBM showed that Atlantic cod have relatively high tolerance for dietary SBM.