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Replacement of fishmeal in feeds is critical for sustainable aquaculture growth. However, replacement with plant protein concentrates reduces fish performance. A rainbow trout strain selected for high performance on a plant protein diet was compared to a non-selected strain to identify physiological mechanisms associated with improved performance. Nutrient digestibility in fishmeal and plant protein diets was assessed and no strain differences were found. Levels of amino acids in the hepatic portal vein and caudal vein were measured at intervals after a single force-feeding of fishmeal, four plant protein concentrates, and a mixture of the concentrates with or without supplementation of three limiting amino acids. Each ingredient affected plasma amino acid levels in a singular manner when fed individually but without predictable additive effects when fed as a mixture. Amino acid supplementation altered uptake and plasma concentrations of all the essential amino acids. The selected trout strain fed the plant protein mixture with amino acids showed a synchronous and homogenous pattern for essential amino acids over time in the hepatic portal vein in contrast to that of the non-selected strain. The results demonstrate that selection favorably altered temporal dynamics of plant protein digestion.

In the previous edition, this chapter was part of the diet formulation and manufacture chapter. In this edition, a separate chapter is devoted to the topic. There are two reasons for this change. First, alternative ingredients increasingly used in fish feeds are less familiar, so identifying appropriate chemical tests to assess quality of alternative ingredients is needed. Second, as fishmeal levels in feeds are being reduced, fish feeds must be formulated to more precisely meet nutritional needs of fish, i.e., precision formulation. This makes it crucial to have tools to assess quality of feeds and ensure that available levels of essential nutrients are provided. The first portion of the chapter explains which chemical tests are appropriate to use to measure ingredient quality. Different ingredients present different potential quality problems. Interpretation of the results of chemical testing allows feed producers to select high-quality ingredients. In addition to chemical tests, microscopic examination of feed ingredients, somewhat of a lost art, is a valuable tool to detect adulteration of ingredients or heat damage. In the second portion of the chapter, in vivo methods of diet evaluation are presented. This includes digestibility measurements and calculations, feeding trials and their evaluation, and approaches to assess effects of diet on fish quality and safety to consumers. Finally, approaches used for economic evaluation of feeds are discussed.

The selection of the proper feed in combination with application of appropriate feed management strategies is the critical aspect of efficient aquaculture production. Matching feeding practices that account for nutrient density and physical characteristics of feed to provide the optimum daily supply of nutrients to optimize growth and health of the culture species is one of the most difficult aspects of aquaculture production to manage. There is no single set of feed management practices that cover the large number of farmed fish species, fish farming systems, and feed types. This chapter presents general feed management principles that will provide a basic knowledge base to use as a foundation for developing and applying science-based aquaculture feed management practices.

Fish farming based on natural food production in ponds has been practiced for millennia. Such systems are categorized as extensive aquaculture, the aquatic equivalent of grazing in livestock production. Food production could be enhanced by fertilizing ponds, but the practice of supplying feed to be consumed directly by fish was not developed until the adoption of semiintensive and intensive production. The capacity to formulate fish feeds to meet the essential nutrient requirements arose from discoveries in human and animal nutrition. In 1910, scientists discovered that foods contain factors that are essential for life. It is now known that 12 vitamins and 10 amino acids are essential in feeds for fish and other vertebrates. Fish nutrition research lagged behind animal nutrition research until the development of suitable semipurified research diets to which individual nutrients could be supplemented or deleted. This development accelerated fish nutrition research, leading to estimates of the quantitative dietary requirements of most essential nutrients for farmed fish, summarized in the 1973 National Research Council's bulletin, “Nutrient requirement of trout, salmon and catfish.” Aquaculture production and fish feed production have grown rapidly in the past three decades and required changes in feed formulations to reduce dependency on ingredients derived from marine resources. The focus of fish nutrition research is now on developing the knowledge needed for precision feed formulation through more precise estimates of nutritional requirements and use of alternate feed ingredients, especially for marine species. New technologies, specifically high-throughput “omics,” are being applied to fish nutrition research with the potential to advance understanding at the genetic, cellular, and organism levels. The role of fish nutrition in promoting fish health and reducing the environmental effects of aquaculture production will continue to be important research areas.

The sustainability of aquaculture has been debated intensely since 2000, when a review on the net contribution of aquaculture to world fish supplies was published in Nature. This paper reviews the developments in global aquaculture from 1997 to 2017, incorporating all industry sub-sectors and highlighting the integration of aquaculture in the global food system. Inland aquaculture—especially in Asia—has contributed the most to global production volumes and food security. Major gains have also occurred in aquaculture feed efficiency and fish nutrition, lowering the fish-in–fish-out ratio for all fed species, although the dependence on marine ingredients persists and reliance on terrestrial ingredients has increased. The culture of both molluscs and seaweed is increasingly recognized for its ecosystem services; however, the quantification, valuation, and market development of these services remain rare. The potential for molluscs and seaweed to support global nutritional security is underexploited. Management of pathogens, parasites, and pests remains a sustainability challenge industry-wide, and the effects of climate change on aquaculture remain uncertain and difficult to validate. Pressure on the aquaculture industry to embrace comprehensive sustainability measures during this 20-year period have improved the governance, technology, siting, and management in many cases. The volume of global aquaculture production has tripled since 2000 with positive trends in environmental performance, but the sector faces mounting challenges including pathogen management, pollution, climate change, and increasing dependence on land-based resource systems.

Alternative sources of fish oil (FO) are one of the major problems in aquaculture; therefore, the goal of the present study was to examine insect (black soldier fly larvae) oil (BSLO) as a potential replacer of fish/soy oil in juvenile rainbow trout (initial average weight of 32 ± 0.15 g) feed. Four diets were formulated wherein FO (control diet) was completely replaced with either soybean oil (SO) or BSLO, and an additional BSLO-based diet supplemented with 1.5% bile acid (BSLO + BA) were fed to the fish for 10 weeks. Growth performance of the BSLO fed group was similar (P > 0.05) to that of the FO and SO fed groups, however, the fish fed BSLO + BA diet registered the lowest growth (P 0.05) affect the major nutrient content of whole-body, however, the fatty acid composition of the muscle and liver was influenced (P

The sustainability of aquaculture has been debated intensely since 2000, when a review on the net contribution of aquaculture to world fish supplies was published in Nature. This paper reviews the developments in global aquaculture from 1997 to 2017, incorporating all industry sub-sectors and highlighting the integration of aquaculture in the global food system. Inland aquaculture-especially in Asia-has contributed the most to global production volumes and food security. Major gains have also occurred in aquaculture feed efficiency and fish nutrition, lowering the fish-in-fish-out ratio for all fed species, although the dependence on marine ingredients persists and reliance on terrestrial ingredients has increased. The culture of both molluscs and seaweed is increasingly recognized for its ecosystem services; however, the quantification, valuation, and market development of these services remain rare. The potential for molluscs and seaweed to support global nutritional security is underexploited. Management of pathogens, parasites, and pests remains a sustainability challenge industry-wide, and the effects of climate change on aquaculture remain uncertain and difficult to validate. Pressure on the aquaculture industry to embrace comprehensive sustainability measures during this 20-year period have improved the governance, technology, siting, and management in many cases.

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

Replacement of fishmeal as the major protein source in feeds is critical for continued growth and sustainability of the aquaculture industry. However, numerous studies have shown suboptimal fish growth performance and reduced protein retention efficiency when carnivorous fish species are fed low fishmeal-high plant protein feeds. A study was conducted using a commercial strain and a genetically improved strain of rainbow trout selected for improved performance when fed an all plant protein diet to identify physiological differences associated with growth performance in the selected trout strain. Fifty individuals per strain (average weight ~ 580 g) were force-fed a plant-protein blend with and without amino acid supplementation (lysine, methionine and threonine) at 0.5% body weight and sampled at intervals over 24 h. Samples from intestine and liver were analyzed for specific gene expression analysis related to amino acid transporters, digestive process control, protein degradation and amino acid metabolism. The results showed that expression levels of various intestinal amino acid transporters (SLC1A1, SLC7A9, SLC15A, SLC1A5 SLC6A19 and SLC36A1) were affected by strain, diet and time. Moreover, significant interactions were found regarding the temporal expression levels of cholecystokinin (CCK-L), Kruppel-like factor 15 (KLF15) and aspartate aminotransferase (GOT) transcripts in the examined tissues. The results provide evidence that improved growth and protein retention of the selected strain fed an all-plant protein diet is a result of nutritional adaptation and an overall change in physiological homeostatic control.

In this Review, the Competing Interests section should read as follows: ‘R.L.N. is a member of the Forest Protection Advisory Panel at Cargill, and the Center on Food Security and the Environment (FSE) has received funding from the Cargill Foundation for visiting scholars and staff support, but not for research activities. She is also on the Scientific Advisory Board for Oceana and is the President of the Board of Directors for the Aspen Global Change Institute. She participates on the editorial board of Aquaculture Environment Interactions. D.H.K. is a member of the Technical Advisory Group for the Aquaculture Stewardship Council and a member of the Aquaculture Technical Advisory Committee of Monterey Bay Aquarium’s Seafood Watch Program. S.E.S. serves on the Advisory Committee on Aquaculture Science for DFO Canada (http://www. dfo-mpo.gc.ca/aquaculture/advisory-comm-consultatif-eng.html). She is currently working on two white papers for the United Nations Food and Agricultural Organization, and has previously chaired the Aquaculture Stewardship Council’s Technical Advisory Committee and the Monterey Bay Seafood Watch Advisory Committee. She also serves as Editor-in-Chief for the Journal of Shellfish Research, and Editor-in-Chief for Reviews in Fisheries Science & Aquaculture. A.H.B. is on the Standards Oversight Committee of the Global Aquaculture Alliance. He has no affiliation with any for-profit company; all of his research is supported by the Chilean National Science Agency (ANID) and therefore has no conflict of interest with any aquaculture activity. S.R.B. is a member of the Standards Oversight Committee of the Global Aquaculture Alliance, the Multi-Stakeholder Group of Monterey Bay Aquarium’s Seafood Watch programme, the Technical Advisory Committee of the Good Fish Foundation in the Netherlands, and the Technical Advisory Committee of the Aquaculture Program of the Sustainable Trade Initiative (IDH). He has received funding from the Monterey Bay Aquarium’s Seafood Watch programme for the development of Aquaculture Governance Indicators. R.W.H. is Editor-in-Chief of Aquaculture Research. In the past five years, he served as Chair of a Global Aquaculture Alliance committee that revised and updated best practices standards for fish feeds, a project that was completed in 2019, prior to his participation on this Review. In the past, also prior to this Review, he has been a principal investigator for grants and contracts awarded to the University of Idaho and received grants and contracts from industry or industry groups including the United Soybean Board, Enz-A-Bac, Midwest Ag Enterprises, Ajinomoto NA and Knipbio to assess feed ingredients for sustainable aquaculture. L.C. is a judge of the global F3 (fish-free feed) challenge. She was on the Scientific Advisory Board for the Aquaculture Stewardship Council between 2017 and 2019. She has no affiliations with for-profit companies. D.C.L. has received in-kind and financial support from a wide range of commercial and non-commercial entities, serves as a committee member for standards organizations and is a director of a commercial tilapia hatchery in Thailand. J.L. until recently served on the boards of The David and Lucile Packard Foundation, Oceano Azul Foundation, Prince Albert II of Monaco Foundation, the National Geographic Society, and Seafood Businesses for Ocean Stewardship (SeaBOS). She also co-chaired the Expert Group for the High Level Panel for a Sustainable Ocean Economy. She resigned from all of these roles in February 2021 when she took up her new position in the White House. M.T. is a member of the Program committee for The Marine and Coastal Science for Management (WIOMSA/MASMA), member of Action Areas and Solution Clusters Working Groups – Blue foods, United Nations Forum on Sustainability Standards (UNFSS), scientific lead for SeaBOS, and a Review Editor for Aquaculture Environment Interactions.’ The Review has been corrected online.

Federally endangered Rio Grande Silvery Minnows (RGSM; Hybognathus amarus) were raised in one of three culture regimes: intensively, with only a hatchery diet; semi-intensively with access to natural food and hatchery diet supplementation; and with only natural food available at the Los Lunas Silvery Minnow Refugium (Los Lunas, New Mexico), a naturalized conservation refugium designed to mimic the natural environment of the RGSM in the Rio Grande. The project compared each culture regime and assessed differences and similarities in lipid and fatty acid content between feeding an artificial diet and consumption of natural food items in this species. After 117 d, whole-body lipid levels and fatty acid profiles were measured in each group and compared with values for wild RGSM. Fish fed the hatchery diet exclusively or as supplementary feed had significantly higher percent lipid (15.5% ± 0.5% and 10.6% ± 0.1%, respectively) than fish raised without access to the diet. Both groups had significantly higher percent lipid than fish raised in the refugium or wild fish (8.3% ± 0.1% and 7.8% ± 0.2%, respectively). Condition factor differed among groups and was highest in fish fed the hatchery diet (1.00) followed by fish supplemented with the hatchery diet (0.93), refugium fish (0.91), and wild fish (0.90). In this respect, refugium fish appeared more similar to wild fish than fish fed the hatchery diet or offered the diet as a supplement. Comparison of fatty acid profiles among groups showed marked differences among wild fish, refugium fish, and those fed the hatchery diet, either exclusively or as supplementary feed. Total omega-3 fatty acids, expressed as percentage of total fatty acids, were highest in wild fish but similar among other groups. Total omega-6 fatty acids showed an opposite trend, with five to nine times higher percentages of linoleic acid observed among fish from the three culture regimes compared with wild fish. Significant differences in lipid content and fatty acid composition between wild RGSM and cultured silvery minnows reflected their respective diets and culture regimes. Given similarities in fat content and condition factor with wild RGSM, we conclude that fish in the refugium do not require supplemental feeding with an artificial diet for this type of naturalized conservation management. Results from this study show that RGSM readily forage on natural food items present and also artificial feed when available, indicating dietary plasticity, which is advantageous for fish culture and future recovery.

During the tuna canning process, about 52~54% of the total weight of the fish is discarded as waste, which can be processed in order to obtain tuna byproducts meal (TBM), or stabilized as tuna silage hydrolysates (TSH). Both products were tested as replacements of soybean meal (SBM), in diets for fingerling male Nile tilapia Oreochromis niloticus. Seven test diets were isonitrogenous (35% CP) and isoenergetic (19 kJ g-1): a basal diet contained SBM as main protein source (TSH0); four experimental diets had increasing inclusion levels of TSH replacing 25, 50, 75 and 100% of the SBM protein. The sixth diet contained TBM as sole protein source, and a commercial feed for tilapia was used as reference diet (RD). The diets were fed for eight weeks to triplicate tanks, each with 15 fry tilapia (initial weight of 0.89 ± 0.29 g). Tilapia fed the TBM diet had greater weight gain and feed intake, and lower feed conversion ratios than those fed diets containing with TSH. The RD, TSH25 and TSH50 diets gave the similar growth response. Fish fed diets TSH0, TSH75% and TSH100% showed reduced growth performance.

Background Falls in older adults precipitate hospitalisation, frailty and premature mortality and are a growing health concern. The standing balance test is a simple, cost effective tool used to screen for fall risk in adults aged 65+, however the association between standing balance and fall risk has not been examined in individuals younger than 65. To assess whether balance tests could be utilised to screen for fall risk at younger ages, we investigated if balance at ages 53 and 60–64 was associated with prevalence and frequency of subsequent falls. Methods Data from the MRC National Survey of Health and Development, a British birth cohort study, were utilised (n=2571). Standing balance time (eyes closed) was assessed at ages 53 and 60–64 (max: 30 seconds). Fall history within the last year was self-reported at ages 60–64 and 68 and categorised to indicate fall prevalence (yes, no) and frequency (0, 1–2, 3+). Binary and multinomial logistic regressions were used to assess associations of balance time (per 1 second increase) with fall prevalence and frequency, respectively. Adjustments were made for sex, height, BMI, socioeconomic position, physical activity, smoking, knee pain, diabetes, cardiovascular events and respiratory and depressive symptoms. Results Women reported higher prevalence of falls than men at ages 60–64 (23% vs 14%) and 68 (26% vs 18%). Longer balance time at age 53 was associated with reduced odds of falling at age 60–64 [OR: 0.98 (95% CI: 0.97,1.00)]; similar associations were found between balance at age 60–64 and falls at age 68 [0.96 (0.93,0.99)]. Better balance at age 53 was associated with lower risk of 3 or more falls (vs no falls) at ages 60–64 [RRR: 0.88 (0.80,0.98)] and 68 [0.93 (0.88,0.97)]. Better balance at age 60–64 was also associated with lower risk of 3+ falls at age 68 [RRR: 0.92 (0.85,0.98)] and in addition was associated with lower risk of 1–2 falls [0.97 (0.94,1.00)]. These associations remained after adjustments. Discussion Poorer balance at ages 53 and 60–64 was associated with subsequent fall risk. Balance at age 53 was most strongly associated with 3 or more falls, while balance at age 60–64 was associated with both 1–2 and 3+ falls. Whether this is due to stronger associations at age 60–64 or a shorter time between balance and falls assessments requires further investigation. Balance tests in middle age may help identify high risk individuals who would benefit from earlier interventions to prevent future recurrent falls.

A wide range of raw materials are now used routinely in aquaculture feeds throughout the world, primarily to supply protein and energy in the form of lipid from edible oils. Protein meals and oils used can generally be divided into those of plant or animal origin and many have considerable potential to supply the required dietary nutrients required by aquaculture species. However, the use of any raw material introduces a suite of risks that need to be considered to enable the production of safe, sustainable and functional feeds to underpin this sector. A lack of understanding of some of those risks can result in failure of dietary specifications being met and/or negative nutritional elements being introduced (e.g. antinutritional factors). Importantly, it is this feed that when fed to food‐producing animals is such an important element of food safety, and as such any undesirable aspects relating to feed production can also have a negative impact on the rest of the food chain. However, there is some disparity internationally among raw materials that are used and the perceptions surrounding the risk of their use. It is the scientific assessment of these risks that is the basis of this review.

Increasing feed efficiency and muscle growth in aquaculture are of high priority and require understanding how dietary components are interactively processed and trigger molecular, tissue and whole-body responses. A 67-day trial was conducted to describe the effects of three feeds with varying dietary protein (P) to lipid (L) ratios (43P:20L, 50P:15L, 62P:6L) on growth trajectory, body composition, nutrient deposition, muscle histology, gene expression and protein degradation pathways of juvenile rainbow trout (initial weight 11.2 g). The growth trajectories of trout fed the 43P:20L and 50P:15L diets were identical and higher than trout fed the 62P:6L diet. The overall TGC was 0.261 for trout fed the 43P:20L and 50P:15L diets. Feed intake was associated with dietary protein level, not energy. Body composition differed among treatments early (at day 14) in the experiment and continued throughout. Body lipid and body protein contents varied significantly (P Statement of relevance Nutrigenomics can foster sustainable aquaculture.

There is increasing interest in using plant-derived extracts to promote growth and health in finfish species in recent years. Elucidating the effects of plant secondary metabolites on skeletal muscle growth signaling will contribute to an improved understanding of the effects of feeding carnivorous fish diets supplemented with plant extracts on fish somatic growth. Dietary intake of anthocyanins, a type of flavonoid widely distributed in plants, has long been associated with beneficial effects in both human and animal health; however, their effects in finfish are largely unknown. We conducted an experiment to test the effect of three doses (treatments A, B and C; 1 ×, 2.5 × and 10 ×, respectively) of a mixture of three types of anthocyanidins (peonidin, cyanidin and pelargonidin chloride) on the expression of several genes in primary myogenic cells isolated from the skeletal muscle of rainbow trout ( Oncorhynchus mykiss ) after 24 h of treatment. The genes of interest analyzed are involved in myogenic programing ( pax7 , myoD and myogenin ), Notch signaling ( her6 and hey2) and antioxidant enzymes ( sod1 , cat and gpx1 ). Significantly greater expression of pax7 in cells under treatment B compared with the untreated cells was detected. Although no differences in expression of myogenic regulatory factors, myoD and myogenin between test groups or the control were detected, a trend toward significantly lower expression in all groups tested compared with the control group was observed. Moreover, significantly higher expression levels of her6 and hey2 in cells under treatments A and B compared with untreated cells were detected. Although no significant differences in the expression of cat and sod1 , significantly greater expression in gpx1 in all treated groups compared with the control group was detected. Collectively, we demonstrated that anthocyanidins enhance the expression of gpx1 in primary myogenic cells, thereby contributing to skeletal muscle tissue defense against oxidative stress in finfish species. Further, anthocyanidins appear to delay myogenic differentiation in primary myogenic cells by up-regulating the expression of pax7 while decreasing myogenic regulatory factors in a Notch signaling-dependent interaction. Whether this effect results a reduced growth performance and/or an increase in feed conversion ratio in fish fed diets supplemented with plant extracts rich in anthocyanins or anthocyanidins needs further study, and the need to better define the potential effects of different polyphenol classes in myogenic differentiation on primary myogenic cells from carnivorous fish is warranted. Statement of relevance The study contributes to increase our understanding regarding the effect of plant-derived secondary metabolites such as anthocyanidins on myogenic program and antioxidant enzyme defense in differentiating myogenic cells from carnivorous fish. We have demonstrated that anthocyanidins may delay the progress of the myogenic differentiation process and promote antioxidant defense expression in myogenic cells.

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, amino acids, and gross energy in various feed ingredients with or without protease supplementation (Jefo Nutrition Inc., Quebec, Canada) were determined for rainbow trout in a two-year study. The ingredients consisted of two feather meals, two poultry by-product meals, two meat and bone meals, sardine meal, menhaden meal, black soldier fly larvae meal, Methanococcus maripaludis single cell protein, soybean meal, canola meal, distiller's dried grains with solubles (DDGS), cottonseed meal, peanut meal, sunflower meal, and algae (Spirulina sp.) meal. A reference diet with 0.1% yttrium oxide as inert marker was mixed with test ingredients in a 70:30 ratio to produce a series of test diets. Fish were fed their respective diets and fecal samples were collected by stripping. ADC of dry matter for rainbow trout ranged 51.0–86.6% for animal products and single cell protein and 33.1–70.1% for plant products without protease supplementation. ADC (without protease supplementation) of protein and energy ranged from 55.4–84.5% and 58.1–90.2%, respectively, for animal products, and 70.0–83.8% and 32.9–76.0%, respectively, for plant products. Supplementation with the commercial protease (175 mg protease complex/kg of diet) resulted in ingredient-specific ADC increases for dry matter, energy, cysteine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tyrosine, alanine, aspartic acid and glutamic acid, with most ingredients having improved digestibility of at least one amino acid. Protease supplementation had the most profound improvement on ADCs for soybean meal, including dry matter and the majority of individual amino acids. Overall, this research demonstrates the benefit of protease supplementation on the digestibility of feed ingredients commonly used in rainbow trout and other commercially cultured fish feeds, although the degree of improvement in digestibility varied among ingredients. Further studies with this protease are recommended to evaluate its effects at higher inclusion levels and in other species of cultured fishes.

A 12-week feeding trial was conducted to compare low and high inclusions of conventional soybean meal (SBM) or enzyme-treated SBM (Enzo) as fishmeal replacements in the diets of rainbow trout, Oncorhynchus mykiss. Six isonitrogenous (43% crude protein) and isolipidic (19% crude lipid) diets were produced: a control diet (fishmeal-based) and five experimental diets replacing fishmeal by 8% or 16% with SBM (low or high SBM, respectively); 8% or 16% with Enzo (low or high Enzo, respectively); and 16% with SBM + Enzo blended with 50:50 ratio (Enzo + SBM). Triplicate tanks, each containing 40 fish, were hand-fed to apparent satiation. Compared with the control, all groups that consumed SBM or Enzo diets had lower growth performance (P 0.05). Whole-body content of some essential amino acids (e.g. isoleucine, leucine and valine) showed a significant corresponding decrease with high dietary SBM inclusions. Trypsin activity in the proximal intestine decreased significantly with increasing dietary SBM and Enzo levels. Hepatic expression of GHR1 was greater in high SBM and high Enzo + SBM treatments compared to the control diet, which exhibited the highest expression of IGF-II (P

A 12-week feeding trial was conducted to compare the dietary lysine requirement of a fast-growing strain (FGS) and a slow-growing strain (SGS) of rainbow trout, Oncorhynchus mykiss. Five isonitrogenous (37% digestible protein) and isocaloric (17.6 MJ/kg of digestible energy) diets were formulated and supplemented with l -lysine HCl (98.5% lysine) in increments of 0.40% (1.80, 2.20, 2.60, 3.00 and 3.40% diet) resulting in analyzed lysine values of 1.83 (Lys1.83), 2.20 (Lys2.20), 2.67 (Lys2.67), 3.06 (Lys3.06) and 3.52 (Lys3.52) g/100 g diet, respectively. Juvenile rainbow trout from the FGS (initial weight 12.2 ± 0.3 g) and the SGS (initial weight, 8.54 ± 0.19 g) were randomly stocked to 145-L tanks, each containing 35 fish per tank, in a 2 by 5 factorial design. Each diet was fed to three replicate tanks of each strain to apparent satiation three times daily. After 12 weeks of feeding, the FGS had significantly higher final weight and daily feed intake (g/fish) than the SGS. No significant diet by strain interactions were detected. Dietary lysine significantly improved body weight gain, and calculated indices of weight gain in both strains up to 2.20% dietary lysine, but not higher. However, whole body crude protein and crude lipid levels significantly increased and decreased, respectively, in both strains with increasing dietary lysine supplementation up to 2.7%–2.8% using broken line regression. The only significant difference between strains was found in protein retention, indicating differences in lean body weight gain. Using broken-line regression analysis of protein retention, the optimum dietary lysine level for the FGS and SGS were 2.75 (6.18) and 2.23 (5.01) % of diet (% of dietary protein), respectively. Lysine retention decreased with increasing dietary levels in both strains. Whole body essential amino acid content, with the exception of arginine, showed significant increases with dietary lysine levels in both strains of rainbow trout. Liver aspartate transaminase activity significantly increased with increasing dietary lysine in both strains, but alanine transaminase activity did not. The results suggest that the optimum dietary lysine requirement of rainbow trout for lean-body growth and protein retention differs with fish strain and is independent of feed intake.

A study was conducted to determine the benefits of the intake of purple corn extract (PCE), a natural source of anthocyanins, in rainbow trout, Oncorhynchus mykiss. A control or test diet supplemented with 5% PCE was fed to triplicate tanks with 25 fish each for 8 wk. The concentrations of three anthocyanins, cyanidin-3-glucoside, pelargonidin-3-glucoside, and peonidin-3-glucoside, were measured in PCE. The chemical composition and fatty acid profiles of fish, as well as the fatty acid profiles in plasma, liver, and muscle were determined. The total antioxidant capacity (TAC) and the concentration of oxidative damage biomarkers, for example, protein carbonyls, 8-hydroxydeoxyguanosine, and thiobarbituric acid reactive substances (TBARS), were determined in plasma. Transcription of two antioxidant enzymes, glutathione peroxidase 1 (gpx1) and superoxide dismutase 1 (sod1), was measured in erythrocytes. Significant lower adiposity and significant higher percentage of total n-3 and total n-6 polyunsaturated fatty acids (PUFA) in the body of fish fed the test diet were detected. Significant higher plasma percentage of total n-3 PUFA, significant higher plasma TAC, and significant higher expression of gpx1 in erythrocytes of fish fed the test diet were measured. Overall, our results suggest potential protection against in vivo lipid peroxidation in fish fed the PCE supplemented diet. This is especially true due to detection of an enhanced antioxidant protection in plasma and erythrocytes in fish, the reduced adiposity and greater proportion of total n-3 and n-6 PUFA in the fish body, as well as a tendency toward lower TBARS plasma concentration in fish fed the test diet when compared to the control group.

Salmonid ecology and conservation projects often necessitate distinguishing the offspring from anadromous or nonanadromous mothers, but the forms are often physically and genetically similar. We reared Oncorhynchus mykiss fry produced by anadromous mothers on one of two diets: one rich in and the other depleted in marine nutrients. We then sampled and analyzed fin and muscle tissues from fish fed both diets for nitrogen stable isotopes over time. Tissue nitrogen values from fish on the marine-nutrient-depleted diet indicated the size and time cutoffs at which offspring of anadromous O. mykiss no longer reflected a marine origin (muscle tissue cutoff: 0.81 g, 50.8 mm, and 29.4 d postfeeding; fin tissue cutoff: 0.65 g, 45.9 mm, and 35.3 d). Salmonids smaller than 50 mm cannot provide a sufficiently large fin sample for isotopic analysis without significant risk of mortality. Therefore, our experiment did not reveal a period when fish were large enough to provide a nonlethal fin clip but still mainta...

Apparent digestibility coefficients (ADCs) for dry matter, crude protein, energy and essential amino acids for five commonly used feed ingredients were determined for juvenile spotted rose snapper Lutjanus guttatus (average body weight 90.6 g). ADCs were determined using the stripping technique to collect faeces after fish were fed a reference diet and test diets composed of 700 g kg−1 reference diet and 300 g kg−1 test ingredient. Chromic oxide (Cr2O3) was used as an inert indicator. Ingredients tested included sardine fishmeal (FM), canola meal (CM), tuna by-products meal (TBM), poultry by-product meal pet grade (PBM-PG) and solvent-extracted soybean meal (SBM). In general, all ingredients showed high digestibility values for all essential amino acids, although differences were detected among ingredients. ADC values for dry matter, protein and energy ranged 77.0–80.4%, 84.3–82.5% and 89–88.8%, respectively, for marine ingredient and land-based animal protein sources, and 75.0–74.2%, 81.5–80.9% and 87.4–86.8%, respectively, for the plant-based protein source. SBM, TBM and PBM-PG should be further evaluated in feeding trials as partial FM replacements in rose snapper L. guttatus diets. Knowledge of ADC values for these ingredients will allow feed producers to develop nutritionally balanced, low-cost feed formulations for this species.

An 8-week feeding trial was conducted to determine the effectiveness of replacing fish meal (FM) with blends of alternative proteins in diets for white seabass (WSB, Atractoscion nobilis) at a starting weight of 5.6 g. Five diets were formulated with 400–440g kg−1 crude protein (380g kg−1 digestible). These included a high 520g kg−1 FM control diet, a series of three diets with a sequential replacement of FM containing 410g kg−1, 510g kg−1 and 630g kg−1 of a soy-based protein blend (SPC) and 200g kg−1, 100g kg−1 and 0g kg−1 FM, respectively and a fifth diet containing 550g kg−1 of a corn-based protein blend (CGM) and 100g kg−1 FM. Survival was highest in the FM control group at 99% but all other performance measures (weight gain, feed conversion ratio, specific growth rate and protein retention efficiency) were worse than the other treatment groups. Weight gain reached a maximum of 595% in the SPC 200g kg−1 FM treatment group. Performance decreased as inclusion of the soy-based protein blend increased. The CGM treatment performed comparably to the SPC 100g kg−1 FM treatment among all measures, except for survival, which was higher in the CGM 100g kg−1 FM treatment. With nutrient levels and alternative protein blends used in this study, FM can be reduced to 100g kg−1 of the diet for WSB without reductions in performance.

This study investigated the growth and immune function effects following partial replacement of fish meal with dried testes meal from pink salmon ( Oncorhynchus gorbuscha ) testes collected from Alaskan seafood processing byproducts. It was hypothesized that the dietary nucleotide content of testes meal may provide an immunostimulatory effect in rainbow trout ( Oncorhynchus mykiss ). Three diets were formulated and used for this study; a commercial type control diet, a Macrogard diet, and an experimental diet containing 50 g kg − 1 testes meal. Triplicate groups of juvenile rainbow trout (8.65 ± 0.13 g fish − 1 ) were fed each diet for 12 weeks, at which time they were challenged with Flavobacterium psychrophilum (the causative agent of coldwater disease). No significant differences in feed conversion ratio or specific growth rates were observed. Kidney macrophage (phagocytic) activity was significantly (P

A 12-week feeding trial was conducted to examine the replacement of fish meal with pet-grade poultry by-product meal (PBM-PG) in the spotted rose snapper Lutjanus guttatus diet. Five experimental diets were formulated to contain graded levels of PBM-PG at proportion of 250, 500, 75 or 900 g kg−1. The control diet contained sardine fish meal as the main protein source. Four groups of 15 randomly assigned L. guttatus juveniles were fed to satiation 3 times day−1. Except for the fish fed the PBM-PG90 diet, the growth performance, survival and feed utilization efficiency of the experimental fish were not significantly lower than those of the control fish. The dietary level of PBM-PG did significantly affect the haematological characteristics (P

This study evaluated the use of tuna by-product meal (TBM), a locally produced feed ingredient, as a replacement for fish meal (FM) in diets for spotted rose snapper, Lutjanus guttatus. Six isonitrogenous compounds [480 kg−1 crude protein (CP) and isoenergetic diets (21 kJ g−1)] were formulated to replace 0 (D-0%), 10 (D-10%), 20 (D-20%), 30 (D-30%), 40 (D-40% or 50% (D-50%) of FM protein with TBM protein. Each diet was fed to four replicate groups of spotted rose snapper (initial weight 5.4 g ± 0.04 g) to apparent satiation three times a day. After 8 weeks of feeding, the fish gained 4–5 times their initial weight. Spotted rose snapper fed D-30% had a significantly higher specific growth rate (2.7% day−1) than fish fed the other diets containing lower or higher amounts of TBM. Haematological parameters and whole-body proximate composition were unaffected by diet (P > 0.05). The ADC for protein and energy in D-0%, D-20% and D-30% were significantly higher than those for the D-40% and D-50% groups. A broken line model indicated that 262 g kg−1 TBM in the diet would yield maximum growth of the spotted rose snapper. The results of this study demonstrate that TBM is an acceptable ingredient for replacing 25–30% of dietary protein from FM in spotted rose snapper diets but that higher replacement levels reduce fish performance.

A study was conducted to evaluate the effects of lowering dietary fishmeal (FM) and crude protein (CP) levels, while maintaining essential amino acid levels, on growth performance, body composition, muscle metabolic gene expression, and chronic stress response of rainbow trout, Oncorhynchus mykiss, with and without handling stress. Eight experimental diets (isocaloric) with a 4 × 2 factorial design were formulated to contain two levels of FM (20%, 5%) and four levels of CP (48%, 45%, 42%, 39%). Diets were supplemented with increasing levels of amino acids to maintain dietary essential amino acid (EAA) levels. Trout (34.8 ± 0.3 g) were fed to apparent satiation twice daily for nine weeks to assess growth performance under laboratory rearing conditions, and then for an additional six weeks with and without exposure to handling stress (30 s of chasing followed by 30 s of netted air exposure) twice per week. The 9-week growth trial demonstrated that reducing dietary FM levels from 20% to 5% significantly reduced fish growth and increased feed conversion ratio (P .05) after 6-weeks of repeated handling stress. The expression of genes in the gcn2/eif2α/atf4 pathway, triggered in response to protein or amino acid starvation, were evaluated. General control nonderepressible 2 (gcn2) decreased with increasing dietary CP level above 42% (P

Fishery processing by-products are a large resource from which to produce fishmeal and other products for a variety of uses. In this study, testes meal (TM) produced from pink salmon processing by-product was evaluated as a functional ingredient in aquafeeds. Nile tilapia and rainbow trout fry were fed five isonitrogenous and isoenergetic experimental diets for 4 and 9 weeks respectively. Two diets were fishmeal-based (FM) and three were plant protein-based (PP). Salmon TM was added to the FM and PP diets at 7% to replace 20% of fishmeal protein (FMTM and PPTM respectively). An additional control diet was prepared in which fishmeal was added to the PP diet to supply an equivalent amount of protein as supplied by TM (PPFM). Inclusion of TM in both the FM- and PP-based diets resulted in higher final body weights, although differences were only significant between rainbow trout fed FM or FMTM diets. Similar differences were calculated for other indices of fish performance, e.g. specific growth rate, feed conversion ratio, protein efficiency ratio and protein retention efficiency. Feed intake was significantly higher for fish fed FMTM compared with FM in rainbow trout. For tilapia, final weights were numerically higher, but not significantly different for fish fed diets containing TM compared with non-TM diets (FM vs. FMTM; PP vs. PPTM). Performance of trout or tilapia fed the PPFM diet did not increase compared with the PP diet. The results indicate that TM addition to both FM and PP diets increased feed intake and also increased metabolic efficiency, demonstrating that TM can be a functional ingredient in aquafeeds.

Heat shock proteins (Hsps) can promote integrity of damaged intestinal epithelial tissues. The aim of this study was to determine the effects of a commercially available anti-phospholipase A2 antibody on growth, feed efficiency, Hsp expression, and intestinal health of rainbow trout fed diets containing high levels of soybean meal (SBM). Six practical-type diets (45% protein; 15% fat) were formulated to contain 0, 17.5, or 35% SBM with and without antibody. Each diet was fed to three replicate tanks of fish (20 fish/tank; initial weight 21 g) for 9 wk. RNA was isolated from liver and intestinal tissues (n = 3/tank) to detect alterations in Hsp 27, Hsp 70, and Hsp 90 expression. Fish fed a diet containing 35% SBM had decreased growth and intestinal damage. Hsp 27 and Hsp 90 mRNA was elevated in fish fed 35% SBM. Fish fed 35% SBM with antibody had lower Hsp 90 mRNA expression than fish without antibody. These data indicate that feeding rainbow trout high levels of SBM alters the expression of some Hsps and anti-phospholipase A2 antibody supplementation does not normalize growth or prevent distal enteritis in fish fed 35% SBM.

The potential benefits of selenium (Se) supplementation are currently under investigation for prevention of certain cancers and treatment of neurological disorders. However, little is known concerning the response of the brain to increased dietary Se under conditions of Se sufficiency, despite the majority of Se supplementation trials occurring in healthy, Se sufficient subjects. We evaluated the transcriptional response of Se-dependent genes, selenoproteins and the genes necessary for their synthesis (the selenoproteome), in the zebrafish ( Danio rerio) brain to supplementation with nutritionally relevant levels of dietary Se (sodium selenite) during conditions of assumed Se sufficiency. We first used a microarray approach to analyze the response of the brain selenoproteome to dietary Se supplementation for 14 days and then assessed the immediacy and time-scale transcriptional response of the brain selenoproteome to 1, 7, and 14 days of Se supplementation by quantitative real-time PCR (qRT-PCR). The microarray approach did not indicate large-scale influences of Se on the brain transcriptome as a whole or the selenoproteome specifically; only one nonselenoproteome gene (si:ch73-44m9.2) was significantly differentially expressed. Our qRT-PCR results, however, indicate that increases of dietary Se cause small, but significant transcriptional changes within the brain selenoproteome, even after only 1 day of supplementation. These responses were dynamic over a short period of supplementation in a manner highly dependent on sex and the duration of Se supplementation. In nutritional intervention studies, it may be necessary to utilize methods such as qRT-PCR, which allow larger sample sizes, for detecting subtle transcriptional changes in the brain.

Glycation occurs when glucose reacts non-enzymatically with proteins. This reaction depends upon time, ambient glucose concentration, and the molecular conformation of reactive amino acids. Little is known about protein glycation in fishes and the main objective of this study was to measure glycated hemoglobin (GHb) in rainbow trout, a glucose-intolerant species, under normoglycemic and hyperglycemic conditions. We also identified GHb isoforms in vivo and analyzed the structural environment surrounding potential glycation sites. Despite similar glycemia to healthy humans, GHb was an order of magnitude lower in rainbow trout (0.6%) compared with humans (6%) and was not affected by long-term hyperglycemia. Species differences in GHb appear to be related to differences in erythrocyte glucose, and differential expression and glycation of hemoglobin (Hb) isoforms may explain intraspecific differences in rainbow trout GHb. Computer analysis of glucose isomers (ringed-open and α- and β-pyranoses) interacting with the β-chain of rainbow trout HbI and HbIV, and human HbA did not reveal structural or energetic constraints for glucose binding (the initial step of glycation) for rainbow trout Hbs. Overall, there are significant differences between Hb glycation in humans and rainbow trout, and GHb does not appear to be an accurate indicator of glycemia over time in rainbow trout.

The purpose of this study was to evaluate the replacement of fish meal (FM) with soybean meal (SBM) in diets for juvenile spotted rose snapper with the overall goal of identifying practical diet formulations for commercial production of the spotted rose snapper. The response of spotted rose snapper to diets contained graded levels of FM was evaluated by measuring weight gain, feed efficiency, body composition and blood chemistry during a 12-week period. Four diets were formulated (43.7% crude protein, 14% crude lipid and 19.6 kJ g− 1 gross energy) with 0, 20, 40 or 60% SMB protein replacing FM in diets. Diets were fed to juvenile spotted rose snapper (mean initial weight 17.75 ± 0.03 g) for 12 weeks, and weight gain, feed efficiency, body composition and blood chemistry were assessed at the end of the feeding trial. Compared to the FM diet, there were no significant differences in weight gain, individual feed intake, specific growth rate or protein efficiency ratio (PER) of fish when 20% of the FM was replaced compared to fish fed the FM control diet. However, fish performance was reduced at higher levels of FM replacement, significantly so at the 60% replacement level. Hematological parameters were similar among the treatments. Fish fed the 60% SBM diet had significantly lower lipid levels than fish fed the other diets. There was no significant difference in survival of fish fed the different diets. A second order polynomial regression revealed maximum growth of the spotted rose snapper fed up to 19.4% SBM inclusion. The results of this study show that SBM is an acceptable ingredient to supply 20% of protein in spotted rose snapper diets, but that higher dietary levels reduce fish performance.

Article history:Received 3 April 2012Received in revised form 6 May 2012Accepted 8 May 2012Available online 15 May 2012Keywords:FishmealPlant proteinSoy protein isolateBranched chain amino acidsGene expressionTOR Theobjectiveofthestudywastoevaluatetheeffectofdietaryproteinsourceonfishgrowth,nutrientutilization,plasma variables and hepatic gene expression in juvenile rainbow trout (Oncorhynchus mykiss). Fishmeal (FM)and soyprotein isolate(SPI)wereusedasthemainsourcesofprotein insixisonitrogenous,isolipidicandisoca-loric diets. The amino acid profiles of the diets were completely balanced to minimize differences betweenexperimentaltreatmentsandformulatedtocontainincreasinglevelsofbranched-chainaminoacids(BCAA)based upon dietary requirements for trout (NRC, 1993). Dietary protein source more consistently changed themeasured variables while BCAA supplementation had an unexpected effect over whole body lipid content.Growth performance and protein retention ef ficiency were significantly reduced in fish fed SPI diets indepen-dently of BCAA supplementation. Total concentration of amino acids as well as circulating indispensable aminoacids (IAA) were significantly elevated in the plasma of fish receiving SPI diets compared to fish fed FM diets.ThechangeinIAAwaslargeenoughtoincrease(pb0.05)plasmaIAA/DAA(DAA:dispensableaminoacids)pro-portion even when the diets were formulated to have a ratio close to 1. Levels of circulating BCAA and alaninewerealsoelevatedinthefishfedSPIdiets,possiblyindicatingachangeinproteinturnover.TheuseofSPIcausedareduction(pb0.05) inthe hepatic expression levelsofalanine amino transferase(alt1) and glutamine synthe-tase2 (gls02),whileanincreasewasobserved for aspartate aminotransferase (got2),and asparaginesynthetase(asns)comparedwithFMdiets.Expressionofthegenetor(targetofrapamycin) declinedovertimeforalltreat-ments, while expression of a gene known to repress tor function, redd-1, was consistently higher in the liver offish fed SPI diets. Glucose 6 phosphate dehydrogenase (g6pd) also showed a significantly higher expression inthe liver of fish fed SPI diets but only at higher levels of BCAA supplementation.In summary dietary protein source has a significant effect over growth performance, body composition and he-patic gene expression in rainbow trout. We also identified for the first time in fish changes in the expression ofredd-1, which may represent another regulatory point in the TOR cascade.© 2012 Elsevier B.V. All rights reserved.

Fish meal may contain “unknown growth factors” that have yet to be identified for their physiological role. Carnosine is a histidine-β-alanine dipeptide found in muscle and nervous system tissue which has been demonstrated to have biological activity, but its physiological role is not well defined. A 9-week feeding study was conducted comparing diet FM, a 100% fish meal protein control diet, to fish fed three plant protein diets: diet SPI, 100% of the fish meal replaced with soy protein isolate; diet SPI + AA, diet SPI supplemented with methionine, lysine, threonine and glycine to diet FM levels; and diet CSN, diet SPI + AA supplemented with carnosine. Feeding diet SPI resulted in significant differences in feed conversion ratios (FCR), percent gain and protein retention efficiencies relative to fish fed diet FM. Feeding diets SPI + AA and CSN resulted in FCRs, percent gains and protein retention efficiencies that were not significantly different from fish fed diet FM. Fish fed diets SPI, SPI + AA and CSN resulted in reduced muscle ratio (MR) and feeding diets SPI + AA and CSN resulted in increased intraperitoneal fat ratio (IPFR) relative to fish fed diet FM. Supplementing carnosine to an all-plant protein diet resulted in elevated plasma carnosine and increased muscle free pool anserine. Feeding diets SPI, SPI + AA and CSN resulted in reduced muscle development and increased calpain induced proteolysis. In conclusion, carnosine supplementation did not significantly improve the 100% plant protein diets in regard to the measured growth characteristics above the amino acid supplemented treatments and other unidentified factors may be limiting in the diet causing the reductions in MR and elevated IPFR.

The purpose of this study was to evaluate blends of alternate proteins as replacements for fishmeal in diets for rainbow trout (Oncorhynchus mykiss) and to use the results to develop and test alternate protein blends in diets for juvenile Atlantic salmon (Salmo salar). Nine experimental diets in which protein blends replaced 63%, 82% or 100% of fishmeal in the formulation (20, 10, and 0% fishmeal) were fed to rainbow trout (initial weight 19.5 g) for 12 weeks. Weight gains of trout fed diets containing the soy protein concentrate-based blend and the fishmeal control diet were similar, except at the 100% fishmeal replacement level, and significantly higher than that of trout fed diets containing the other blends. The soy protein blend and another based on wheat gluten meal were modified slightly and evaluated in early stage Atlantic salmon juveniles (initial weight 5.5 g). Protein blends replaced 50%, 66% or 84% of fishmeal (30, 20 or 10% fishmeal). Weight gains of early stage juvenile salmon after 18 weeks of feeding were significantly lower and feed conversion ratios higher when fed diets containing either blend compared to the fishmeal control diet, and gains decreased as level of fishmeal replacement increased. Blends were then modified further and tested in advance stage salmon juveniles (initial weight 31.5 g). These blends were solely either all-plant protein-based or contained poultry by-product meal. Both blends were evaluated with or without addition of Spirulina algae meal. Alternate protein blends completely replaced fishmeal in experimental diets. After 12 weeks of feeding, no differences in weight gain or feed conversion ratios were measured among groups fed experimental diets containing protein blends or the fishmeal control diet. Replacement of fishmeal with alternative protein blends in diets for early stage juvenile salmon is not recommended and the penalty in growth is severe. Fishmeal can be completely replaced in diets for late stage salmon over 30 g without compromising fish performance or using land animal protein ingredients in feed formulations.