Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

The Norwegian Food Safety Authority (Mattilsynet) asked the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet) to assess if the criteria for safe use of plant ingredients in diets for aquacultured fish fulfil the Feed regulative §7 to “not induce negative health effects in the animal”, and in this context aquacultured fish. The use of feed ingredients of both plant and animal origin is set by the regulation “Forskrift 7. November 2002 nr 1290”, and amendments. The objective of the regulation is to protect animals, consumers and the environment. For animals, the feed shall not pose a risk, or danger, to their health. Aspects to be assessed were whether the changes in fish diet ingredient composition seen in recent years with high levels of plant ingredients, plus additions of immunostimulants, would in any manner challenge fish health and if any ingredient should be limited due to its negative effect, or induce any long-term negative effect. “Long-term” here extends beyond normal production time for consumption, e.g. when substances that might affect fish health are included in broodstock diets. Atlantic salmon (Salmo salar), rainbow trout (Onchorhyncus mykiss), Atlantic halibut (Hippoglossus hippoglossus) and Atlantic cod (Gadus morhua) should especially be addressed. However, since all life stages should be included, especially broodstock, and also possible long-term effects, and literature on these for the requested species is scarce, the assessment mentions studies on other species when relevant. With the exception of full-fat and extracted soybean meal for salmonids, substituting at least part of the fishmeal fraction of aquafeeds with individual plant ingredients is promising, at least in the short to medium term. Indeed in some cases, diets containing up to 20% inclusion level of high-quality plant protein sources have resulted in better nutrient digestibility and growth parameters than the fishmeal-based control diets. When substituting fishmeal with plant ingredients, however, it is necessary to balance the diets regarding limiting amino acids and minerals. Adding plant proteins to fish diets result in the introduction of anti-nutritional factors. There is an urgent need to investigate consequences of various anti-nutritional factors, individually and in combinations, to nutrient digestibility, utilization and metabolism as well as to intestinal function, structure, defence mechanisms and microbiota. Long-term effects also merit investigation. This will aid in the ability to predict how a newly introduced plant ingredient as well as combinations of plant ingredients may affect the fish and identify steps needed to avoid adverse health effects. As many of the potential disadvantages of using plant oils in salmonid diets are related to either very high levels of n-6 PUFA (most available oils) or very high levels of linseed oil, it would be recommended that mixtures of plant oils should be used as feed inclusions. By adjusting the ratio of n-6 and n-3 the level of eicosanoids can be controlled. By including palm oil, potential problems in lipid digestibility and transport can be controlled. A standard inclusion of soybean lecithin may also be advisory. These and other variants of mixtures of oil sources have been explored in recent years with some success in salmonid fish. Such mixtures do not seem to be necessary for marine fish. Modern finfish aquaculture faces problems such as bone and skeletal deformities, cataracts, heart disorders, unspecific ulceration and various digestive disorders including intestinal colic in Atlantic cod, gastric dilatation (bloat) in rainbow trout, and intestinal tumours, at low incidence, in Atlantic salmon broodstock. Most of the mentioned problems have been related to malnutrition, feed, intensive growth and/or unfavourable environmental conditions. The disorders are often not lethal, but may imply a fish welfare problem and increase the susceptibility to secondary disorders and infectious diseases. Major changes in feed composition and feed ingredients may increase the risk for such production-related disorders in intensive fish farming. Care should be taken when choosing plant alternatives, both types and qualities, to prevent nutrition-related diseases such as skeletal deformities, cataracts, heart conditions, and other, unspecific symptoms. The change from marine- to plant-based diet ingredients, results in changed profile and content of undesirable substances. The list of undesirable substances included in the feed legislation is, in general, sufficient, but it should be considered to include pesticides in use today and more of the mycotoxins. Currently only aflatoxin B1 is included, while only recommendations exist for other mycotoxins. Studies of dietary exposure to undesirable substances, e.g. pesticides and mycotoxins, and their toxic effects and toxicokinetics in fish are scarce. To date, the application of pre- and probiotics for the improvement of aquatic environmental quality and for disease control in aquaculture seems promising; however, the information is limited and sometimes contradictory. Currently there are numerous gaps in existing knowledge about exogenous nucleotide application to fish including various aspects of digestion, absorption, metabolism, and influences on various physiological responses, especially expression of immunogenes and modulation of immunoglobulin production. As limited information is available about the effect of immunostimulants, prebiotics and nucleotides on gut morphology, this topic should be given high priority in future studies. Heat processing of raw materials and of the complete fish diets may potentially alter nutritional properties of plant materials. However, the negative effects appear to be modest under practical conditions.

Benefit-risk Assessment of Fish and Fish Products in the Norwegian Diet – An Update.

Request from the Norwegian Food Safety Authority (NFSA) In September 2013, the Norwegian Food Safety Authority requested VKM to update relevant parts of the benefit-risk assessment of fish in the Norwegian diet published by VKM in 2006. The background for the request was new knowledge and data on the content of some nutrients and contaminants both for wild and farmed fish since 2006. The proportion of vegetable ingredients used in farmed fish feed has in recent years increased, and new national dietary surveys for adults and children have been conducted. The Norwegian Food Safety Authority referred to VKM’s report from 2006, which pointed out that the positive impact of fish consumption on public health was especially due to the content of polyunsaturated fatty acids and vitamin D in fish. Further, VKM concluded that the contaminants that could pose a potential risk to public health through fish consumption mainly were methylmercury, dioxins and dioxin-like PCBs (dl-PCBs). The request included a reassessment of fish consumption in Norway with focus on specific nutrients; n-3 fatty acids (eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), vitamin D, and the minerals iodine and selenium, and on specific contaminants; mercury, dioxins and dl-PCBs. VKM was asked to address the main changes in the use of raw materials in farmed fish feed and how these affect the levels of nutrients, mercury, dioxins and dl-PCBs and in fish feed. Further, VKM was asked to address to what extent levels of nutrients and contaminants in fish have changed since 2006, to describe these changes and estimate the human intake of the substances in question on the basis of recent dietary data. VKM was also requested to consider the benefits of eating fish with regard to the intake of nutrients and the risks associated with the intake of mercury, dioxins and dl-PCBs and comment on whether this change the conclusions from the report in 2006. Additionally, on the basis of updated knowledge, VKM was asked to comment whether other substances, like pesticide and residues of veterinary medicinal products, could affect the conclusions with regard to the impact on public health. The Norwegian Food Safety Authority and the Directorate of Health will use the updated assessment as a basis for public recommendations concerning the consumption of fish and fish products. How VKM has Addressed the Request The VKM appointed a working group consisting of VKM members and external experts to answer the request. Several of the scientific panels of VKM reviewed the report during its preparation. The Scientific Steering Committee of VKM has given their final assessment and approval of the current report. In the current report, VKM has mainly used data from national surveillance and monitoring programs for nutrient and contaminant concentrations in fish feed, farmed fish and wild caught fish, but occurrence data have also been derived from peer reviewed articles. VKM has estimated fish consumption in three population groups (2-year-olds, adults and pregnant women). The estimated fish consumption was compared to national dietary guidelines. To assess health effects of fish consumption, the current estimated fish intakes were also compared with assessments done by recognised international bodies and results from epidemiological studies addressing possible associations between fish consumption and specific health outcomes. Literature searches were done to identify relevant epidemiological studies. VKM has not systematically assessed reviews or meta-analyses nor individual studies for weight of evidence, but merely summarised the studies retrieved from the literature search. It was considered being beyond the scope of this assessment to review individual studies included in reviews or meta-analyses. Furthermore, based on current fish consumption in the various population groups, intake of nutrients and exposure to contaminants from fish were estimated. For benefit characterisation of the specific nutrients the estimated nutrient intake was compared with national recommendations of nutrients intake and for EPA and DHA a comparison was also done with European recommendations. For risk characterization of contaminant exposure from fish, VKM used health based guidance values set by international risk assessment bodies (WHO, EFSA). VKM noted that the request from NFSA was restricted to fish, whereas the VKM report in 2006 included both fish and other seafood. VKM focused on specific nutrients and contaminants as requested by the NFSA. In addition, VKM also commented on other substances that could affect the risk assessment, such as residues of veterinary medicinal products including residues of antibiotics, new contaminants from fish feed like the pesticide endosulfan, polycyclic aromatic hydrocarbons (PAHs), mycotoxins, the synthetic antioxidants ethoxyquin, butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT), as well as environmental contaminants like brominated flame retardants and perfluorated organic compounds Background In the Norwegian diet fish is important source of well-balanced proteins, and important nutrients such as EPA and DHA, vitamin D, iodine and selenium. On the other hand, fish is also a source of exposure to chemical contaminants like dioxins, PCBs and mercury. Over the last 10 years there has been a great change in raw materials used in fish feeds, and in 2013 terrestrial plant proteins and vegetable oils accounted for 70% of the feed. The changes in concentrations of nutrients and contaminants in fish feed for farmed Atlantic salmon and trout are reflected in changed concentrations and compositions of the same nutrients and contaminants in the farmed fish fillet. The current national dietary guideline is to eat fish as dinner meals 2-3 times per week for all age groups, representing 300-450 g fish per week for adults, including at least 200 g fatty fish, such as salmon, trout, mackerel and herring. Fish is also recommended as bread spread. Further, a daily supplement of vitamin D to infants from 4 weeks of age is recommended, and if this supplement is taken as cod liver oil it will in addition ensure an adequate supply of EPA and DHA. The present benefit-risk assessment is comprised of three elements, i.e. benefit assessment, risk assessment and benefit-risk comparison. This methodology is in accordance with the guidance given by EFSA in 2010. Fish Consumption in Norway and Comparison with National Dietary Guidelines VKM has used information about fish consumption from more recent national dietary surveys among 2-year-olds (Småbarnskost 2007) and adults at 18-70 years of age (Norkost 3, 2010/2011), as well as information for pregnant women who answered the Norwegian Mother and Child Cohort Study (MoBa2, 2002-2008) food frequency questionnaire. The national food consumption survey Ungkost 2000, which covers the age groups 4-, 9-, and 13-year-old children, was considered too old to be used and it is therefore not known if their fish consumption patterns have changed, neither in amount consumed nor type of fish consumed. Even though there are methodological differences between the dietary surveys used in 2006 and 2014, the amount of fish consumed appears to be unchanged for all population groups. Furthermore, in 2014, lean fish and fatty fish contribute with about 60 and 40 percent, respectively, of the total fish consumption, which is similar to 2006. Given a portion size of 150 g fish, the average adult eats fish equivalent to 2-3 dinner servings per week and the average pregnant woman eats fish equivalent to 1-2 dinner servings per week, while the average two-year-old eats fish equivalent to 1-2 dinner servings per week given a portion size of 75 g. The table below describes fish intake in the selected populations. Fish consumption (expressed as raw fish), mean grams (g) per week in 2-year-olds (Småbarnskost 2007, n=1674), adults (Norkost 3, n=1787) and pregnant women (MoBa, n=86277) Population groups Mean fish consumption g/week Fish roe Fish, total Lean fish (≤ 5% fat) Fatty fish (> 5% fat) and liver 2-year-olds 112 70 35 7 Adults 364 210 147 7 Pregnant women 217 126 77 14 VKM concludes that of the different population groups, only adults (18-70 years of age) with an average or higher fish consumption reach the national food based dietary guidelines for total fish consumption. Mean total fish consumption and fatty fish consumption in children (2-year-olds) and pregnant women, as well as the mean fatty fish consumption in adults are lower than recommended. In pregnant women and 2-year-olds, fish consumption is too low to meet the food based dietary guidelines Health Effects of Fish Consumption VKM is of the opinion that according to epidemiological studies, the net effects of the present average fish consumption in Norway for adults including pregnant women is beneficial for specific cardiovascular diseases (particularly cardiac mortality, but also with regard to ischaemic stroke, non-fatal coronary heart disease events, congestive heart failure and atrial fibrillation), as well as for optimal neurodevelopment of foetus and infants. Furthermore, VKM is of the opinion that those with fish consumption less than one dinner serving per week may miss these beneficial effects. The health benefit of fish consumption is reported from 1-2 dinner servings per week and up to 3-4 dinner servings per week. For higher fish intake per week, the limited number of consumers in epidemiological studies does not allow for drawing firm conclusions about the actual balance of risk and benefit. More knowledge is needed to reveal the beneficial mechanisms of fish consumption. Benefit Characterisation of Nutrients in Fish VKM is of the opinion that there has been minor or no changes of the composition and concentrations of nutrients in wild caught fish since 2006. Due to replacement of fish oil and fish protein with plant prote

Modeling of drying and adsorption isotherms of the fish feed

The aim of this work was to study the drying curves and equilibrium isotherms of extruded fish feed. The drying curves were determined at air temperatures of 50, 60, 70 and 80°C and airflow velocities of 1.5, 2.5 and 3.5 m/s). The equilibrium isotherms of relative humidity of air were obtained between 10 and 80 percent at 30, 40, 50, and 70°C. The experimental data were fitted for non-linear regression by using Statistica® to the models reported in the literature. The results showed that the drying curves and the equilibrium isotherms were significantly influenced by variations of the air temperature in a similar way to solid materials as described in the literature. The statistical results for models of Page and Peleg showed that the fitting of the experimental drying curve and isotherm data were satisfactory.