Abstracts now available

We have just posted the abstracts/summaries of the presentations to be given at Aquafeed Horizons 2011.

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Effects on performance and product quality in Atlantic salmon fed diets reduced in organic pollutants

Jan Olli¹, Bente Ruyter², Turid Mørkøre^2, Harald Breivik³, Aimo Oikari⁵, Aleksei Krasnov², Olav Thorstad⁴, Åshild Krogdahl⁶ , Gunnar Berge⁸ and Torbjørn Åsgård^7*

¹ AVS Chile SA, Casilla 300, Puerto Varas, Chile

² The Norwegian Institute of Food, Fisheries and Aquaculture Research (Nofima), P.O. Box 5010, NO-1432 Ås, Norway

³Neperdo™ Biomarine, Porsgrunn, Norway

⁴ Pronova,BioPharma P.O Box 2109, NO-3202 Sandefjord, Norway

⁵University of Jyväskylä, , P.O.Box 35, FIN-40014 Jyväskylän yliopistoy

⁶Norwegian School of Veterinary Science, Oslo, Norway.

 ⁸Pronova,BioPharma P.O.Box 420, 1327 Lysaer, Norway.⁷ The Norwegian Institute of Food, Fisheries and Aquaculture Research (Nofima), NO-6600 Sunndalsøra, Norway

Oily fish, including Atlantic salmon, due to their content of omega-3 fatty acids, are considered healthy for human consumption. However, marine raw materials used in fish diets are considered a major source of persistent organic environmental pollutants (POPs). Advice regarding fish consumption has therefore been complicated by reports that some species are burdened with potentially harmful levels of POPs, such as dioxins, PCBs and brominated flame retardants (BFRs). Despite the rather low levels of environmental pollutants found in farmed Atlantic salmon, there is still some concern about the levels found. One should therefore aim at reducing the level of POPs in aquacultured fish, in order to strengthen the “healthy image” of the product. As a way to reduce these POPs in farmed fish, Pronova

BioPharma Norge AS has developed a short path distillation process using a volatile working fluid efficiently removing POPs from fish oils. Potential beneficial effects in the farmed fish from reducing the POPs in the feed oil, were tested in a study lasting from post smolt size to slaughter size at Gildeskål Research Station (GIFAS), Norway. The fish were given feeds containing purified or not purified fish oil, four replicates per treatment. The effects on growth, health and fillet quality were studied. There was a tendency for better growth and feed utilisation in the group receiving feed containing purified oil. This was particularly the case during periods of high growth when both the growth rate and feed utilisation rate were significantly better for the fish that received the feed containing purified oil. The salmon that received the feed containing purified oil appeared to better tackle the handling stress during the slaughtering process, measured as a delayed pH reduction after killing. Other stress markers showed the same tendencies. All the fish in the trial maintained a good red colour and firmness, but there was a tendency that fish that received the feed containing purified oil had a firmer texture. The difference in texture was most pronounced after freezing. The proportion of salmon with soft texture was then halved in comparison to the fish that received unpurified oil.

Improved P utilization of marine feed resources

Sissel Albrektsen, Kaspar Thorsen and Halvor Nygård

¹ Nofima, Kjerreidviken 16, N-5141 Fyllingsdalen, Norway

Sissel Albrektsen, Kaspar Thorsen and Halvor Nygård

Phosphorus (P) is an essential element for normal energy metabolism, skeletal development and growth in fish. The main natural source of P in commercial fish feeds are fish meals and fishery products. In fish bones, P is mainly present in a complicated crystal structure with Ca known as hydroxyapatite ((Ca- PO₄) OH₂) and as constituent of Ca₃(PO₄)₂ which must both be hydrolysed into simple phosphates for intestinal absorption. Fish have limited and variable ability to digest P from fish meal (~10 – 80 %), Cho and Bureau (2001), making it difficult to predict that adequate P is present for normal growth and health of fish. The low capacity for P digestion especially in salmonids releases about 60-80 % of dietary P through faecal and urinary excretion, which is a major environmental concern. In commercial fish farming, addition of soluble P salts in the diet is needed to avoid P deficiency. Expected limitations in rock phosphates in the near future and demand for this non-renewable resource as fertilizer element, has increased cost and the need for developing more P efficient low-pollution feed ingredients in diets for farmed fish.

Nofima Ingrediens has developed a process for alternative processing of the bone fraction of fish meal by separation and hydrolysis to make the minerals more water soluble and available. Improved digestibility (average 60%) has been demonstrated for macro minerals and trace minerals, although the variation in between elements appears to be high. Digestibility of P in fish meal produced from blue whiting has been increased by 70 – 80 % by separation and treatment of the bone fraction in strong acids. Alternative processed fish meals with improved P digestibility have further demonstrated improved growth and skeletal mineralization in salmon similar to that produced by addition of commercial soluble P salts. Selected results from a strategic institute program (NRC project 173499/130: Improved phosphorus (P) utilization of marine feed resources - Dietary impacts and optimal P nutrition in Atlantic salmon and Atlantic cod) related to technological processing of the bone fraction, and to biological performance of salmon fed the P improved feed ingredients, will be presented.

High growth rates in Atlantic salmon (Salmo salar L.) fed 7.5% fish meal in the diet. Micro-, ultra- and nano- filtration of stickwater and effects of different fractions and compounds on Atlantic salmon performance fed very low fish meal diets

Katerina Kousoulaki*¹, Hanne Jorun Olsen², Sissel Albrektsen¹, Eyolf Langmyhr¹, Paddy Campbell², Anders Aksnes^1
1 Nofima Ingredients AS, Kjerreidviken 16, N-5141 Fyllingsdalen, Norway
² BioMar AS

Stick water (SW) separated during fishmeal production from frozen herring was fractionated following successive micro- ultra- and nano- filtration steps. The press cake (PC) produced during separation of the SW and the different SW fractions were combined again to produce 4 fish meals containing different molecular size soluble protein mixes. The SW fractions used for the production of the experimental fish meals were 1) the micro-filtration (MF) retentate, 2) the ultra -filtration (UF) retentate, 3) the nano-filtration (NF) retentate and 4) the nano-filtration permeate. Four very high plant protein experimental diets were prepared using 1 of 4 experimental fish meals containing the different SW fractions. The experimental diets contained in total 75 g kg-1 fishmeal, of which 25 g kg-1 diet was superprime fish meal (SP) and 50 g kg-1 diet was 1 out of 4 experimental fish meals. The remaining dietary protein sources consisted of a mixture of commercial plant protein raw materials in equal amounts between the low fish meal experimental diets (soy protein concentrate 235 g kg-1 diet, corn gluten 235 g kg-1 diet; field beans 180 g kg-1 diet; wheat gluten 53.5 g kg-1 diet). A control diet was prepared containing 300 g kg-1 diet commercial fish meal. Three more very low fish meal experimental diets were prepared with 25 g kg-1 diet SP and 50 g kg-1 diet either PC alone or PC and crystalline taurine or crystalline hydroxyproline up to the level present in the high fishmeal control diet. The experimental diets including the SW fractions contained similar levels of water soluble protein (WSP) higher than the PC diets but lower than the control. All diets were iso-nitrogenous, iso-lipidic and iso-energetic and were fed to 8 triplicate groups of salmon (80 fish per group of initial body weight 133 g) for 69 days. High growth rates and low fish in-fish out ratios (FIFO) were achieved in salmon fed all the very low fish meal diets. Feed intake, fish body growth, whole body protein content, protein gain and morphometry were significantly affected by the inclusion of the different SW fractions in the low fish meal diets. We did not find any benefits for salmon performance by the supplementation of taurine or hydroxyproline alone to the low fish meal PC diets. The present work gives evidence on the multi-dimensional effects of the different marine water soluble components in fish performance. In order to identify novel high added value water soluble marine raw materials more studies must be conducted on the identification of specific functional effects of marine water soluble compounds in fish.

The use of seaweeds in aquatic feed

Colin Mair, Technical Director, Ocean Harvest, Ireland

Seaweeds are an under-used natural and sustainable resource in the feed industry, both for aquatic feeds and terrestrial feeds. Analysis of seaweeds shows them to be a rich source of many trace ingredients, as well as having a significant quantity of high quality 'macro' ingredients. Ocean Harvest Technology has been involved in the research and development of a complex mix of seaweed powders that can be used to make a 'chemical-free' feed product, and have shown in rigorous commercial trials with fish and shrimp significant improvements in health, growth rate, feed conversion ratios and resistance to disease.

Aquafeed sourcing, key to successful aquaculture sector

Mrs. Valeska Weymann, GLOBALG.A.P c/o FoodPLUS GmbH/Standard Management Aquaculture, Cologne, Germany

The aquaculture sector requires in most cases the need to supply  compound feed to the farmed organisms for proper growth and health;

 - Aquafeed appropriate sourcing plays a key role in the operational costs;

 - Feed coming from appropriate sourcing refers to: all raw materials used are subject of a risk assessment, including economical, supply chain, safety and ecological assessments;

- In the case that compound feed may contain fishmeal and/or fish oil, the species of fish used and its respective country of origin are desirable to be identified, together with a proof that it does not contain species classified as critically endangered or endangered on the IUCN Red List;

- At processing level: HACCP system shall be in place as well as consideration to workers health and safety;

- Animal protein shall follow legislation of country of production and purchase requirements of country of destination;

- Certification is a tool that compound feed manufacturers can adapt to support the need to demonstrate  responsible sourcing.

Trends in aquafeed: Relevence and technical solutions

Urs Wuest, Head Engineering & Fulfillment, Buhler, Switzerland

Changes throughout the entire aquafeed value chain will impact feed millers in the near future and beyond. Buhler will present the current trends in the Aquafeed industry to ensure feed and food safety and hygiene. This will include the changes in raw materials, feed manufacturing, aquaculture, processing of the fish and crustaceans and the demand from customers in total and by fish species. Further will be explained how changing requirements in the aquafeed industry translate into a demand for specific technical requirements, such as extrusion technology.

Planning a Strategic Path for Feed Safety in Aquafeed Plants

Joseph P Kearns, Aquaculture Process Engineering Manager, Wenger Mfg., Inc., USA

The developing trend in aquafeed plants is to insure feed safety throughout the production process.  A strategic path to accomplish this would be to assess and design the facility with attention to the following areas:  raw materials and their storage, plant equipment design, processing or operating procedures, final product efficacy and the overall culture or day to day operation of the plant.

Hygienic design principles for aquafeed plants and the equipment should be designed to achieve a cleanable HACCP level.  The equipment should be constructed of compatible materials with accessibility for cleaning and inspections with no material collection points or niches.

The way forward in aquafeed production safety is to strive to identify and validate critical control points in the process and operate on that basis.  Avoid recontamination in downstream areas after the critical points and install a finished product testing procedure for validation.

Multivariate modelling of extruded fish feed pellet quality

Tor Andreas Samuelsen ^1*, Svein Mjøs^1,2, Åge Oterhals¹

¹Nofima Ingrediens, Bergen, Norway

² Department of Chemistry, University of Bergen, Norway

Physical quality of extruded fish feed have become more important due to the use of bulk transport and pneumatic feed delivery systems. The complexity of the extrusion process, and limitations in basic knowledge on protein properties and protein/starch-interaction, make it a demanding task to obtain consistent product quality based on different types of raw materials. Changes in feed mash properties might lead to large quantities of feed pellets that are not consistent with product specifications and give increased production costs due to reprocessing needs or customer complaints.

Fishmeal at high inclusion level is a critical protein ingredient with respect to aqua feed processing and has a significant impact on pellet physical quality. Fishmeal is produced by use of heat coagulation combined with a mechanical and thermal dewatering process. 

We have studied the impact on pellet hardness and durability of commercial fishmeal parcels combined with low, medium and high water and steam input levels in the extrusion process.  Commercial fish meal parcels with a large variation in chemical composition and physical properties were produced from high quality herring at three different fishmeal factories in Norway. The experimental feed mixtures were processed on a Wenger TX-52 extruder at three moisture levels. The fishmeal quality was assessed based on 18 quality parameters and prediction models for pellet hardness, specific mechanical energy (SME) and starch gelatinization established based on partial least squares regression (PLSR) modeling. The study documented the possibility to develop a model explaining pellet hardness based on chemical and physical properties of fish meal and steam/water level in the process. The work also demonstrated that fishmeal physicochemical properties and added moisture had a significant effect on the melt viscosity and thereby dissipation of mechanical energy in the extruder barrel.

The information can be used by the aquatic feed industry to better understand and correct the observed variance in extrusion properties and pellet quality and to improve the product specifications used by fish meal producers and purchasers. Examples on how the knowledge can be used to solve problems in the extrusion process will be discussed.

Optimal pellet quality is a trade-off between durability and responses in the fish

T. Synnøve Aas^1,5*, Bendik F. Terjesen¹, Trygve Sigholt³, Marie Hillestad³, Jørgen Holm⁴, Ståle Refstie^1,6, Grete Baeverfjord¹, Kjell-Arne Rørvik², Mette Sørensen^2,6,7, Maike Oehme^1,5, Gaojie He^5,7, Torbjørn Åsgård^1,5

¹ Nofima, NO-6600 Sunndalsøra, Norway

² Nofima, Postboks 5010, NO-1432 Ås, Norway

³ BioMar, AS, NO-7484 Trondheim, Norway

⁴ BioMar A/S, Mylius Erichsensvej 35, DK-7330 Brande, Denmark

⁵ Centre for research based innovation in aquaculture technology (CREATE), SFI, SINTEF Sealab, NO-7645 Trondheim, Norway

⁶ Aquaculture Protein Centre (APC), CoE, P.O.Box 5003, NO-1430 Ås, Norway

⁷ Norwegian University of Life Sciences (UMB), Department of Animal and Aquacultural Sciences, P.O. Box 5003, NO-1432 Ås, Norway

Handling, storing and transport of feeds lead to attrition of the pellets. Undersized particles represent loss and poor utilisation of feed resources. Thus, feeds with high physical pellet quality are demanded. However, the physical properties affect the nutritional value of feeds. In a 48 days trial, two feeds, with high (feed A) or low (feed B) water stability, were fed to rainbow trout (Oncorhynchus mykiss) kept in sea water (salinity 32-34 ppm, temperature 12 °C, O2-saturation >80%). The feed intake was 23% higher in trout fed feed B than in those fed feed A. Introducing a daily period of lowered salinity (< 10 ppm), temperature (6 °C) and oxygen saturation (50-60%) resulted in a severe drop in feed intake in both dietary groups. However, the apparent digestibility of macronutrients was highest in feed A, but at fluctuating environment the difference between the dietary treatments was small. Furthermore, the stomachs of trout fed feed B, particularly of those kept at stable environment, contained large amounts of free water and oil, which could potentially lead to fat belching. Both apparent digestibility and free water and oil in the stomach seemed to be related to feed intake, and were thus indirectly caused by feed and environmental conditions. In another trial, pellet degradation of three commercial feeds (12 mm pellet size) during pneumatic conveying, which is commonly used in cage culture to transport the feed from the storage silo to the sea pens, was measured. The three feeds, chosen especially for having different physical properties, showed different degradation patterns during conveying. Furthermore, high air speed (m/s) in the conveying system, which is used to spread the feed pellets well in the cage, increased pellet degradation, whereas high feeding rate (kg/min) protected the pellets from breakage. In all runs, less than 1% of the sample ended up as small particles. In conclusion, feed intake appears to be a main factor when evaluating pellet quality, but several other factors, such as pellet durability, nutrient digestibility and fat belching must be taken into consideration when searching for the most economical and sustainable pellet quality.