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Averoy Field Trials Station Report Library

Title: Salmon Bioassay for Evaluation of Fishmeal Performance

Author: Dr. Laura Martinez Rubio

Background: Although fishmeal levels in typical salmon grower feeds have decreased dramatically since the 1990s, fishmeal is still of strategic importance to the industry. This is on the basis that fishmeal contributes to consistency in salmon performance and makes a valuable contribution to salmon health and quality. Additionally, fishmeal still represents a high proportion of the feed in speciality products including starter feeds and feeds for fish serving speciality markets including the organic and Label Rouge segments. Whilst in vitro tests give an insight into fishmeal quality, there remains a need for some in vivo testing because it gives an insight into the combined effect of all the quality criteria that is still not fully consolidated by the in vitro data alone. In this project, we used a salmon bioassay to explore the quality of four common fishmeal types using salmon performance, feed digestibility and gut health as key performance indicators (KPIs). Click here to view the PDF.


Title: Do Yeast Hydrolysate and Supplementary Marine Phospholipids Work as Aids to Total Fishmeal Replacement in Feeds for Atlantic Salmon, Salmo salar, in the Seawater Production Phase?

Authors: Mia Berwick and Edward King

Background: Numerous explanations for the inconsistency of performance of fishmeal-free feeds have been proposed and both the micro and macronutrient content of fishmeal have been exhaustively recreated in attempts to produce consistently performing fishmeal-free salmon feeds. Part of the character of fishmeal is that it represents a source of both small peptides and phospholipids which, although not considered as essential nutrients, may be important components that a fishmeal-free feed still needs to supply. In this project, we evaluated the impact of supplementing fishmeal-free feeds with hydrolysed yeast and marine phospholipids by comparison to feeds containing different levels of fishmeal. Click here to view the PDF.


Title: Does Dietary Supplementation With an Organic Acid Improve Gut Health and Growth Performance in Atlantic Salmon, (Salmo salar), in the Seawater Production Phase

Author: Martin Røed

Background: Organic acids synthesised by the gut flora of salmon are associated with improved cellular integrity/function and are, therefore, beneficial for the fish’s health. Organic acid production by the gut flora can be encouraged by providing nutrients and conditions that modify or nourish the gut flora e.g. by the application of pre-biotics. An alternative approach is to apply the organic acids directly to the feed in the expectation that they will act directly upon the target tissues of the gut. In this project, we evaluated the potential of an organic acid supplement to improve the gut health of salmon and thereby improve growth and feed utilisation. An additional part of the scope of the project was to evaluate the role played by the degree to which the vegetable protein ingredients have been refined and how the application of an organic acid could facilitate a similar outcome for gut health. Click here to view the PDF.


Title: Comparison of Two Functional Feed Strategies For Optimisation of Atlantic Salmon Health in the Face of Typical, Real-World Challenges to Gill and Skin Integrity

Author: Martin Røed

Background: Farmed salmon inhabit an environment that is rich in challenges to fish health and a substantial proportion of the total cost of farming salmon is associated with maintaining fish health and general resilience. One of the strategies for improving the health and wellbeing of farmed salmon is to increase their robustness through the application of functional ingredients (FIs). Functional ingredients are non-medicinal components in the feed which can be either classical nutrients e.g. vitamin E or feed supplements e.g. purified yeast cell wall components, the consumption of which, is associated with improvements in health, wellbeing or quality. In this study we track changes in skin and gill tissues over an extended period in salmon fed either a feed containing a seasonally tailored, multi-purpose, FI package or a feed with an FI package specifically targeting gill and skin health. Click here to view the PDF.


Title: Evaluation of Whole and Dehulled Field Beans, Vicia faba, as Feed Materials for Atlantic salmon, Salmo salar, in Seawater

Authors: Mia Berwick and Dr Guido Riesen

Background: Being rich in both starch and protein, field beans (also known as horse or faba beans) represent an economic feed material for use in highly nutrient-dense salmon feeds. Being produced widely across Europe and being value-creating as part of a crop rotation system, they represent an opportunity to provide more locally grown, sustainable protein in feeds for European farmed salmon. Dehulling (removal of the outer pericarp and testa of the seed) is a process that can simultaneously increase the starch and protein content and reduce the crude fibre and anti-nutrient content of the beans. Depending on the yield and cost of dehulling, this increases their value in formulation but, access to dehulling facilities creates another complication and/or cost in the supply chain. In this project, we evaluated the utility of both whole and dehulled field beans as feed materials for salmon using a wide array of performance, health and quality indicators. Click here to view the PDF.


Title: Impact of Dietary Digestible Protein Levels and Pellet Size on Growth Performance of Large Atlantic Salmon, Salmo salar

Author: Dr Guido Riesen

Background: It is known that dietary digestible protein (DP) levels are a major driver for growth performance in Atlantic salmon and that dietary DP levels below requirement will reduce growth performance. On the other hand, DP levels above the requirement for optimal growth increase feed cost, reduce profitability and adversely affect the sustainability of salmon farming operations. Changes in environmental and husbandry conditions and improved growth through stock selection are amongst the factors that make periodic reappraisal of the salmon’s DP requirement necessary. Additionally, in fully fed animals, whilst pellet size per-se is not a driver for salmon performance, it is an important factor in the efficiency of feeding which in turn can impact upon the growth and feed conversion ratio (FCR) actually realised in the field. This project represented an opportunity to simultaneously reappraise the digestible protein requirement and to evaluate the impact of pellet size on salmon performance in a semi-commercial environment. Click here to view the PDF.


Title: Impact of Different Lots of the Same Feed Product on Short-term Feed Intake and Growth in Farmed Atlantic Salmon, Salmo salar, at low temperature.

Author: Dr. Ernst M. Hevrøy


Periodically, all fish feed manufacturers receive enquiries related to unexplained changes in feed intake and visible feeding activity in farmed fish. The causes of reduced feeding in practical net pen salmon farming are many and varied spanning everything on a spectrum from season, environment, fish health and the abundance or activity of other animals in the rearing environment e.g. plankton and large predators. Despite the rigorous controls placed on: feed formulation; raw material selection, analysis and quality; the manufacturing process; and post-production quality control and assurance, feed-related variability in feed intake can still occur in farmed Atlantic salmon. In this report, we provide a brief summary of a project in which we compared feed intake for salmon fed two different manufactured lots of the same feed product. Click here to view the PDF.