Food safety and the use of terrestrial animal by-products in Atlantic salmon production

Farmed Atlantic salmon have traditionally been fed diets containing large amounts of fish oil and fishmeal. The steady increase in production volume in aquaculture has resulted in increasing use of alternative proteins and oils in aqua feeds. Sustainable fish farming includes the use of diets formulated using economical, suitable and ethical acceptable feed ingredients. On a global basis, processed animal products (PAP) from the rendering industry constitute one of the largest sources of high quality animal protein available for animal feed production. The use of PAPs such as feather meal, poultry by-product meal, pork meat and bone meal, and poultry and pork blood meal have been shown to be relevant nutritional replacements of fish meal for many cultured fish species including salmonids. However, following the peak outbreaks of transmissible spongiform encephalopathies, or mad-cow disease in the UK in the early 1990?s, the use of all PAPs in all animal feed was banned in the European Union. In 2013 the use of none-ruminant PAPs were re-authorized for use in animal feed, initially for aquafeeds. Research on food safety of farmed salmon reared on PAP-feed is an important step for the implementation of PAP ingredients for Norwegian salmon feed and vital to ensure safe production of seafood from farm to fork. The main topics for the safety of PAP-reared salmon include; 1) the tissue and species-specific identification of PAPs, 2) full overview of the presence of a wide range of new chemical residues derived from terrestrial animal farming, 3) the potential carry-over of these contaminants to the salmon food production chain. In addition to NIFES, the partners in the present project included the European Reference Laboratory (EURL) for PAPs in Belgium (CRA-W), commercial laboratories for PAP identification in the Netherlands (NutriControl), representative of the rendering industry (EFPRA), University sector on contaminant analyses in Spain (University JaumeI-IUPA), the public health institute of the Netherlands for food-chain risk modelling (RIVM), and research and development sector of a Norwegian salmon feed producer (EWOS-Innovation). In order to avoid the reintroduction of ?mad-cow? disease, processed animal proteins from ruminants are not allowed to be used in animal feeds. To assure the absence of ruminant PAP material in PAP based aquafeeds, a European Union Reference Laboratory (EURL) validated DNA based method has been implemented. However, the DNA method does not allow for a differentiation of cellular origin, and hence cannot be used for tissue specific (i.e. bone, feather) identification. This tissue identification is helpful for trying to find a source of contamination. In the present project a method was developed based on peptides that allowed the identification of both species (cow, pig, or chicken) as well as the tissues (blood, brain, meat). To establish this method a total peptide profile of 19 commercial PAP samples was made by mass spectrometry, creating a ?big data? data base on the overall peptide composition of these PAPs. With use of bioinformatics those peptides that differentiate the PAP samples based on species and tissue could be identified. This provides a tool to identify the source (and hence source of possible contamination) of PAP used. Furthermore, commercial alternative methods to identify ruminant material were tested on salmon feeds. The immunoassay-based methods did not seem to have a low enough limit of detection for aquafeeds, while their limit of detection was good enough to be directly used on pure non-ruminant PAP samples. The use of PAPs in salmon feed can potentially introduce new chemical undesirables that have not been previously associated with farmed Atlantic salmon. Of special interest are pharmaceuticals such as antibacterials, which are used in all sectors of farming,including poultry and swine production. In the present project a wide scope screening method was developed that could screen for more than 100 pharmaceutical compounds in 19 commercial available PAP samples. With this screening method the presence of nine low back-ground levels of anti-fungi/dyes and antibiotics were identified in commercial available PAPs. To investigate whether the low background levels of prohibited dyes such as leuco-crystal violet and malachite green could be transferred from feed to the edible part of the fish a feeding trial was performed in which the uptake and elimination rates of these substances was established. Based on the uptake and elimination rates a 3 compartmental model was developed that can predict the levels of these unwanted substances in the fillet of a salmon during a whole production cycle.

The project will assess the risks involved in using rest products from farmed land animals (processed animal proteins; PAP) in novel salmon feeds. The project will develop novel tools, both analytical as well as risk assessment tools, which will be used i n the advisory role NIFES has to the Norwegian Food Safety Authorities on salmon feed and seafood safety. The project will assess emerging risk throughout the whole Atlantic salmon food production chain when using PAP salmon feeds, with focus on both feed and food safety. The project will have participation of the industry that is producing nutritional PAP products as well as the industry that intends to implement these rest products in the innovation of novel salmon feeds. The project will have participa tion of the European Union reference laboratory on PAPs as well as the national research institute that performs surveillance and advises the Norwegian Food authorities on fish feed and food safety. Research on food safety of farmed salmon reared on PAP -feed is an important step for the implementation of PAP ingredients for Norwegian salmon feed producers and vital to ensure safe production of seafood from farm to fork. The main topics for the safety of PAP-reared salmon include; 1) the species-tissue s pecific identification of PAPs, 2) full overview of the presence or absence of a wide range of new chemical residues derived from terrestrial animal farming, 3) the potential carry-over of these contaminants to the salmon food production chain. The prese nt proposal aims to: A) Validate and develop novel genomic and peptidomic methods as well as screening methods for species and tissue specific identification of PAPs B) Perform state-of-the-art screening of numerous chemical residues in relevant PAPs fo llowed by quantification of identified contaminants C) Assess the transfer of PAP-derived chemical residues from feed to the edible part of farmed salmon as well as establishing predictive feed-to-fillet carry-over