Minimizing marine resource utilization in diets of farmed Atlantic salmon (Salmo salar): effects on growth performance and muscle, liver, and head kidney chemical composition

Foroutani, Maryam Beheshti (2017) Minimizing marine resource utilization in diets of farmed Atlantic salmon (Salmo salar): effects on growth performance and muscle, liver, and head kidney chemical composition. Masters thesis, Memorial University of Newfoundland.

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Abstract

Due to the limited availability of fish meal and fish oil resources and their high costs in producing aquafeeds for the aquaculture industry, it is important to conduct research on possible replacements that are sustainable sources of protein and lipids. In this study, seven different diets containing various protein and lipid sources were formulated to feed farmed Atlantic salmon, and their effects on growth performance, tissue lipid class, fatty acid, and elemental composition were examined. Growth performance results showed that the diet containing the lowest level of fish meal and fish oil led to the lowest weight gain, followed by the diet with the highest content of animal by-products. The lipid class analysis for the three examined tissues (muscle, liver, and head kidney) showed no statistical difference in the total lipid content using the seven dietary treatments. However, there was a statistical difference between the main lipid classes; triacylglycerols, phospholipids, and sterols. The elemental analysis of the three tissues revealed a higher ratio of carbon to nitrogen (C/N) in head kidney tissues compared to muscle and liver tissues, which consequently resulted in the highest level of total lipids in head kidney tissues. The carbon and nitrogen analysis of the liver tissues showed that diet with 1.4% ω3 long chain fatty acids (ω3LC1.4) resulted in a higher nitrogen concentration and a lower C/N ratio than when other dietary treatments were used. In terms of essential fatty acids, liver and head kidney tissues of fish fed the diet with lowest amount of fish meal and fish oil had the lowest EPA and DHA and the highest ARA levels. Diets with low levels of fish meal and a medium level of fish oil, resulted in as high a level of ω3 fatty acids in the examined tissue as when diets containing high levels of fish meal and fish oil were used. This study suggests that fish meal can be reduced to 5% without affecting growth as long as there is a minimum of 5% fish oil, and animal by-products do not exceed 26% of diet. It was concluded that reducing fish meal and fish oil to less than 10% in diets of farmed Atlantic salmon affects growth performance, as well as elemental, lipid, and fatty acid compositions of the muscle, liver, and head kidney tissues.

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