Abstract
There is an urgent need to find alternative feed resources that can further substitute fishmeal in Atlantic salmon diets without compromising health and food quality, in particular during the finishing feeding period when the feed demand is highest and flesh quality effects are most significant. This study investigates efficacy of substituting a isoprotein (35 %) and isolipid (35 %) low fishmeal diet (FM, 15 %) with Antarctic krill meal (KM, 12 %) during 3 months with growing finishing 2·3 kg salmon (quadruplicate sea cages/diet). Final body weight (3·9 (se 0·04) kg) was similar in the dietary groups, but the KM group had more voluminous body shape, leaner hearts and improved fillet integrity, firmness and colour. Ectopic epithelial cells and focal Ca deposits in intestine were only detected in the FM group. Transcriptome profiling by microarray of livers showed dietary effects on several immune genes, and a panel of structural genes were up-regulated in the KM group, including cadherin and connexin. Up-regulation of genes encoding myosin heavy chain proteins was the main finding in skeletal muscle. Morphology examination by scanning electron microscopy and secondary structure by Fourier transform IR spectroscopy revealed more ordered and stable collagen architecture of the KM group. NEFA composition of skeletal muscle indicated altered metabolism of n-3, n-6 and SFA of the KM group. The results demonstrated that improved health and meat quality in Atlantic salmon fed krill meal were associated with up-regulation of immune genes, proteins defining muscle properties and genes involved in cell contacts and adhesion, altered fatty acid metabolism and fat deposition, and improved gut health and collagen structure.
Highlights
Wild fish harvested from the ocean and reduced into fishmeal and fish oil are finite resources that are shared across a range of users with increasing demands, from direct human consumption, pig and poultry production and to aquaculture feeds[1,2]
The salmon were randomly distributed into eight 125 m3 sea cages at The LetSea feed trial unit in Norway, Dønna county in Northern Norway (100 fish in each sea cage) and fed isoprotein (35 %) and isolipid (35 %) 9 mm feed with 15 % fishmeal (FM group) or a diet where fishmeal was partly substituted by 12 % Antarctic krill meal
Females (4·1 v. 3·7 kg; P < 0·0001), but diets had no effect on final weight, TGC, feed conversion ratio or biometric traits, except for the body shape that was more voluminous of the krill meal (KM) group (Table 5)
Summary
Wild fish harvested from the ocean and reduced into fishmeal and fish oil are finite resources that are shared across a range of users with increasing demands, from direct human consumption, pig and poultry production and to aquaculture feeds[1,2]. The average weight of salmon at harvesting is 4–5 kg[4], and it is important to identify feed ingredients that can replace fishmeal and fish oil during the finishing feeding period when the feed demand is highest It is, vital that fishmeal and fish oil replacers promote similar growth and survival rates to traditional marine aquafeed ingredients and ensure that aquatic animal health and welfare is fostered and that the resultant aquaculture products are nutritionally excellent, safe to eat and accepted by the consuming public[2]. The present study investigates health parameters and meat quality of Atlantic salmon fed a diet where fishmeal was substituted with krill meal during the finishing feeding period with the overarching goal to improve the systemic understanding of dietary krill meal effects on a biochemical, morphological and molecular level
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