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Castro V.,Nofima As | Castro V.,Norwegian University of Life Sciences | Castro V.,AVS Chile S.A. | Grisdale-Helland B.,Nofima As | And 11 more authors.
BMC Physiology | Year: 2013

Background: Like humans, fish can be classified according to their athletic performance. Sustained exercise training of fish can improve growth and physical capacity, and recent results have documented improved disease resistance in exercised Atlantic salmon. In this study we investigated the effects of inherent swimming performance and exercise training on disease resistance in Atlantic salmon.Atlantic salmon were first classified as either poor or good according to their swimming performance in a screening test and then exercise trained for 10 weeks using one of two constant-velocity or two interval-velocity training regimes for comparison against control trained fish (low speed continuously). Disease resistance was assessed by a viral disease challenge test (infectious pancreatic necrosis) and gene expression analyses of the host response in selected organs. Results: An inherently good swimming performance was associated with improved disease resistance, as good swimmers showed significantly better survival compared to poor swimmers in the viral challenge test. Differences in mortalities between poor and good swimmers were correlated with cardiac mRNA expression of virus responsive genes reflecting the infection status. Although not significant, fish trained at constant-velocity showed a trend towards higher survival than fish trained at either short or long intervals. Finally, only constant training at high intensity had a significant positive effect on fish growth compared to control trained fish. Conclusions: This is the first evidence suggesting that inherent swimming performance is associated with disease resistance in fish. © 2013 Castro et al.; licensee BioMed Central Ltd.

Sorensen M.,CoE As | Sorensen M.,Norwegian University of Life Sciences | Nguyen G.,Norwegian University of Life Sciences | Nguyen G.,Research Institute for Aquaculture | And 4 more authors.
Aquaculture Research | Year: 2010

This experiment investigated the physical qualities ('Holmen' durability; 'tumbling box' durability; and pellet strength, length and diameter) of extruded fishmeal-based feeds produced using different starch sources, screw configurations, with or without steam injected in the barrel. The starch sources tested were native or pre-gelatinized potato starch (PGS), wheat starch (WS), whole wheat (WW) or a combination of WS and WW. Screw configurations were a polygon element, followed by two left-pitched segments, Polygon_2L; a polygon, followed by one left-pitched and one right-pitched element, Polygon_LR; and no polygon section, alternating left- and right-pitched elements, LRLR. Starch source and screw configuration affected the physical quality the most. Pellets produced with LRLR had the highest 'Holmen' durability (76%), hardness (30 N) and the least diameter (5.3 mm). The lowest durability (37%) and hardness (22 N) were obtained with Polygon_LR. Potato starch yielded higher expansion than cereal starch. The highest 'Holmen' durability was seen for PGS (79%), while WS yielded the lowest value (44%). Injection of steam reduced hardness and 'Holmen' durability, but provided a minor overall contribution to physical quality compared with the starch source and screw configuration. 'Holmen' durability appeared to be suitable to unveil variation (37-79%) in physical quality, while 'Tumbling box' durability (98.4-98.8%) did not prove efficient. © 2009 The Authors. Journal Compilation © 2009 Blackwell Publishing Ltd.

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