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A test of "nutritional wisdom" in perch ( Perca fluviatilis) by self-selection of encapsulated macronutrients

By E. Brannas, A. Strand

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Abstract

Developing optimal diets based on fish macronutrient requirements is an expensive and laborious task requiring years of research. However, many species of fish can compose a species-specific optimal diet from single source macronutrients in capsules through self-selection. Eurasian perch is a species in which commercial culture is still in development and determination of whether this species can self-select its own diet is still unknown. Twenty-four individually held Eurasian perch ( Perca fluviatilis) were trained to eat capsules of three different colours (purple, yellow and white) filled with a commercial diet. The fish exhibited a pronounced preference for the purple capsules. After training, capsules of each colour were then filled with either of three pure macronutrients to subvert the colour bias. There was still a preference of purple capsules which decreased with time. The resulting self-selection of macronutrients showed a significant lower selection of capsules with carbohydrates (17%) but no significant difference between fat (45%) and protein (38%). This self-selected proportion of macronutrients deviates from the recommended diet for farmed perch; 62% protein, 26% carbohydrates and 12% fat. The self-selected mean energy level with commercial feed in the capsules (133.010.6 kJ kg BW -1 day -1) filled with the commercial diet was significantly lower than when the capsules were filled with macronutrients (197.024.1 kJ kg BW -1 day -1). The perch actively selected against carbohydrates and reduced the number of capsules eaten when offered macronutrients, although not sufficient to keep daily energy intake at a constant level compared to the commercial diet. This result together with the preference for a specific colour implies that self-selection of diet composition may not be a suitable tool for the feed optimization of perch.

Publication Title Applied Animal Behaviour Science
Volume 171
Pages 219-225
ISBN/ISSN 0168-1591
DOI 10.1016/j.applanim.2015.08.009
Language English
Author Address Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Science, SE-901 83 Umea, Sweden.eva.brannas@slu.se asa.strand@bioenv.gu.se
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Tags
  1. Analysis
  2. Animal behavior
  3. Animals
  4. Aquacultural and fisheries
  5. Aquatic organisms
  6. Carbohydrates
  7. Diets
  8. Energy
  9. Estimation
  10. Feeds
  11. Fish
  12. nutrients
  13. optimization
  14. peer-reviewed
  15. Research
  16. training
  17. vertebrates
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  1. peer-reviewed