Skip to main content
SLU:s publikationsdatabas (SLUpub)

Sammanfattning

The growing demand for sustainable aquaculture has intensified the need for alternative protein sources that can consistently replace fish meal in salmonid diets. Many current alternatives, particularly plant-based proteins, compete directly with human food resources. Microbial ingredients present a promising solution because they can valorize low-value substrates while providing high-quality nutrients. Although bacterial meals and single-cell fungi have been studied extensively, the use of filamentous fungi as feed ingredients for salmonids remains comparatively underexplored.

This licentiate thesis investigates the potential of several filamentous fungi, cultivated on industrial and forestry by-products, as feed ingredients for rainbow trout. Key nutritional and functional aspects were evaluated, including digestibility, effects on growth performance and gut health, and physical pellet quality. In Paper 1, four filamentous fungi namely, Aspergillus oryzae, Rhizopus oligosporus, Rhizopus delemar, and Paecilomyces variotii, were assessed for their chemical composition, amino acid indices, and digestibility. Their influence on pellet quality was also examined. Among these, P. variotii showed the most favourable characteristics and was selected for further evaluation in a growth trial using graded inclusion levels.

In Paper 2, a nine-week growth trial was conducted with diets containing 0% (control), 5%, 10%, 20%, and 30% P. variotii. Growth performance, feed utilization, gut health parameters, and technical feed quality were assessed. The results showed no reduction in growth performance compared with the control up to a 20% inclusion level, while performance declined at 30%. Notably, villus length was significantly higher in fish fed the 30% inclusion diet.

In conclusion, P. variotii was found to be the most suitable microbial ingredient among the tested ingredients and hence was chosen for further analysis. P. variotii up to 20% inclusion levels did not have any effects on the growth. Further studies with longer feeding periods are required to further judge the efficacy of P. variotii as a suitable microbial ingredient for rainbow trout.

Nyckelord

Rainbow trout; Filamentous fungi; growth performance; gut health; technical pellet quality

Publicerad i

Utgivare: Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences

SLU författare

UKÄ forskningsämne

Mikrobiologi
Fisk- och akvakulturforskning

Publikationens identifierare

  • ISBN: 978-91-8124-153-2
  • eISBN: 978-91-8124-154-9

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/145107