Huyben, David
(2017).
Effects of feeding yeasts on blood physiology and gut microbiota of rainbow trout.
Diss. (sammanfattning/summary)
Uppsala :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae, 1652-6880
; 2017:69
ISBN 978-91-7760-028-2
eISBN 978-91-7760-029-9
[Doctoral thesis]
![]() |
PDF
1MB |
Abstract
Yeast represents a sustainable protein alternative to fishmeal in diets for farmed fish, although more than 40% replacement has been shown to reduce fish growth and welfare. This thesis investigated the effects of feeding high inclusions of inactivated and live yeasts to fish in order to replace fishmeal without negative health consequences. The specific focus was on red blood cell characteristics, plasma amino acid uptake, gut microbial communities and stress/immune responses of rainbow trout (Oncorhynchus mykiss).
Post-prandial blood samples were collected from dorsal aorta-cannulated rainbow trout fed diets in which 60% fishmeal protein was replaced with two yeast species, Saccharomyces cerevisiae and Wickerhamomyces anomalus, inactivated by heat extrusion. Blood analysis showed that feeding both yeasts resulted in higher blood pH and haemoglobin levels, which were associated with lower buffering capacity of yeast and possible haemolytic anaemia from metabolism of high levels of nucleic acid. Plasma analysis revealed that amino acid uptake was similar in fish fed both yeasts and fishmeal, except for higher methionine in fish fed yeasts attributed to higher supplementation. In a later study, fish were fed live S. cerevisiae and reared at 11 and 18°C. No adverse effects on blood physiology were found, although most cells survived digestion and were not metabolised. These results indicate that reduced growth in fish fed yeast may not be due to lower amino acid content, but rather to metabolism of high levels of nucleic acid leading to impaired red blood cell function.
In separate studies, fish were fed inactivated yeasts that replaced 20, 40 and 60% of fishmeal protein and fish kept at 11 and 18°C were fed 40% replacement with live yeast. High-throughput sequencing of the distal gut revealed that inactivated W. anomalus affected bacterial diversity and abundance, while both inactivated and live S. cerevisiae had minor effects. Increased temperature reduced the abundance of lactic acid bacteria and reduced bacterial diversity. In both studies, Debaryomyces hansenii, S. cerevisiae and Rhodotorula spp. were naturally present in the fish gut and feeding live yeast, but not inactivated, increased the gut yeast load. Fish at 18°C had higher plasma cortisol levels and suppressed expression of inflammatory cytokines, which were further suppressed when fed live yeast. This suggests that increased temperature subjected fish to chronic stress and that feeding live yeast may impair the innate immune response. In conclusion, this thesis suggest that impaired red blood cell and immune function are key factors reducing growth and welfare of rainbow trout fed yeast and managing these factors may enable sustainable replacement of fishmeal.
Authors/Creators: | Huyben, David | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Title: | Effects of feeding yeasts on blood physiology and gut microbiota of rainbow trout | ||||||||||||
Alternative abstract: |
| ||||||||||||
Series Name/Journal: | Acta Universitatis Agriculturae Sueciae | ||||||||||||
Year of publishing : | August 2017 | ||||||||||||
Depositing date: | August 2017 | ||||||||||||
Number: | 2017:69 | ||||||||||||
Number of Pages: | 76 | ||||||||||||
Papers/manuscripts: |
| ||||||||||||
Place of Publication: | Uppsala | ||||||||||||
Publisher: | Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences | ||||||||||||
ISBN for printed version: | 978-91-7760-028-2 | ||||||||||||
ISBN for electronic version: | 978-91-7760-029-9 | ||||||||||||
ISSN: | 1652-6880 | ||||||||||||
Language: | English | ||||||||||||
Publication Type: | Doctoral thesis | ||||||||||||
Full Text Status: | Public | ||||||||||||
Agris subject categories.: | L Animal production > L51 Animal physiology - Nutrition M Aquatic sciences and fisheries > M12 Aquaculture production | ||||||||||||
Subjects: | (A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Microbiology (Microbiology in the medical area to be 30109) (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Fish and Aquacultural Science | ||||||||||||
Agrovoc terms: | trout, oncorhynchus mykiss, feeds, sustainable aquaculture, animal welfare | ||||||||||||
Keywords: | aquaculture, rainbow trout, yeast, gut microbiota, blood physiology, stress response, immune response, alternative protein, fishmeal | ||||||||||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-4291 | ||||||||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4291 | ||||||||||||
ID Code: | 14478 | ||||||||||||
Faculty: | VH - Faculty of Veterinary Medicine and Animal Science | ||||||||||||
Department: | (VH) > Dept. of Animal Nutrition and Management | ||||||||||||
External funders: | FORMAS | ||||||||||||
Deposited By: | David Huyben | ||||||||||||
Deposited On: | 16 Aug 2017 07:37 | ||||||||||||
Metadata Last Modified: | 10 Sep 2020 13:41 | ||||||||||||
Project info: | |||||||||||||
Name: | Fish REaring and Stress Hazards | ||||||||||||
Acronym: | FRESH | ||||||||||||
ID: | 223-2013-297 | ||||||||||||
Programme: | Animal Welfare and Animal Welfare-enhancing Measures |
Repository Staff Only: item control page