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Effects of feeding yeasts on blood physiology and gut microbiota of rainbow trout

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]

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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:
LanguageAbstract
Swedish

Jäst utgör ett hållbart proteinalternativ till fiskmjöl i foder till odlad fisk, men resultat
presenterade i denna avhandling indikerar att inblandning med mer än 40% minskar
fisktillväxten. Syftet med denna avhandling var att förstå effekten av högre halter av
inaktiverad respektive levande jäst till fisk utan negativa hälsoeffekter. Specifikt
effekterna på röda blodkroppar, upptag av plasmaaminosyror, tarmmikrobiota och
stress/immunsvar på regnbåge (Oncorhynchus mykiss).

Postprandiala blodprover togs från dorsal aorta-kannulerad regnbåge som utfodrats
med dieter där 60% av fiskmjölsproteinet ersatts med två olika typer av
inaktiverat/avdödad jäst, Saccharomyces cerevisiae och Wickerhamomyces anomalus,
gjord av värmextrudering. Blodanalys visade högre blod-pH och hemoglobinnivåer
vilket associeras med jästens lägre buffertkapacitet och eventuell hemolytisk anemi på
grund av ökad nukleinsyrametabolism. Plasmaanalyser visade att aminosyrornas upptag
var lika mellan fisk som matades med jäst eller fiskmjöl, förutom att koncentration av
plasma-metionin var högre hos fiskar som utfodrats med jäst-diet. I en senare studie
utfodrades regnbåge med levande jäst (S. cerevisiae) vid två olika temperaturer (11 och
18°C). Inga biverkningar på blodfysiologi hittades, även om de flesta celler överlevde
och inte metaboliserades i tarmkanalen. Dessa resultat indikerar att minskad fisktillväxt
inte enbart kan bero på lägre aminosyrokoncentration, utan snarare en för hög
nukleinsyrahalt i fodret men bara när jäst metaboliserades.

I ytterligare två studier studerades tillväxt och tarmbiota där fisk gavs foder med
inaktiverad jäst som ersatte 20, 40 och 60% av fiskmjölprotein därefter utfördes försök
med fisk som utfodrades vid 11 och 18°C med 40% inbladning av levande jäst i fodret.
Hög genomströmnings sekvensering av distala tarmen avslöjade att inaktiverad W.
anomalus påverkade både antal och diversitet av bakterier i tarmen medan både
inaktiverad och levande S. cerevisiae hade mindre effekt. Ökad vattentemperatur
minskade mängden mjölksyrabakterier och minskad bakteriell mångfald i tarmen. I
båda studierna har Debaryomyces hansenii, S. cerevisiae och Rhodotorula spp.
påträffade i fisktarmen medan fisk som utfodrats med levande jäst, bidrog till en ökad,
jästbelastning i tarmen. Fisken vid 18°C hade dock högre plasmakortisolnivåer och
reducerat genuttryck av proinflammatoriska cytokiner vilket var än mer påtagligt hos
fisk utfodrade med levande jäst. Dessa resultat tyder på att ökad temperatur utsätter fisk
för kronisk stress och att utfodring av levande jäst påverkar immunresponsen.
Fisktillväxt och välfärd bibehållas genom att ge jäst i kallt vatten med lägre
nukleinsyrahalt och om det lyckas kan det leda till högre ersättning av fiskmjöl.

Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :August 2017
Depositing date:August 2017
Volume:2017:69
Number of Pages:76
Papers/manuscripts:
NumberReferences
IHuyben, D., Vidaković, A., Nyman, A., Langeland, M., Lundh, T.* & Kiessling, A. (2017). Effects of dietary yeast inclusion and acute stress on post-prandial whole blood profiles of dorsal aorta-cannulated rainbow trout. Fish Physiology and Biochemistry 43(2), 421-434.
IIHuyben, D., Vidaković, A., Nyman, A., Langeland, M., Lundh, T.* & Kiessling, A. (2017). Effects of dietary yeast inclusion and acute stress on postprandial plasma free amino acid profiles of dorsal aortaǦcannulated rainbow trout. Aquaculture Nutrition 1-11, DOI: 10.1111/anu.12551.
IIIHuyben, D.,*, Nyman, A., Vidaković, A., Passoth, V., Moccia, R., Lundth, T., Kiessling, A., Dicksved, J. & . (2017). Effects of dietary inclusion of the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus on gut microbiota of rainbow trout. Aquaculture 473, 528-537.
IVHuyben, D.*, Sun, L., Moccia, R., Kiessling, A., Dicksved, J. & Lundh, T. Gut microbiota of rainbow trout is affected by high dietary inclusion of live yeast and increased water temperature. (Manuscript).
VHuyben, D., Vidaković, A., Sundh, H., Sundell,. Kiessling, A. &� Lundh, T. Blood and intestinal physiology of rainbow trout is affected by high dietary inclusion of live yeast and increased water temperature. (Manuscript)
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:03 Sep 2017 14:56
Project info:
Name:Fish REaring and Stress Hazards
Acronym:FRESH
ID:223-2013-297
Programme:Animal Welfare and Animal Welfare-enhancing Measures

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