114 research outputs found
Økologisk yngelfoder til regnbueørred - et sundere alternativ for fisken?
Regnbueørreden er den dominerende produktionsfisk i Dansk akvakultur, og der produceres årligt ca. 30.000 tons i ferskvandsopdræt. I de senere år er der igangsat produktion af økologiske fisk og mængden er stigende. I 2013 er der yderligere opstartet produktion af økologisk regnbueørred yngel, og dette medfører nogle ekstra udfordringer i forhold til forebyggelse af sygdomme og behandling. En af betingelserne for at en fisk kan sælges som værende økologisk er, at der er en begrænsning for hvor mange gange den kan behandles med antibiotika i løbet af dens liv, for ellers mister den sin økologiske status. Det er derfor vigtigt at sikre optimale forhold, så fisken undgår at blive syg. I Organic RDD projektet OPTIFISH undersøges det bl.a. hvordan foder indeholdende forskellige typer af olie og protein påvirker fiskeynglens evne til at overleve smitte med to af de bakterier, der hyppigt giver årsag til dødelighed på yngelstadiet; Flavobacterium psychrophilum og Yersinia ruckeri.Dette med henblik på derefter at kunne udpege en fodersammensætning, der kan sikre sundere fiskeyngel, der bedre kan modstå sygdom. Udover at evaluere overlevelsen i forbindelse med smitte, måles effekterne på forskellige immunparametre samt på bakteriefloraen i tarmen også.Forsøg samt resultater og konklusion beskrives
THE INTESTINAL MICROBIOTA IN RAINBOW TROUT (ONCORHYNCHUS MYKISS) IS INFLUENCED BY DIET TYPE AND YERSINIA RUCKERI CHALLENGE
In recent years it has become more and more evident that the bacterial flora in the gut of warm-blooded animals modulates physiological processes and the immunological status of the host. Besides effects on growth parameters, commensal intestinal bacteria balance the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota is also important in lower vertebrates such as fish? Is the microbiota related to the diet type and does it play a protective role in connection to pathogenic challenge? To examine these questions rainbow trout fry were fed two different diets of either a marine or vegetable origin from first feeding and onwards. At a size of about four gram the fish were bath challenged by Yersinia ruckeri serotype O1 and intestines were then sampled 5 days post challenge for subsequent metagenomic examination. Next-generation sequencing was applied for the metagenomic studies using the Illumina HiSeq 2000 platform. The results showed two distinctly different microbial patterns in the intestines dependent on the diet type. Fish fed a marine based diet overall had a significantly higher amount of the class β-proteobacteria, while the amount of reads belonging to phylum Firmicutes were significantly higher in the intestines of vegetable fed fish. The genera within phylum Firmicutes present in significantly higher amounts in vegetable fed fish were Weissella, Leuconostoc and Streptococcus. Genus Aeromonas from the γ-proteobacteria class was also present in significantly higher amounts in the vegetable fed fish. When challenged with Yersinia ruckeri, fish with a high amount of sequence reads belonging to genus Yersinia had a significantly lower amount of reads from the order Burkholderiales relative to non-infected control fish and fish with a low amount of Yersinia specific sequences. Further, these infected fish further clustered separately when analyzing the bacterial community on a PCA plot. The immunological examinations using RT-qPCR showed similar constitutive expression between the two diet groups, but the response differed between the two diet groups in challenged fish. Here, the general pattern was a pro-inflammatory response in the intestine of marine fed fish challenged with Yersinia ruckeri relative to non-infected control fish, while several immune genes were down-regulated in vegetable fed fish relative to non-infected control fish. Overall, the results indicate that the gut microbiota in rainbow trout is highly plastic according to the type of diet and does further seem to be involved in the immunological response in connection to pathogenic challenge
Is the intestinal microbiota in rainbow trout influenced by diet type and challenge by Yersinia ruckeri?
In recent years it has become more and more evident that the bacterial flora in the gut of warm-blooded animals modulates physiological processes and the immunological status of the host. Besides effects on growth parameters, commensal intestinal bacteria balance the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota is also important in lower vertebrates such as fish? And does it play a role in connection to pathogenic challenge? To examine these questions rainbow trout fry were fed two different diets of either a marine or vegetable origin directly after first feeding. At a size of about four gram the fish were bath challenged by Yersinia ruckeri and intestines were then sampled 5 and 18 days post challenge for subsequent metagenomic and immunological examinations. Next-generation sequencing was applied for the metagenomic studies using the Illumina HiSeq platform. The results clearly showed two different microbial patterns in the intestines dependent on the diet type. Control fish fed a marine based diet overall had a higher amount of proteobacteria, while high amount of reads belonging to phylum Firmicutes dominated in the intestines of vegetable fed fish. Several genera within the order Lactobacillales belonged to the many reads from Firmicutes. In challenged fish with a high load of reads from genus Yersinia there was a significantly lower amount of reads from the order Burkholderiales. Further, these fish further clustered separately when analyzing the bacterial community on a PCA plot. The immunological examinations using RT-qPCR showed no different expression patterns between the diet groups in control fish, but the response was very different in connection to challenge. Here, the general pattern was a pro-inflammatory response in the intestine of marine fed fish challenged with Yersinia ruckeri, while several immune genes were down-regulated in vegetable fed fish. Overall, the results indicate that the gut microbiota in rainbow trout is highly plastic according to the type of diet and does further seem to be involved in the immunological response in connection to pathogenic challenge
DIET TYPE AND CHALLENGE BY YERSINIA RUCKERI INFLUENCE THE INTESTINAL MICROBIOTA IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)
In warm-blooded animals such as humans and pigs the intestinal microbial composition is dependent on the type of ingested diet. It is known that it also influences the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota has the same impact in lower vertebrates such as fish?
To examine this rainbow trout fry were fed two different diets of either a marine or vegetable origin. At a size of about four gram a subset of the fish was bath challenged by Yersinia ruckeri serotype O1 and intestines were then sampled 5 days post challenge from challenged fish (n = 40) and non-challenged control fish (n = 40). Subsequent metagenomic examination based on the 16S rDNA gene was then performed using the Illumina HiSeq 2000 platform. Obtained sequences were paired, sorted, filtered, checked for chimeras and finally mapped against the Greengene database using the open-source package Bion-meta. Analysis of the microbial communities when then made for the non-infected control fish and Yersinia ruckeri challenged fish.
For the non-infected control fish, the results showed two distinctly different microbial patterns in the intestines dependent on the administered diet type. Fish fed a marine based diet overall had a significantly higher amount of the class β-proteobacteria, while phylum Firmicutes was significantly higher abundant in the intestines of vegetable fed fish. The genera within phylum Firmicutes present in significantly higher amounts in vegetable fed fish were Weissella, Leuconostoc and Streptococcus. Genus Aeromonas from the γ-proteobacteria class was also present in significantly higher amounts in the vegetable fed fish.
The microbial community was different in the fish that were challenged by Yersinia ruckeri. Challenged fish clustered into two groups according to the load of Yersinia ruckeri specific reads in their intestine; the main part of challenged fish (n = 34) had a low amount of Yersinia specific reads (≤ 1.2 % of total amount of reads), while a minor group (n = 6) had a high load ranging between 13.9 and 23.2 % of all reads. These ‘high Yersinia level’ fish had a significantly lower amount of reads from the order Burkholderiales relative to the ‘low Yersinia level’ fish and non-infected control fish. Further, the ‘high Yersinia level’ fish further clustered separately when analyzing the bacterial community on a PCA plot.
The immunological examinations were performed by RT-qPCR in order to measure the expression of selected immune genes. The results showed a similar expression pattern between the two diet groups of non-infected fish, but the response differed between the two diet groups in challenged fish. Overall, the results indicate that the gut microbiota in rainbow trout, like in warm-blooded animals, is highly plastic according to the type of diet and does also seem to be involved in the immunological response in connection to pathogenic challenge
Infection of Atlantic salmon (Salmo salar) by Moritella viscosa induces quality related markers in the musculature
Foder til økologisk regnbueørre-yngel
Kan vi forbedre sundheden hos ørredyngel ved en optimal fodersammensætning
Økologisk regnbueørred - hvordan påvirker fodersammensætningen fiskenes sundhed?
Regnbueørred er den dominerende produktionsfisk i Dansk akvakultur, og der produceres årligt ca. 30.000 tons i ferskvandsopdræt. I de senere år er der igangsat produktion af økologiske fisk og mængden er stigende. I produktionen af økologiske regnbueørreder i akvakultur er der en øvre begrænsning på to behandlinger med antibiotika i tilfælde af sygdomsudbrud – hvis flere er nødvendige, kan fisken ikke længere sælges som værende økologisk. Derfor er der udfordringer i at undgå, at fiskene bliver syge, bl.a. ved at sørge for, at de får optimalt foder, som styrker deres immunforsvar og dermed evne til at modstå sygdom. Dette undersøges nu nørmere i Organic RDD projektet, OPTIFISH
The gut microbiota in rainbow trout changes after first feeding and is dependent on the type of diet
Influence of organic diets and probiotics on an experimental Flavobacterium psychrophilum infection in rainbow trout fry
Extended abstract published from the conference Flavobacterium 2012.
The aim of the Danish project OPTIFISH is to optimize growth and survival for organic cultured rainbow trout. OPTIFISH investigates how organic vs. non-organic diet types as well as diets with or without probiotics affect the intestine, the intestinal microbiota and survival rates of rainbow trout following exposure to pathogens. The project consists of several work packages, among them the backbone of the project, namely the feed experiments with fry as well as sampling from the different diet groups. The samples will be used for studies of the bacterial microbiota in the fish by e.g. traditional bacteriology and molecular methods (16S rRNA PCR combined with next generation sequencing) as well as for the immunological investigation of the intestine by gene expression studies by quantitative RT-PCR. Fish health will be investigated by experimental exposure of fry to pathogens, e.g. F.psychrophilum.
In the current experiment four diet types were tested on fry, a conventional type (Inicio®, BioMar A/S) with and without probiotics, as well as an organic type with and without probiotic. Bactocell® (Lallemand) was used as the probiotic
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