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Add To Calendar 24/02/2016 11:45:0024/02/2016 12:05:00America/ChicagoAquaculture 2016INCLUSION OF YEAST WITH/WITHOUT PREBIOTICS IN RAINBOW TROUT (Oncorhynchus mykiss) DIET: PARTICULAR ATTENTION ON 16S rRNA ANALYSIS Champagne 3The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY


Omolola C. Betiku*, T. Gibson Gaylord, Glenn C. Duff, Carl J. Yeoman and Wendy M. Sealey
 USFWS, Bozeman Fish Technology Center
 4050 Bridger Canyon Road
 Bozeman, MT 59715

Grain Distillers Dried Yeast (GDDY) is a single-cell protein and a by-product of biofuel ethanol production that has previously been investigated as an alternative protein ingredient in rainbow trout nutrition wherein inclusion level greater than 16% diminished growth efficiency. Inclusion of prebiotics: mannan-oligosaccharides (MOS) and Grobiotic-A (GroA) have been reported to improve health and growth performance in rainbow trout fed some alternative proteins.  However, information on the efficacy of these prebiotics in trout consuming GDDY or their impact on the gastrointestinal tract (GIT) microbial composition in rainbow trout is lacking. Hence, this study investigated the effect of inclusion of MOS and GroA prebiotics in GDDY protein replacement diets fed to rainbow trout on performance and GIT microbial composition.

Four equal digestible protein (40% DP) and iso-lipidic (20%) experimental diets: A (100% fishmeal), B (26.5% GDDY), C (26.5% GDDY + 1% MOS), D (26.5% GDDY + 1% GroA) were formulated. Fish with average initial weight of 16.0 ± 0.4 g were stocked at a rate of 20 fish per 400 L tank and three tanks per diet. Fish were fed to apparent satiation twice daily for 12-week. Fish weight and feed intake were determined monthly. At 12 weeks post-feeding, three fish were sampled for body indices and proximate composition. The GIT of three fish were sampled for histology and the GIT microbiota of three additional fish were sampled and analyzed by 16S rRNA gene sequencing.

Contrary to earlier reports, high dietary GDDY inclusion (26.5% inclusion) did not significantly reduce rainbow trout growth but did significantly increase feed intake (p<0.0001) and feed conversion ratio (FCR) (p<0.0001) as was previously observed. Moderate increases in gastrointestinal inflammation also were observed with high GDDY inclusion in the current study. Microbial abundance and diversity changed with GDDY and prebiotics inclusion (Figure 1); dominant phyla were Firmicutes and Ascomycota in trout fed the prebiotics diets while fish fed the GDDY free diet predominantly had Proteobacteria and Cyanobacteria [Note: Cyanobacteria are Autotrophs and not likely to truly colonize the gut, this is more likely to be either chloroplast from ingested plant material or a taxa known as Melainabacteria (]. This study provides insight into the mechanism by which alternate proteins alter microbial gastrointestinal communities in rainbow trout.

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