Prebiotics in Aquaculture: New Strategy for Larviculture Improvment?

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1 Prebiotics in Aquaculture: New Strategy for Larviculture Improvment Mahious A.S. LARVI 05 Fish & Shellfish Larviculture Symposium September , Belgium

2 General concept Probiotics Synbiotics Prebiotics Living bacteria in the diet Oligofructose or inulin in the diet Stomach % survival Small intestine Adhesion Activity Active exogenous bacteria Colon Stimulation of active endogenous beneficial bacteria Total transfer to the colon Delzenne & Roberfroid, 1994

3 Why use prebiotics in aquaculture Exogenous probiotics => Adherence Activity Lactic acid bacteria (LAB) are part of the natural intestinal microflora of healthy fish (Ringo & Gatesoupe, 1998) LAB have probiotic properties Prebiotics stimulate growth and activity of probiotic bacteria (LAB) resident in the gut Prebiotics => food ingredients => Easier to apply in dried feed (stable after feed processing and during storage)

4 Definition of a prebiotic Gibson al., 2004 Prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon. There are 3 criteria to be classified as a preboiotic: Resistance to gastric acidity, hydrolysis by digestive enzymes and gastrointestinal absorption Fermentation by intestinal flora Selective stimulation of the growth and/or the activity of intestinal bacteria associated with health

5 Prebiotics classification Gibson et al., 2004 Candidates Criterion 1 Criterion 2 Criterion 3 Prebiotic Inulin, Oligofructose Yes Transgalacto-oligosaccharides (+) + + Yes Lactulose (+) + + Yes Isomalto-oligosaccharides Lactosucrose Xylo-oligosaccharides Soybean oligosaccharides

6 Inulin and oligofructose from chicory, Cichorium Intybus INULIN SOURCE (by water extraction) 75% water 17% inulin 8% others SALAD «WITLOOF» «BELGIAN ENDIVES» (2nd growth in the dark) COFFEE SUBSTITUTE (by roasting)

7 Chemical structure of inulin and oligofructose Extraction Inulin Partial hydrolysis Oligofructose (hot water) (enzymatic) GF n GF n and F n Chicory roots > T/year 15-17% inulin DP = 3-60 ß(2-1) DP = 2-8 ß(2-1) Glucose Fructose Reducing fructose DP = Degree of Polymerisation

8 Inulin or oligofructose in diet Inulin and oligofructose activity (Van Loo, 2004) + Bifidobacteria, Lactobacillus Short chain fatty acid (acetate, butyrate, propionate) ph, mineral absorption Mucosal cell proliferation Immunomodulators anticarcinogen harmfull bacteria

9 Application of inulin and oligofructose to fish nutrition Turbot, Psetta maxima Siberian sturgeon, Acipencer baeri African catfish, Clarias gariepinus

10 Turbot, Psetta maxima (Mahious et al.,2005) Experiment 1: Early larval stage Artemia enriched with inulin or oligofructose Experiment 2: Weaning stage Inert feed supplemented with inulin or oligofructose

11 Turbot, Psetta maxima (Mahious et al.,2005) Experiment 1: Early larval stage Artemia enriched with inulin or oligofructose Experiment 2: Weaning stage Inert feed supplemented with inulin or oligofructose

12 Experiment 2: Weaning stage Start End 3 dph 7dph 29 dph 39 dph 55 dph Rotifers Artemia nauplii Artemia + Inert diet Inert diet Brachionus Artemia 2% Cellulose (control), 2% Raftiline ST (inulin) or 2% Raftilose P95 (oligofructose)

13 Growth of turbot larvae weaned with inulin and oligofructose 0,6 0,5 b (P<0,01) a a Final weight (g) 0,4 0,3 0,2 0,1 0,0 Control Inulin Oligofructose

14 Intestinal flora of turbot larvae weaned with inulin and oligofructose Control 36% 28% 36% Inulin Oligofructose 34% 22% 42% 16% 44% Vibrio sp. S % Vibrio sp. L2C55 14% Other Vibrio spp. Other bacteria Bacillus sp. L171P95 3%

15 Specific growth rate (SGR % day -1 ) of fish fed prebiotics 0,93 0,92 0,91 0,9 0,89 0,88 0,87 4,2 4,1 4 3,9 3,8 3,7 3,6 3,5 3,4 3,3 Siberian sturgeon, Acipenser baeri African catfish, Clarias gariepinus Control Inulin Oligofructose

16 In vitro short chain fatty (SCFA) production with the content of spiral valve of Siberian sturgeon % % 5 60% % % 0 Total SCFA (mmol/g) Lactate (mmol/g) 0% Control Inulin Ologofructose Control Acetate Inulin Propionate Oligofructose Butyrate

17 Bacterial flora of Siberian sturgeon and African catfish under study Culturable flora => description of microbial biodiversity in the gut (GTG)5-PCR: clustering and selection Partial 16S sequencing API, FAME Non-culturable flora => microbial composition of fish fed prebiotics Bacterial DNA extraction from gut mucus DGGE: needs to be further improved Results coming

18 Conclusions Introduction of prebiotics in inert feed is easy Oligofructose improves growth in turbot larvae at weaning Emergence of probiotic bacteria in the gut of turbot weaned with prebiotics Inulin and oligofructose improve growth of Siberian sturgeon and African catfish Production of organic acids = indication of specific flora that use inulin and oligofructose as substrate Impact of prebiotic needs to be tested in several fish species and on long term feeding period

19 Is it possible to control bacterial flora by using pro-, pre- and symbiotics at feeding stages Probiotics Symbiotics Prebiotics Larvae Weaning Juveniles, adult Isolation of probiotic strains