DESIGNING WEANING DIETS BASED ON THE ONTOGENY OF DIGESTIVE TRACT ENZYME ACTIVITY DURING THE CARNIVOROUS-OMNIVOROUS TRANSITION IN GREY MULLET (MUGIL CEPHALUS) JUVENILES B. Koven 1*, E. Gisert 2, O. Nixon 1, I. Meiri-Ashkenzi 1, A. Gon 1, M.M. Solovyev 3,4, A. Tndler 1, H. Rosenfeld 1
Bckground Grey mullet lrve strict crnivores feeding on zooplnkton. After metmorphosis chnge to herivorous/omnivorous diet-serching for less sline esturies with higher primry productivity of micro nd mcrolge. Erlier study investigted the effect of greening tnks with different concentrtions of Isochrysis nd Nnnochloropsis during lrvl rering on DT enzyme ontogeny in 25, 40, 61 nd 79 dph juveniles. No cler effect of lge ddition ws oserved on enzyme ontogeny ut the DT enzyme ontogeny with ge ws reveled.
mylse (U/mg) lkline phosphtse (U/mg prot) lkline P/leu-l rtio Erlier study 250 200 150 100 50 0 c c c 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 C IA IB NA NB Tretments nd ge (dph) 10 8 6 4 2 0 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 18 25 40 61 79 C IA IB NA NB Tretments nd ge (dph) 600 400 200 0 c 18 40 18 40 18 40 18 40 C IA IB NA NB 18 25 40 61 79 25 61 79 25 61 79 25 61 79 25 61 79 Tretments nd ge (dph) c Amylse ctivity stedily incresed to pek t 79 dph. signling herivorous/detritivorous feeding, lkline phosphtse (mrker for BBM development) peked from 61 to 79 dph. the AP/leu-l rtio (indictor of gut mturtion) peked t 61 dph ut then declined in 79 dph.
Bckground IOLR wening protocol- mullet juveniles cn e wened off live Artemi to dry, prepred diet from 24-37 dph. Results from the erlier study indicted this wening period overlps trophic shift from crnivory to more crohydrte rich diet. Question: Should the wening diet stisfy crnivorous, omnivorous or herivorous mode of feeding?
Aim Evlute the effect of feeding crnivorous, herivorous or omnivorous wening diet to juvenile mullet on; () growth, survivl nd popultion weight distriution () the ontogeny of pncretic, rush order nd cytosolic enzyme ctivity.
Experimentl design Fifteen 17 l quri in flow through system with 40, UV treted temperture (24.5 ⁰ C) controlled sewter were stocked with eighty-five 23 dph lrve qurium -1. Tested three wening dietry tretments, differing in their protein nd crohydrte content, in replictes of 5 quri tretment -1. Diet 1 dried Ulv lctuc (35% plnt protein, 56% crohydrte), Diet 2 commercil strter diet cvir (Bernqu, Belgium; 55% niml protein, 8% crohydrte) Diet 3 1:1 w/w mixture of diets 1 nd 2. Dph Rotifers Artemi Dietry tretments Size (µm) Nnnochloropsis ocult 23 x2 dy x2 dy 0-4x10 6 cells\ml 24-25 x2 dy x2 dy X1 50-100 4x10 6 cells\ml 26-33 0 x2 dy x2 dy 100-200 4x10 6 cells\ml 34-37 0 x2 dy x3 dy 200-300 0 38-53 0 0 x5 dy 200-500 0
Avg length (cm) Avg fish DW(mg) Effect of the Cvir, Ulv nd Cvir: Ulv on () 53 dph fish length nd () dry weight (DW) t the end of the experiment. 3.0 2.5 2.0 1.5 1.0 () 300 250 200 150 100 () c 0.5 50 0.0 Cvir Cvir:Ulv Ulv Tretments 0 Cvir Cvir:Ulv Ulv Tretments
Biomss (g) Percent (%) of popultion Effect of diets on iomss nd weight distriution 15.0 80 12.5 10.0 7.5 5.0 2.5 0.0 Cvir Cvir: Ullv Ulv Tretments 60 40 20 0 Cvir Cvir:ulv Ulv <100 100-200 200-300 300-400 400-500 >500 Weight distriution (mg)
trypsin (U/mg prot) lipse (U/mg prot) mylse (U/mg prot) lkline protese (U/mg prot) chymotrypsin (U/mg prot) Pncretic enzymes mylse lkline protese chymotrypsin 0.6 0.4 0.2 0.10 0.08 0.06 0.04 0.02 0.08 0.06 0.04 0.02 0.0 cvir ulv:cvir ulv 0.00 cvir ulv:cvir ulv 0.00 cvir ulv:cvir ulv Tretments Tretments Tretments trypsin lipse 0.015 0.04 0.010 0.03 0.02 0.005 0.01 0.000 cvir ulv:cvir ulv 0.00 cvir ulv:cvir ulv Tretments Tretments
Intestinl mturtion index (AP/LAP) mltse (U/mg prot) lkline phosphtse (U/mg prot) leucine mino peptidse (U/mg prot) 0.008 0.006 0.004 0.002 lkline phosphtse (AP) Brush order nd cytosolic enzymes 0.006 0.004 0.002 leucine minopeptidse (AN) 0.000 0.00005 0.00004 0.00003 0.00002 cvir ulv:cvir ulv Tretments Intestinl mturtion index 0.000 60 40 20 cvir ulv:cvir ulv Tretments Mltse 0.00001 0.00000 cvir ulv:cvir ulv Tretments 0 cvir ulv:cvir ulv Tretments
Summry Fish fed the cvir:ulv diet grew est (length, dry weight, tnk iomss)- not strict herivore t this stge. Fish fed Ulv resulted in significntly higher numers of smller fish (<100 mg) nd lower numers of lrger fish (200-400 mg). Fish fed cvir nd cvir:ulv resulted in significntly lrger fish (300-400 mg) Incresing dietry cho:pro rtio significntly incresed pncretic mylse, protese nd trypsin. Chymotrypsin nd lipse independent of cho:pro rtio. BBM enzymes lkline phosphtse nd leucine minopeptidse incresed nutrient sorption nd mturtion with higher dietry ccessile protein in nutrient dense diet. Decresing AP/LAP (leucine lnine peptidse) with incresing CHO suggests gut mturtion decreses with more ulv in diet.
Conclusions Enzyme specific ctivity ffected y feed composition. Most effective diet ws omnivorous sed, in terms of DW, length, tnk iomss, size distriution nd enzyme cpility.
Recommendtion Recommend n omnivorous wening diet (c 45% protein, 32% crohydrte) during this stge of development in juvenile grey mullet. Tke home Optimum diet -considerle levels of protein for growth nd strch to provide glucose for energy to spre protein from ctolism nd direct it towrd growth. Mimic nturl omnivorous diet of mullet in esturies.
Thnk you