september | october 2013 -international aquafeed. full edition

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1/68

The potential of

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Understanding ammonia

in aquaculture ponds

Volume 16 I s sue 5 2013 - s ePTemBeR | oCToBeR

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EXPERT TOPIC Salmon

AquaNor event review


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An internAtionAl mAgAzine for the AquAculture feed

industry - incorPorAting fish fArming technologyCONTENTS

AQUA

I n t e r n a t I o n a l

FEED

Volume 16 / Issue 5 / September-October 2013 / Copyright Perendale Publishers Ltd 2013 / All rights reserved

International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom.

All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept

no liability for any errors or omissions or for the consequences of action taken on the basis of information published. Copyright 2013

Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior

permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

Aqua News

3 Newprawnfeedadditivelacksrelianceonfishmeal

3 Aquacultureindustrymaybenefitfromwatermoldgenomestudy

4 Feedsafetyandresponsibilityassurance

5 InternationalCopperAssociationlaunchesnewaquacultureweblibrary

7 Anewaquaculturerevolution?

8 Veggiedietsforcobia

9 TheaquaculturefutureisbrightinIndiana,USA

Features10 Grindingequipmentforaquaticfeedpellets

14 Thepotentialofmicroalgaemealsincompoundfeedsforaquaculture

18 Marinealgalpolysaccharides:anewoptionforimmunestimulation

22 Understandingammoniainaquacultureponds

26 FeedinglinedseahorsejuvenileswithenrichedArtemianauplii

Regular items

5 THEAQUACULTURISTS

32 PHOTOSHOOT38 EXPERTTOPIC-SALMON

45 INDUSTRYEVENTS

HighValueFinfishSymposium

PositioningforprofitatAPA

InternationalAquafeedpublishertoopenmajorfishfeedsymposium

AquaNor2013EventReview

60 CLASSIFIEDADVERTS

62 THEAQUAFEEDINTERVIEW

64 INDUSTRYFACES

www.perendale.co.uk
http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-


4/68

Editor

Professor Simon Davies

Email: [email protected]

Associate Editors

Alice Neal


Professor Krishen Rana


Dr Yu Yu


Editorial Advisory Panel

Abdel-FattahM.El-Sayed(Egypt)

ProfessorAntnioGouveia(Portugal)

ProfessorCharlesBai(Korea)

ColinMair(UK)

DrDanielMerrifield(UK)

DrDominiqueBureau(Canada)

DrElizabethSweetman(Greece)

DrKimJauncey(UK)

EricDeMuylder(Belgium)

DrPedroEncarnao(Singapore)

DrMohammadRHasan(Italy)

Circulation & Events Manager

Tuti Tan


Design & Page Layout

James Taylor


International Marketing Team (UK Office)

Darren Parris


Lee Bastin


Tom Blacker


Richard Sillett


Latin American Office

Ivn MarquettiEmail: [email protected]

Pablo Porcel de Peralta


India Office

Raj Kapoor


More information:

International Aquafeed

7 St George's Terrace, St James' Square

Cheltenham, GL50 3PT, United KingdomTel: +44 1242 267706

Website: www.aquafeed.co.uk

Hello and a warm welcome from Plymouth. In this issue we have a host of informa-

tive articles so I will dive straight in and tell you all about them.

Microalgaehasattractedmuchattentionasapotentialaquafeedingredientsowe

thought wed take a closer look. One of my

ownMSc SustainableAquacultureSystemsstudents,Nathan

Atkinson, weighs up the potential of microalgae meals in

compoundfeedsforaquaculture.

In our interview, Andrew Jackson of IFFO talks about the

strategic use of fishmeal in aquafeeds andhow IFFO helps

ensureresponsiblefishmealproduction.

Theexperttopicthisissueissalmon.Thisspeciesisafavourite

ondinnerplatesacrosstheworldsowelookathowsalmonis

farmedandfedfromIcelandtoTasmaniaandScotlandtoNew

Zealand(andafewotherplacesinbetween).

Turningourattentionawayfromfood,DongZhangandFeiYin

oftheChineseAcademyofFisherySciences,writeabouttheeffectsoffeedinglinedseahorsejuvenileswithenrichedAr temianauplii.

Whilewearetalkingaboutseahorses,our photoshoot this issuealso looksatthis fascinating

creature.MarineConservationCambodiaisdoingsomeveryimportantworkusingaquaculture

tohelprestockthreatenedHippocampus spinosissimusandHippocampus kudapopulationsoffthe

southerncoastofCambodia.Soturntopage32totakealook.

Outsideoftheoffice,thesummerhasbeenfullofeventsandthereareplentymoretolook

forwardtoasweapproachtheautumn.In thisissue,wereviewAquaNorwhichtookplacein

Trondheim,Norway inAugust.Thereview includessomevideointerviewswhichsmartphone

userswillbeabletoaccessinthepalmoftheirhands.Butifyouarenottechnicallysavvy,dont

worry,theresplentyofmaterialtokeepyouoccupied.WealsospoketoAlistairLaneofthe

EuropeanAquacultureSocietywhogaveusthelowdownonAquacultureEurope2013andthe

stateofEuropeanaquaculture.Lookingahead,IameagerlyanticipatingattendingtheBioMarineBusinessConventioninHalifax,

Canada.AfterthesuccessoflastyearsconventioninLondon,Icantwaittofindoutwhatsgoing

oninthisdiversecollectionofindustriesandsamplesomefamousCanadianlobster!

Elsewhere, InternationalAquafeedpublisher, RogerGilbert willbe heading toChinato open

theninthSymposiumof theWorldsChineseScientistsonNutritionandFeedingofFinfishand

Shellfish.Chinaproducesalargeproportionoftheworldsaquaculturesothesymposiumwillbe

goodopportunitytoseethedevelopmentsinaquaticnutritioninthecountry.

Butfornow,IwillleaveyoutothisissueofInternationalAquafeed.Untilnexttime,enjoy!

Professor Simon Davies

CROESO - Welcome

IAF at an industry event near you!It is an exciting time for us here at International

Aquafeed. We are putting together our event schedule for

next year - but in the mean time there are a few big event

announcements that we would like to tell you about.

12 16 November 2013 - Symposium of the Worlds ChineseScientists on Nutrition and Feeding of Finfish and ShellfishRoger Gilbert (publisher of IAF) is making the opening

address of the conference - See more on page 58

17 18 November 2013 - SEAFEX ConferenceRoger Gilbert is the Communications Director and Event Organiser

4 7 February 2014 - 1st Russian Aquaculture Conferenceat Cereals, Mixed Feed

and Veterinary Exhibition

Roger Gilbert is the Organiser and Chairman of the event

24 September 2014 - AQUATECH FEEDTECH at VIV CHINARoger Gilbert is the Organiser and Chairman of the event


5/68

New prawn feed

additive lacks

reliance on fishmeal

Australia's national science

agency, CSIRO, has devel-

oped a new prawn feed

which it claims will help in the

quest for sustainable seafood.

After a decade of research,

the CSIRO scientist s have per-

fected the Novacq prawn feed

additive. Farmed prawns fed with

Novacq grow on average 30

percent faster, are healthier and

can be produced without using

fish products in feeds.

Novacq is an entirely natural

food source based on marine

microbes. CSIRO researchers

have discovered how to feed andharvest the marine microbes, and

convert them into a product that

can then be added to feeds as a

bioactive ingredient.

Including Novacq in the diet of

farmed prawns has shown for the

first time that fish meal and fish

oil can be completely replaced in

the prawn diet, potentially freeing

the prawn aquaculture industr y

from reliance on wild fishery

resources.

CSIRO's Dr Nigel Preston has

been working with the AU$75

million Australian prawn farming

industry for over 25 years, and

says this is a game changer for

the industry.

"We fed Novacq to black tiger

prawns, and it made them even

better for consumers, the envi-

ronment and prawn farmers,"

said Dr Preston.

"This is a major achievement

for the sustainability of Australia's

aquaculture industry as prawns

fed this diet are not only a top

quality product and reach marketsize faster, they also no longer

need to be fed with any products

from wild fishery resources."

"This means that Australian prawn

aquaculture, already a world leader

in sustainability and environmental

management, is now set to become

even better, and really solidifies

aquaculture as a sustainable source

of protein to help meet the ever

growing demand for food."

Until now, Australian prawn

farmers have needed to feed their

prawns with a pellet that includes

some fishmeal or fish oil.

"When we are talking about

relieving pressure on our ocean

stocks of fish, every little bit

helps. Novacq will mean that the

Australian prawn farming industry

could potentially no longer be

reliant on wild-caught fishery

products," said Dr Preston.

Ridley AgriProducts has a

licence to produce and dis-

tribute Novacq in Austral ia and

several Southeast Asian countries.

Bob Harvey, general manageraquafeed, Ridley AgriProducts said

this means the Australian industry

will soon have the opportunity to

use the Novacq feed additive to

boost domestic prawn farm pro-

ductivity.

"We've seen this product in

action and we know how great it is.

We've conducted multiple labora-

tory-based trials, and in conjunction

with CSIRO and a great customer

of ours, Australian Prawn Farms, we

have proven the effects of Novacq

when commercially grown, added

into a commercial prawn feed and

fed to black tiger prawns in multiple

full-scale commercial sized ponds,"

said Harvey.

"Adding Novacq into even the

best performing prawn diets on

the market, we proved a significant

incremental growth rate and food

conversion rate improvement.

We are really excited to now

be able to start the process of

commercialising Novacq, so that

Australian prawn farmers will

soon be able to benefit from it.Over the next twelve months

we will be up scaling production,

performing additional tests and

further farm-scale trials, and then

moving into full-scale commercial

production."

Using technology from theHuman Genome Project

has helped scientists at

Oregon State University, USA to

more clearly identify the genes

used by a type of water mould

that attacks fish and causes millions

of dollars in losses to the aquacul-

ture industry each year.

Research led by Oregon State

University, USA compared the

fish and plant pathogens to clearly

identify the genes involved. By better

understanding how these patho-

gens invade animals, the aquaculture

industry can develop more effective

control methods, such as improved

vaccines and fungicides, researchers

said.

The water mould belongs to a

group of more than 500 species of

fungus-like microorganisms called

oomycetes that reproduce both

sexually and asexually. Oomycetes,

close relatives of seaweeds such

as kelp, are serious pathogens ofsalmon and other fish. This is a partic-

ular problem in regions of the world

where trout and salmon are raised,

including the Pacific Northwest,

Scotland and Chile.

Brett Tyler, professor and directorof the Center for Genome

Research and Biocomputing

at the Oregon State University

College of Agricultural Sciences,

led a project that mapped the

entire genome of an oomycete

species known as Saprolegnia par-

asitica. This is the first time these

methods have been applied

to water mou ld pathogens of

fish.

The pathogen causes a disease

called saprolegniosis, charac-

terized by visible grey or white

patches of mycelium on skin and

fins that can also transfer into the

muscles and blood vessels of fish.

The potato late blight pathogen

that caused the great Irish famine

of the 1840s is a relative ofS. par-

asitica. While saprolegniosis can't

affect humans, relatives of S. par-

asitica can.

"Developing new, environmen-

tally sustainable ways to reduce fishdisease will cut down on the use of

chemicals on fish farms, while also

protecting wild fish, such as salmon,

found in the rivers of the Pacific

Northwest," said Tyler.

Key findings of the research

include:

S. parasitica can rapidly adapt

to its environment through

changes to its genes, allowing it

to spread to new fish species

or overcome fungicides

S. parasitica contains an

enzyme that can actively

suppress a f ish's init ial

immune response, leaving it

less able to defend against

initial stages of infection

Plant pathogens can change

the physiology of their hosts

by using special enzymes

that suppress plant immunity,

while animal oomycetes

have developed different

enzymes, proteins and toxins

that enable infection of fish

S. parasit ica has more

enzymes involved in adap-

tation than humans, allowing

it to recognise and quickly

adapt to a wide variety of

environments

S. parasitica is vulnerable to

an antifungal agent calleda chitin synthesis inhib-

itor, contrary to previous

beliefs that animal-damaging

oomycetes did not contain

any chitin.

Source:

http://

europa.eu

3.1 was the value of

EU aquaculture pro-

duction in 2010

1.26 million

tonnes of aquacul-

ture products were

produced in the EU

in 2010

25% of the seafood

market is supplied

from EU fisheries

15% of the stocks

studied have fishery

improvement

projects (FIPs)

65% comes from

imports

10% comes from EU

aquaculture

13.2 million tonnes

of fishery and aquac-

ulture products were

consumed in the EU

in 2010

3,000 - 4,000

more full-time jobs

could be created

through aquaculture

in the EU

NUMBER CRUNCHINGAquaculture industry may benefit from

water mould genome study

Spmb-Ocob 2013 | InternatIOnal AquAFeed | 3

Aqua News


6/68

Th e r ap id g ro wt h o f

t h e w o r l d p o p u l a -

tion comb ined with the

increasingpurchasepowerofalot

ofpeople arepowerfultriggers

f or t he p r od uc ti on o f a qu a

products.Atthesametime,food

safety and sustainable produc-

tion are essential conditions for

aquaculturetotakeintoaccount.

The GMP+ Feed Certification

scheme offers thepossibility to

provethesafetyandsustainability

ofaquafeed.

There are twomoduleswithin

the GMP + Fee d Cer tif ica tio n

scheme. One GMP+ module

focusesonfeedsafetyassurance

(GMP+FSA)inthewholefeed

chain.ThesecondGMP+module

was been introduced recently

and focuses on responsiblepro-

duction(GMP+FRA)ofanimal

feed.

Feed Safety Assurance(GMP+ FSA)

The Feed SafetyAssurance

module started in 1992 as a

Good Manufacturing Practice

code. Nowadays,

itisawell-elabo-

rated certification

s c he m e f or t he

wholefeed chain,

with a numberof

to ol s in te gr at ed

i n t h is s c he m e .

Fundamental are

HACCP and the

requirements for

q u a li t y m a n ag e -

m e n t s y s t e m s

according to ISO

9001/22000.

In addition, for the different

types of feed companies in the

feed chain, prerequisite pro-

grammes are integrated too.Forassuring a certainlevel of

feedsafety,product standards

(maximum permittedlevelsof

undesirablesubstances) arealso

applicable.Thechainapproachis

crucial,whatthatmeansinprin-

cipleis thatall suppliersin the

chainshouldbecertifiedinorder

to control risks at all stages of

the cha in. All these too ls are

usedfor preventionof contam-

ination. Corrective tools aretraceabilityandtheearlywarning

system, which canbe applied in

caseofoccurrenceofanincident

inorderto avoid furtherdis-

tribution of contaminated feed

products.

Feed ResponsbilityAssurance (GMP+ FRA)

Inordertooffertheinvolved

companies a onestop shop

- multip lecer t i f icat ion pos-

sibi l i ty, GMP+ Internat ionalwi l l integrate responsibi l ity

issues in theGMP+ scheme.

T h e f i r s t s t e p w a s

madeinMarch2013

b y i n tr o du ci n g a

GMP+standardfor

the cha in of cus tod y

for responsible soy

according to RTRS.

Inthesameway,we

wil lcooperate with

Proterra regarding

responsible soy.At

thi s mom ent ,we are

prepar ing a GMP+

s t an d ar d f or t he

c h ai n o f c u st o dy

for responsible f ishmeal and

fishoil.Weintendtolinkthis

standardto exist ingsustain-

a b i li t y s t a nd a r ds r e g ar d i ngf ishing.We intend to imple-

mentthisstandardin2014.

WorldwideAtthis moment, over 12,000

companies in the feed chain,

located in over 65 countries

worldwide, areGMP+FSA cer-

tified.Attheendof2013thefirst

companieswill become certified

againstGMP+FRA.

Multi stakeholdersparticipation

TheGMP+FeedCertification

scheme is managed byGMP+

International.Thisis an interna-

tional, independent organization,

operating on the principle of

well-balanced multi-stakeholders

participation. At this moment,

28tradeassociationsand food

companiesaresupportingGMP+

International.

More InforMatIon:

Website: www.gmpplus.org

Feedsafetyandresponsibilityassurance

AQUACULTURE

UPDATES

Scottishfarmedsalmonproduction

has reached its highest output

since2003.In 2012, the country

produced 162,223 tonnes, an

increase of 2.7 percent on theprevious year. The increased

productionisa537millionboost

fortheScottisheconomy.

FAOhaslauncheditsFisheriesand

Aquaculture document as an

e-book. Compatible with iPad,

Kindle,NookandSonyReader,the

e-booksallowreaderstohighlight

interesting passages, bookmark

pages, makenotes or search the

full-textcontentwithoneclick.The

title,alongwithothers focusingonagriculture and food, are available

todownloadonline.

Bioministoopenanewpremix

plantinVietnaminOctober2013.

The 4.7 hafacility will befitted

with a micro dosing system and

house a laboratory with several

cutting-edgetechnologies,including

a liquid chromatography-tandem

mass spectrometry (LC-MS/MS)

system.

TheMarineStewardshipCouncil

(MSC)has joinedforces with the

BalticSea2020foundationtolaunch

itsprogrammeinPoland.Overthe

nextthreeyears,theMSCwillhelp

build a more sustainable fishing

industryintheregion,andprovide

Polishshoppersmoreopportunities

tochooseecolabelledseafood.

4 | InternatIOnal AquAFeed | Spmb-Ocob 2013

Aqua News


7/68

Anew aquaculture web

libraryhasbeenlaunched

b y t he I n te r na t io na l

CopperAssociation(ICA)underthe directi on of Langley Gace ,

aquacultureapplicationsdevelop-

mentmanager.

TheICA,whichpromotesthe

use of copper worldwide, has

partneredwith theaquaculture

industry to deploy copper-alloy

netsinseveralregionsthroughout

theworld.Theweblibrar y,www.

CuAquaculture.org, provides an

educationalforumtoshareinfor-

mationandupdatesaboutrecent

copper-alloy net installations andmuchmore.

www.CuAquaculture.org aims

to rea ch aquacult ure ind ust r y

professionals , inc luding f ish

farmers, suppliers, scientists,

researchers,educators, non-gov-

ernment organisations, business

consumers andmedia profes-sionalswhoarelookingfortimely

and valuable information about

theindustry.

Thelibraryisreadilyaccessible

andfreetousers24/7.Itcontains

informationabout the scientific

benefitsofcopperalloynetting

for theaquacultureindustry as

wellasavarietyofnewssources

andarticles.Photosandvideosof

recentcopperalloy net installa-

tionscanbeaccessedbyaninter-

activeglobalmap.Thesite alsocontains profiles,

in-deptharticlesandcasestudies

about environmentallyfriendly

andsustainablefish farming

practices,saidGace.

On-linevisitorswilllearn

aboutandexperienceaview

ofthewholecopper-alloynet

installationprocessaswellas

benefits derivedfrom the

useofcopperalloysinfish

farmingpractices.www.CuAquaculture.org

providesahomeincyber-

spaceforawiderangeof

aquaculture educational

information, trade shows,

s e mi n a r s a n d

global forums.

Were contin-

uing to develop

andgather rich

c o n t en t f r o m

a v ar ie ty o f

s o u r ce s . We

also encourage

v i s i t o r s t o

s u b mi t i n f or-

mationforblog

updatesonthe

s i t e s h o me

p a g e , s a i d

Gace.

A d d i t i o n a lr e s o u rc e s o n

t he ne w s i t e

i n c l u d e t h e

history of the

I C A , b e n e fi t s

o f c op pe r i n

a q u a c u l t u r e

i n c l u d i n g a

downloadable PDF describing

the va lue of copp er al loy s in

marine aquaculture, a l ist ing

and description of fish speciescommonlycultivated in aqua-

culture, copperalloynet case

studies, research, aquaculture

newsfromavarietyofcurrent

andglobalsources,andindustry

p r e s s r e l ea s e s a n d c o n ta c t

information.

TheICAsaquacultureon-line

resourcesare already extensiveand will continue to grow.The

goalistomakethissiteasacces-

sible,informationrichanddiverse

astheneedsofthevisitorsusing

it,saidGace.

International Copper Association launches

new aquaculture web library


Aqua News


8/68

view

AQUACULTURE

by Dominique P Bureau,

member of the IAF Editorial

Panel

The potential ofanimal fats as lipidsources in aquafeeds

Formanyyears,mostaquac-

ulturefeedswereformulated

withfishoil(s)asthemain

lipidsource.Foralongperiod,

thesen-3PUFA-richlipidsourceswerecompetitively

pricedcomparedtoother

lipidsourcesandavailability

wasrarelyanissue.Fishoil

productionreacheditspeakat

roughly1millionmetrictonnes

(mmt)anddemand,bothfrom

theaquaculturefeedmarket

andthepharmaceuticalindus-

try,hasincreasedverystead-

ilysincethen.Theincreased

demandandfluctuationsin

productionvolumeshaveled

toavolatileandexpensivefishoilmarket.Thishasforced

manufacturerstogreatlylimit

inclusionoffishoilintheirfeed

formulationsandrelyonadif-

ferent,moreeconomical,lipid

sources.

Therehasbeenmuchresearch

andexchangeabouttheuse

ofplant(vegetable)oilsin

feedsfordifferentaquaculture

species.Studieshavedemon-

stratedplantoilscanbeused

toprovidealargeproportionofthetotallipidsofthediet,

withoutaffectingperform-

anceoftheanimals,aslongas

thenutritionalrequirements,

includingn-3PUFArequire-

ments,aremet.Withthis

information,feedformulators

havestartedusingplantoils

widelyandsignificantlevelsof

plantoilsarenowusedina

verylargeproportionofaqua-

culturefeedsproducedaround

theworld.Theselipidsare,

nevertheless,expensivecom-

modities.Approximately12

mmtofterrestrialanimalfats

aremanufacturedeveryyeararoundtheworldandthese

lipidsourcesaregenerally

moreeconomicalthanplant

oils.Theyhavebeenstaplesin

feedformulationsforterrestrial

animalfeedsformanydec-

ades.Theiruseinaquaculture

feedshasbeenhighlylimited

forvariousreasonsbutthey

deservemoreattentiontoday.

Iamoftenstruckbysomeof

themisconceptionsaboutthe

nutritivevalueofanimalfats

thatareprevalentinthefield

ofaquaculturenutritiontoday.

Ifeelthatsomeoftheviews

needtoberevised.

Thereisarelativelysolidbody

ofevidenceshowingthatthese

lipidsaresafeandcost-effec-

tivelipidsourcesforfishfeeds.

Certainanimalfats(e.g.poultry

fat/oil)haveactuallyfound

wideusewithsignificantsuc-

cessincommercialsalmonand

troutfeedsintheAmericasfor

abouttwodecades.

Anumberofearlystudiessug-

gestedthatterrestrialanimal

fatswereverypoorlydigestible

tofish,notablycoldwaterfish

species,andfeedscontaining

certainamountofanimalfat

didnotsupportoptimalgrowth

performance.Someofthese

earlystudies,includingadigest-

ibilitytrialcarriedoutinour

fishnutritionresearchfacilities

attheUniversityofGuelph,

Canadabackinthe1980s,havereallymadealastingimpres-

siononmanystakeholdersof

theindustry.Numerousother

studies,includingseveralrecent

oneshaveshownthatanimal

fatsareactuallyverywelldigest-

edandutilizedbymanyfish

species,includingrainbowtrout

rearedincoldwater.Whileit

seemsclearthattheapparent

digestibilityoflipidscanbeneg-

ativelycorrelatedtothedietary

inclusionlevelofsaturatedfatty

acids(SFA),resultsfromsome

studiesdonotalwaysappearto

supportthisconclusion.

Sowhatisthesourceofdis-

crepancybetweenstudies?

Afewyearsago,mycolleague

KathelineHuaandIcarriedout

acomprehensiveassessmentof

theeffectofdietaryfattyacids

composition,lipidleveland

watertemperatureondigest-

ibilityoflipidsinfishusinga

nutritionalmodelingapproach.

Theresultsfromthemeta-

analysisofdatafrom16studies

withrainbowtroutandAtlantic

salmonindicatedthatvaria-tionsinapparentdigestibility

ofdietarylipidcanbeprimarily

explainedbytheproportionof

SFAinthetotalfattyacids.A

brokenlineanalysisofthedata

fromthesestudiessuggested

thatSFAcanbeincorporatedin

dietsatlevelsbelow23percent

oftotalfattyacidswithout

negativelyaffectinglipiddigest-

ibility.WhenSFAexceeded23

percentofthetotalfattyacids,

theapparentdigestibilityoflip-

idsdecreasesby1.5percentfor

every1percentincreaseinSFA

contentofthediet.

Theresultsofamultiple

regressionanalysisofdatafrom

thesame16studiessuggested

thattheapparentdigestibility

ofdifferenttypesoffattyacids

differsignificantlyandthe

digestibilityofSFAcannot

beassumedtobeadditive

whenestimatingthedigest-

iblelipidcontentoffishfeeds.

Theanalysissuggestedthatmonounsaturatedfattyacids

(MUFA),polyunsaturatedfatty

acids(PUFA)andincreased

watertemperaturehavea

positiveeffectonthedigest-

ibilityofSFA.Onthebasisof

theresultsfromthemultiple

repressionanalysis,wesug-

gestedthefollowingmodelfor

predictingthedigestiblelipid

contentoffishfeedsonthe

basisoftheSFA,MUFAand

PUFAcontentofthedietandthewatertemperature:

Digestiblelipidcontent(%

ofdiet)=0.45SFA-0.08

SFA2+0.86MUFA+0.94

PUFA+0.03SFA*MUFA

+0.04SFA*PUFA+0.03

temperature*SFA.

Comparisonofmodelpredic-

tionwithdatafromindepend-

entstudiessuggestedthatit

accuratelypredictedthedigest-

iblelipidcontentofdietscon-

tainingacombinationoflipidsourceswithvaryingdietary

lipidcontentfedtorainbow

troutandAtlanticsalmon

rearedatdifferentwater

temperatures.Themodelalso

accuratelypredicteddigest-

iblelipidcontentofdietsfor

severalwarmandcoldwater

fishspecies.Weconcluded

thatthismodelcouldbeavery

simplepracticaltoolforfish

feedformulatorswantingto

explorethecost-effectiveness

ofdifferentlipidsources.

Ofinterestinthismodel(mul-

tipleregressionequation)isthe

positiveeffectofPUFAandMUFAondigestibilityofSFA.

ThesynergisticeffectofPUFA

onthedigestibilityofSFAisa

well-describedphenomenonin

poultry.Itwasdemonstrated

manyyearsago(1962tobe

precise)thatlipidsourcesrichin

SFA,whenusedaloneinthediet,

arepoorlydigestedbypoultry.

However,combiningequal

amountsofalipidsourcerich

inSFA(e.g.tallow)andalipid

sourcerichinPUFA(e.g.soyaoil)generallyresultsinmetabolizable

energy(ME)valuefortheblend-

edfatthatisgreaterthanthe

averageofthetwolipidsources,

hencethetermsynergisticeffect.

Itisclearthatanimalfats

generallycannotbeusedas

thesoleormajorlipidsource

inthedietofmostfishspe-

cies.Feedformulatorsshould

ensurethatdietsareformu-

latedtocontainasufficient

amountofMUFAandPUFAtofacilitatethedigestionof

SFAandtomeettheessential

fattyacidrequirementsofthe

animal.Itismyexperiencethat

goodqualityanimalfatscan

beusedinmanycasesupto

about40oftotallipidsinmany

typesoffishfeeds.

Agreeordisagree?Anyfeed-

back?Pleasedon'thesitate

tocontactmeatdbureau@

uoguelph.ca

view

AQUACULTURE

Have your say

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and click on the

'Aquaculture view' tab,

to see past columns -

and add your comments

to the discussion!

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9/68

AQUACULTUREUPDATES

Researchpublishedin Behavioral

Ecologyand Sociobiology claims

tha t fis h use che mical cue s to

findother fishof the same sizeas themselves.The researchers

exposed fish from two freshwater

shoaling fish speciesto chemical

cuesemittedbyfishofvaryingsizes

fromthesamespecies.

TheJamaicanfisheriessector is

settobenefitfromamulti-million-

dollar investmentin silvertilapia

aquaculture.The funding comes

fromSunshineAquacultureLimited,

in partnership withAquaWilson

Farm, a 100-acrefreshwaterfish

sanctuaryinHillRun,StCatherine.Thecompanieshopethatimproved

effic iencies wil l mean reduced

production costs which can be

passedontotheconsumer.

Molafishhavebeenintroducedto

a beel (swamp) inBangladeshin

a bid to meet growing protein

demand. Under theWorldFish

project, 92 kg of mola f ish fry

wasreleased intothe swamp in

BhelakubaBeelin2012.

Scientists atMakerereUniversity

Agricultural Institute Kabonyolo

(MUARIK), Uganda, havestar ted

rearing the earthworms foruse

in f ish feeds. The demand for

alternative feed ingredients comes

fromfishfarmerswhoarguethat

existing commercial feeds aretooexpensive.

The Nofima Centre for Recirculation in Aquaculture, in Sunndalsra, Norway

Image courtesy of Kjell Merok/Nofima

Alotneeds to happen to

threaten the hegemony

ofthenet-basedproduc-

tion concept in salmon farming,

accordingtoanewreportfrom

Nofima.

Inthe long term, more eff i-

cient land-basedaquaculture can

comeclose.Thescientistsalso

suggest thatland-based aquacul-

ture in countries with low pro-

ductioncostsmaybesomewhatofathreat.

O n c o mm i ss i on f r om t h e

M i ni s tr y o f F i sh er i es a n d

CoastalAffair s,the scientists

evaluatedwhether newoper-

ational conceptswithinaquac-

ulturecouldthreatenNorways

p o si t io n a s a n a q ua c ul t ur e

nation.

Thefollowingsystemshavebeen

evaluated: recirculating aquac-

ulture systems bothin Norway

andincountrieswithlowpro-ductioncosts,offshoreseacages

and closed-containment sea-

basedsystemsinbothexposed

andshelteredlocations.

We see that land-based or

closed-containment sea-based

systems, often using recircu-

latingtechnology,are beingbuilt

in Denmark, North America,

Scotlandand China. Land-based

andclosed-containmentsea-based

systemswillinvolvemuchhigher

investmentcosts,butsomeofthis

disadvantageis expectedto beoffset byloweroperating costs.

However,thereisalongwaytogo

beforeclosed-containment con-

structionswillbeaseconomicalas

todaysnet-based solutions,said

scientistAudunIversen.

Production costTheaverageproductioncostof

the current net-based aquacul-

tureisNOK24perkiloofsalmon

produced.The productioncosts

forthe other conceptsare farmore uncertain. Consequently,

the scientists havedeveloped an

analytical model, whichenables

themtotakemuchof theuncer-

taintyintoconsideration.

Inthefigureabove,weseethat

there are much higher costs in

the closed-containment or semi

closed-containment concepts.

ThecostsareatleastNOK5-10

higher than todays net-based

concept,saidIversen.

Major policy changes, such as

stricter environmental require-ments, maychange thispicture.

Thescientistsalsoenvisagethatthe

technological paradigmshifts, that

willgive considerable changes in

thecostlevel, can haveanimpact

ontheprobabilityofthesuccessof

thevarioustechnologies.

Combination modelsThescientists believe thatwe

willsee examplesof combina-

tion models, where more of the

salmons weight (e.g. up to 1kg)occursin land orsea-based

closed-containmentsystems.

Thishasadvantagesbothfor

the environment of the fish and

that of the surrounding area, as

well as limiting theinvestments

significantlyin relationto having

the entire growth phase in land

orsea-basedclosed-containment

systems.

N or w ay s n a tu r al a d va n -

tage will possibl y beco me less

importantwith newproduction

concepts, but otheradvantagesarealso important forNorways

competitivepositionandarealso

hardtocopy,saidIversen.

Norways salmon farming

industry benefits fromproximity

tothe important Europeanfresh

fish market, strong knowledge

environments, a leading supplier

industry, goodinfrastructure and

good resource management.

Thisbroadcompetencearound

salmonfarmingisalsoamajor

competitiveadvantage.Andthatsdifficulttocopy,ifnotasdifficult

ascopyingthenature.

Anewaquaculturerevolution?


Aqua News


10/68

ScientistsattheUniversityof

Maryland,USAhavedevel-

opeda completely vege-

tarian diet for marine fish raised

inaquaculture.

The f indings led by Aaron

Watson and Allen Place at the

UniversityofMarylandCenterfor

Environmental Science's Institute

for Marine and Environmental

Technology, are published inthe August issue of the journal

Lipids.

"Aquaculture isn't sustainable

becauseittakesmorefishtofeed

fish thanare beingproduced,"

saidDrWatson.

A new vegetarian dietmight change everything

Supportedbyanotherpaper

p u bl i s he d i n t h e J o u r na l o f

FisheriesandAquaculture,the

tea m has proven tha t a com -pletelyplant-basedfoodcom-

b i na t i on c a n s u pp o r t

fast-growingmarine car-

n i vo r e s l i k e c o b ia a n d

g i lt h ea d s e a b r ea m i n

reaching maturityjust as

wellas-andsometimes

betterthan-conventional

diets containing fishmeal

andfishoil.

"This makes aquaculture

completelysustainable,"saidDrPlace.

"The pressure on natural

fisheries interms offood

fishcanberelieved.Wecan

nowsustainagoodprotein

source without harvesting

fishtofeedfish."

T h e t e am s r e se a rc h

c e nt e re d o n e v a lu a ti n g

fishmeal- free, plant pro-

tei n-b ase d die ts or ig ina lly

developed forr ainbowtrout by

the USDA-Agricultural ResearchService and modifying them

to replace the fish oil for cobia

andpotentiallyotherhigh-valuemarinecarnivores.

F i sh m e a l w a s

replacedwithafood

madeofcorn,wheat,

a nd s oy. F is h o il

was replaced with

soybean or canola

oi l , supplemental

l i pi d s f ro m a l ga e

sources, and amino

acid supplements,

suchastaurine.For the consumer,

vegetarian fish have

the added benef it

oflowerPCBsand

mercurylevels.

"Right now, you

are only supposed

to eat str iped bass

o nc e e ve r y t wo

w ee k s, " s a id D r

Place. "You can eat

aquaculture-raised f ish twice

a week becauselevels aresolow."

AQUACULTUREUPDATES

Restaurantmenuscouldholdthe

keyto tracing Hawaii'swild fish

history.ScientistsatDukeUniversity,

USAarehopingtofilla45-year

gapin official wild fish populationrecords bylookingat what was

served in restaurants.Almost 400

menusfrom154restaurantswere

collectedfromholidaymakerswho

tookthemenusassouvenirs.

Prawnandbarramundifarmersin

Australia have moved one step

closer to merging their industry

b od i es . Ta l ks i n C ai r ns a t t he

annual joint conference of the

AustralianPr awn and Barramundi

FarmersAssociationsendedwith

an agreementto forma national

alliance.

A public private-partnership in

Florencia,Columbiaisattemptingto

steerthelocaleconomyawayfrom

cocaand towards silver arowana

aquaculture.Amazon International

Trade, with support f rom the

Columbiantradepromotionoffice,

has started a farm which ison

course toship 20,000 fish a year.Thefish is highly prized in China

whereasinglearowanacansellfor

asmuchasUD$40.

The Univers i ty o f Maine a t

M ac hi as , U SA h as r ec ei ve d a

U S $6 0 0, 0 00 g r an t f ro m t he

Nat ional Sc ience Foundat ion

to stu dy the pot ent ial for new

a q ua c ul t ur e m a r ke t s f or t wo

shellfish in Maine.The research

aimsto improvethe growth and

survivalofbluemusselsandArcticsurfclamsinanefforttocreatenew

economicopportunities.

Veggiedietsforcobia


Aqua News


11/68

Theaquaculturefutureisbrightin

Indiana,USA

Thebusinessofraisingfish

maystillberelativelysmall

inIndiana,USAbutitisa

growingpartofthestate'sagricul-

turaleconomy,aPurdueExtension

reportconcludes.

Estimated sales from Indiana

fish farms amounted to more

than $15 million in 2012, an

increase from $3.5 million in

2006, accordingto thepublica-

tionEconomic Importance of the

Aquaculture Industr y in Indiana .

Thereareabout50fishproducers

inIndiana, comparedwith18just

sevenyearsago.

"While aquaculture is notthemost well-known industry in

Indiana'sagriculturesector,itisdef-

initely present and very impor-

tant to the state's economy,"

KwamenaK. Quagrainie, aquacul-

turemarketingspecialistinPurdue

University's Department of

AgriculturalEconomics,saidinthe

report. Heconductedthe study

withgraduatestudentMeganC.

Broughton.

"Theindustryhasseensteadygrowthover thepast fewyears,

anditisimportanttoknowexactly

howmuch economicactivity is

associated with aquaculture in

Indiana,"saidQuagrainie.

Indiana's aquaculture industry

rangesfromsmall-scaleproducers

raisingfishintheirbackyardsto

large-scale producers growing

fishto sell innational and inter-

national markets, thereport says.

Theindustry includesproduction

offishforhumanfood,ornamentalfishforaquariumsandrecreational

fishthatarestockedinprivateand

publicpondsandlakes.

Raisedforfoodaresuchfishand

shellfish as yellowperch, hybrid

striped bass, tilapia, trout, marine

shrimp and freshwater prawns.

Sport fish includecatfish, large-

mouthbass,smallmouthbassand

sunfishsuchasbluegill.

Thestudymeasuredthesignif-

icanceoftheindustryin2012in

several ways, including the total

incomeof$3.7millionearnedby

169peopleemployed inaquacul-

ture,their$101,506inincometaxes

and$877,908insalestaxesthe

industrygeneratedforIndiana.

ThestudywasfundedbyPurdue

Extension,Illinois-IndianaSeaGrant

andtheIndiana SoybeanAlliance

andwas conductedin coopera-

tionwith the IndianaAquacultureAssociation.

Thesoybeanalliance hasrec-

ognisedaquacultureas"the next

majornew market for soybeans"

andhasaninitiativetohelpthe

industry continueits growth in

Indiana, accordingto thereport.

Itsaysthat1percentoftheUS

soybeancropisusedinaquacul-

tureasfishfeedandthatsoybean

mealisthetopproteiningredient

infishfeedsworldwide.

Indiana soybean and corn

farmers could benefit from a

growing aquacultureindustry, the

reportnotes.Theylikelywouldsee

increaseddemand for soybeans

andcornaswellashigherprices

forthem.

"Eventhoughthefarmerswould

continuetoproducetheirproducts

if theaquaculture industry were

not present, the advantage of

havingalocalmarketingopportu-

nityis veryimportant,"accordingtothereport.

WhatsbehindthedoorsoftheZeiglerBrothersfeed

mill?

TakeasneakpeekbehindthedoorsoftheZeiglerBrothers

feedmill.ThemillinEastBerlinhasbeeninoperationsince

the1970s whenthe originalZeiglerbrothers set up apoultryandlivestockpetfoodoperation.Famouscus-

tomers includePresident Nixonwho neededfeed for

pandasgiventohimChina. Today, themillspecialisesin

bespokefeedsforaquaculture,zooandresearch-labs.

http://bit.ly/19L12Eb

Whathappenswhenasealpup'adopts'salmonfarm

workers?

Theresnothingquitelikeacuteanimalvideotocheer

youupandthisoneisnoexception.InearlyAugust2013,

workersatMainstreamCanada'sRazaIslandsalmonfarm

rescueda sealpup which hadbeen abandonedby itsmother.Thepupadoptedtheworkerswhomanagedto

capturesomeadorablefootageofthesealinaction.

http://bit.ly/147LqX6

Dorainbowtroutlikecoriander?

Researchers at theUniversityof Saskatchewan andthe

DepartmentofAnimaland PoultryScience, Canada, are

studyingnewmethodstoimprovethefattyacidcomposition

offarmedfish.InapaperpublishedintheCanadianJournal

ofAnimal Science, theresearchers documentedtheeffect

ofdietarycorianderandvegetableoilinrainbowtrout.

http://bit.ly/19EH6mx

Can shark-resistant nettinghelpensureresponsible

aquaculture?

Oneof thelimitationsofwarm-wateraquacultureissharks.

Thesecreaturescanchompthroughtraditionalnetsandcages

withease,makingthefishinsideatastyameal.

Totacklethisproblem,DSMDyneema,NETsystemsIncand

theCapeEleutheraInstitutehavejoinedforcestocreateshark-

resistantnetscalledPredator-X.

MadeofDyneemapolyethylenefibresandstainlesssteelwire,

thePredator-X netshaveahighbreakingpoint andandcut

resistant.

http://bit.ly/18kgBj1

Aregularlookinsidetheaquacultureindustry

i i i i ii

ii

ii

ii

i

ii

iiiiiiii

iiiiiiiiii

iiiii i i i i

ii

ii

i

ii

i

i

ii

iiiiiii

iiiiiiii

i

ii

ii i

www.theaquaculturists.blogspot.com

TheRossSeaisthesubjectof

our photo shooton page 32.

TheRossSeaisthemostpristine

ocean remainingontheplanet.

We at International Aquafeed

(IAF)wouldliketokeepitthat

way. Bydevelopingthe potential

thataquaculturehastoofferwe

willultimately takepressureoffoceans,suchastheRossSea,while

meetingthegrowingdemandfor

fishandseafoodinourdiets.IAF

activelysupportsthe work of

'theLast Ocean'charitabletrust

andinparticularlitscreationofa

'no-take marineprotected area'

bymakingregulardonations.We

inviteyoutodothesame.Learn

morenabout'theLastOcean'

here: http://www.lastocean.org/

Take-Action/Donate-__I.1791.

Youcan make a donation here:

https://www.fundraiseonline.

co.nz/fundraise/makedonation_direct.aspx?c=249


Aqua News


12/68

Aquatic animals have various

feeding habits and feed intakes.

For example, fish swallow feeds

so they need about 40minutes

to intake feeds. However, shrimps nibble

feeds so they need three to six hours to

intakefeeds.

The digestive tract of aquatic animals is

relatively short so they have poor digestiveability. For example, fish have no salivary

glandsintheoropharyngealcavitywhichhelps

seek,intakeandswallowfeeds.Sothefunc-

tionsoftearingandgrindingfeedsdegenerate.

Fish dissolve and digest feeds from the

feed surface so aquatic feeds with small

particles are convenient for digestion and

absorption.

These characteristics mean that aquatic

feed pellets should have good stability and

waterresistance;beeasytodigest;andbethe

finenessspecificgrowthstages.

Inordertoproduceidealaquaticfeedpel-lets, feed ingredients, processing technology

andequipmentespeciallythegrindingprocess,

shouldbecarefullyconsidered.

Nutrition sources for feed pelletsRaw materials for pellets should con-

sider not only the nutritional values but

also the needfor good stabilityin water.

Protein, which ensures the growth and

reproduction of aquatic animals, is an

essentialofaquaticfeedpellets.Itaccounts

for 25-50 percent of the feed formulawithwheatandwheatby-productsasthe

mainsourcesofprotein.Iftheviscosityof

proteinisincreasedwhenheated,thenthe

pelletizing performance is improved and

thestabi lity isgood.

Starchis themostcommoncarbohydrate

used in aquatic feed pellets. To ensure the

stability of feed pellets in water, the starch

contentofsinkingfeedpelletsshouldbeup

to10percentandthatoffloatingfeedpellets

shouldbeabout20percent.

Coarsefatisagoodsourceofhighquality

energy.The crudefatlevel includes thefat of

feed ingredients and that of added fat. The

addedfathasgreat influenceonthepelletizingeffectbuttoomuchfatwillmakethefeedpellet

looseandinfluencethestability.Forthisreason,

thecontentofaddedfatshould not exceed3

percent.

Fishmeal is widely used in aquatic feed

pellets.Highqualityfishmealhasgoodwater

resistancequalities.

Similarly, rapeseed dregs contain high

coarsefibrewhichisconducivetoimproving

the water resistance of aquatic feed pellets.

Amongthecommonlyusedfeedingredients

cottonpulp,fishmealandsoybeanmeal,have

good water resistance characteristics whilethe water tolerance of corn, bran and rice

branispoor.

Adding moderate binders can improve

water resistance. There are two kinds of

binders: natural substances such as sodium

ligninsulphonateandalign,andchemicalsub-

stances such as carboxymethyl celluloseand

sodiumpolyacrylate.

So when designingfeed formula theraw

materialsshouldbehighlynutritiousandhave

goodwaterresistanceproperties.

Why is grinding so important?The aquatic feed pellet has highrequire-

ments in terms of particle sizeand viscosity

so the processing technology is important.

In general, feed ingredients for aquatic feed

pellet should be ground to 40 meshes. For

specialaquaticanimalssuchasshrimps,turtles,

eelsandothersmallanimals,therawmaterials

should be super-finelyground so as to pass

througha100meshscreen.Thefinecrushing

granularitycanimprovetheutilizationrateof

aquaticfeedpellet.

Aquaticanimalshavesimpledigestivesys-temandtheresidencetimeoffeedinthegut

isshortsopelletscontaininglargeparticlesare

Grinding equipment for aquatic feed pelletsby Joyce Li, customer service, Amisy Machinery, China

Table 1


FEATURE


13/68

notconducivetoeasydigestion.Thefinerthe

crushinggranularity,thelargerthesurfacearea

whichcontactswiththedigestiveenzymethus

thedigestibilityisincreased.

Raw materials come in different shapes

and thicknesses. So if they are not ground

before processing, the finished pellets canlack a balanced nutritional quality and have

poor stability in water. Table 1 shows the

relationshipbetweenthegrindingfinenessand

stabilityinwater.

Feed pellets have little viscosity when

ground to a large particlesize. Thecrushing

fineness also has an effect on the following

processessuchasmixingandsteammodulat-

ingandthefinenessofpulverizationhasgreat

influenceonstability.Whenthegrainfineness

is perfect, the raw materials can be fully

mixedand theswellingpropertyofmaterials

convergemakingforgoodstability.

Finer particle sizes wil l have a larger

surfacearea which canbe fully modulated,makingbetter-formedpellets.Althoughfiner

particle size isconducivetoproducingfeed

pellets with good stability, the grain size

should not betoo fineotherwise the pel-

leted feeds are fragile. The proportions of

coarse grain, medium grain and fine grain

should be appropriate so that during the

pelleting period the fine grain can fill the

spacebetweenthecoarsegrains.Thismeans

that the contact area between particles is

increasedandthepelletizingperformanceis

improved.

Choosing the appropriategrinding equipment is crucial

Controlling the grinding fineness has a

directinfluenceonthestabilityofaquaticfeed

pellet and the production cost. The impor-

tanceofcost shouldnotbeunderestimated;

electricity consumption during the grinding

process accounts for 50-70 percent of the

totalpowerconsumption.

Choosingthe appropriate grindingequip-

mentisalsocritical.Differentaquaticanimals

havedifferentrequirementsintermsofpar-

ticle size of feed ingredients which requires

corresponding grinding equipment. Hammer

millsarewidelyusedinthefeedindustryand

inaquaticfeeds.Thehammermillconsistsof

hammers, a rotor, the grinding surface and

sieve.Thehammeristhemainworkingpartwhoseshape,size,quantityandlinespeedhas

agreatinfluenceonthegrindingefficiencyand

grindingfineness.Whenthelinearvelocityof

hammerbladeisslower,thegrindingefficiency

andproductionefficiencyarelow.

A quicker line speed will improve grind-

ing efficiency. However, too high a speed

will make the material speed fast, reduce

Figure 1


FEATURE

Extruder OEE for the Production of Fish FeedExtruder OEE for the Production of Fish Feed

AMANDUS KAHL GmbH & Co. KG, Dieselstrasse 5-9, D-21465 Reinbek / Hamburg,

Phone: +49 40 727 71 0, Fax: +49 40 727 71 100, [email protected] www.akahl.de


14/68

the grinding efficiency, increase the power

consumption and increase the energy con-

sumptionofproducts.Theoptimallinespeed

should consider factors such as the power

consumption, grinding fineness, noise and

productionefficiency.

The number of hammers has a great

effect on the grinding fineness and crushing

efficiency.Outsimply,morehammersmeans

faster and finer grinding. Fewer hammers

resultsinacoarserproduct.

Meshscreenand sieves arerelatedto

the grinding fineness . Figure 1 shows the

relationship between grinding fineness of

corn, bean pulp and the mesh screen

diameter. The smaller the diameter of

meshscreen,thefinerthegrindingfineness

and the lower the output. In turn, when

the diam eter isbig ,the grindin gfineness is

coarseandtheoutputishigh.Thesizeof

meshscreendiameterisdeterminedbythe

requiredsizeof the finalpellet soin the

context of meeting the grinding finenessoffeedpellets a sievewith big diameter

should beadoptedso asto improve the

crushingefficiencyandreduceenergycon-

sumption.

Studiesshowthatwhenthesieveareais

increasedby9percent,thegrindingefficiency

can be improved by 35 percent and the

electricityconsumptioncanbereducedby13

percent. So choosing the appropriate sieve

areacanimprovetheoutput.

In addition, the thickness of sieve influ-

ences the sieving ability of materials. There

isacorrespondingandrestrictiverelationship

betweenthesievethicknessandthediameter

ofmeshscreen:sievethicknessislessthanor

equaltothediameterofmeshscreen.

The fineness requirement of ordinary

aquaticfeedpelletis40-60mesh.Inorder

to achi eve the ideal crushing fine ness and

avoid the super-f ine grinding of materi-

als, the grinding surface shape should be

changed.Awaterdropgrindingsurfaceis

widely adopted in producing the aquatic

feedpellets.Awaterdropsieveshapecan

increase the effective sieve area, destroy

the circ ulat ion layer of mate rials so as

to change the materia l moto r directi on,

increase the frequency of hammer grind-

ing the materials and improve crushing

efficiency.

Grinding machine optionsMachine for fine grinding have a higher

spindlespeed,morehammersnumbersanda

widergrindingsurfacethanmodelsforcoarse

grinding.

The Amisy ser ies of AMS-ZW-29C,

AMS-ZW-38CandAMS-ZW-50Chammer

millscanbeusedforcoarsegrindingoffeed

ingredients.

The main

differences

o f t he t hr eemodels are

the gr ind ing

r oo m w id th ,

hammer

blade quan-

ti ty , po wer .

Thewiderthe

grindingroom,

the higher the

crushing eff i-

ciency. More

hammers

wil l producefiner prod-

uc ts th oug h

of course the

higher power

means the

moreoutput.

The Amisy

ser ies of

AMS-ZW-

60B a nd

AMS-ZW-

80B ham-mer mills are

m ai nl y u se d

forfinegrind-

ing. The out-

put differenc-

es between the two models are related

to the powe r, grinding room width and

hammernumbers.

TheAMS-ZW-80Bmodelhasmoreham-

mers, a wider grinding surface and greater-

power than thatof the AMS-ZW-60B. This

means that the output of AMS-ZW-80B is

greaterthanthatofAMS-ZW-60B.

Both the ser ies use the water drop

design to ensure a largerspace for grind-

ing and to improve crushing eff ic iency.

The crushing fineness differencesbetween

the two models mainly lie in the spindl e

speed,hammer numbers and grinding sur-

facewidth.

Producing fine feedsAsmentionedpreviously,aquaticanimals

suchasshrimps,eelsandturtlesrequirefine

feeds. For these animals, grinding fineness

mustbeupto80mesh.Ordinaryhammer

mills cannot reach this fineness so ultra

fine feed grinding equipment is necessary.Toachievetherequiredsmallparticlesize,

ingredients should be crushed twice. An

initial coarsely grinding can be done by a

hammer mil l with a second grind on an

ultrafinemill.

Ultra fine grinding equipment uses the

blade type. The grinding chamber and

grading room of Amisys AMSSWFL42,

AMSSWFL75, AMSSWFL102 and

AMSSWFL128 models are located in the

samemachinebodysothatcrushing,grad-

ingandseparationcanbecompletedsimul-taneously. The main differences between

the three models lie in feeding motor

power,sievingmotorpower,rotordiame-

terandrotorspeed.Whenthero torspeed

isfasterthegrindingfinenessisfinerbutthe

grinding efficiency and output are accord-

ingly reduced. Compared with other feed

hammer mills, the ultra fine feed crushing

millhas a loweroutputbecausetherotor

speedisfaster.

The main indexto evaluate the working

efficiency of feed grinding equipment is the

grindingfineness,outputandpowerconsump-tion.Grinding finenesshas greatinfluence on

the feed utilization, production properties

of aquatic animals, feed pellet quality and

productioncost.

Considering factors such as the mesh

screen,hammerquantity,spindlespeed,grind-

ingsurfacesizeandchoosingtheappropriate

powerbasedonthecompositefactors,grind-

ingcanproducehomogenouspellets,improve

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Intensive production of mainly car-

nivorous fish has resulted in fish feeds

containing high levels of fishmeal and

fish oil, with Europe requiring around

1.9million tonnesa year.Althoughthis use

offishmealwasinitiallytherecyclingofwaste

fromfishingthrough theuseofbycatchand

trimmings, duetotherapiddevelopmentofaquaculturethisrelianceonfishmealandfish

oilisenvironmentallyunsustainable.Thishas

resultedin othersources offish feedbeing

investigated.This literaturereviewwill focus

on microalgae; the composition in terms

of nutritional quality, the current methods

of production and associated costs along

with potential future uses such as feed in

aquaculture.

Algae overviewMarine algae are distributed from the

polarregionstotropicalseasinnutrientrich

andpoor environments. Algae arephotoau-

totrophs and are characterised by their lack

ofroots,leavesandpresenceofchlorophylla.

Theyrangeinsizefrommicroscopicindividual

cells called microalgae to seaweedsthat can

begreaterthan30minlength(Qin2012).

Marine microalgae are the dominant

primary producers in aquatic systems and

accountforasimilarlevelofcarbonfixationas

terrestrialplants(40-50%)butrepresentonly

1 percent of the planetary photosynthetic

The potential of microalgae meals incompound feeds for aquacultureby Nathan Atkinson, MSc Sustainable Aquaculture Systems student, Fish Nutrition and Aquaculture Health Group, PlymouthUniversity, United Kingdom

able 1: mino acid profile of different algae as compared with conventional protien sources and the WH/F (1973) reference pattern (g per 100protein)

Source Ile eu Val ys Phe yr Met Cys ry hr la rg sp Glu Gly His Pro Ser

WH/F 4.0 7.0 5.0 5.5 6.0 3.5 1.0

gg 6.6 8.8 7.2 5.3 5.8 4.2 3.2 2.3 1.7 5.0 - 6.2 11.0 12.6 4.2 2.4 4.2 6.9

Soybean 5.3 7.7 5.3 6.4 5.0 3.7 1.3 1.9 1.4 4.0 5.0 7.4 1.3 19.0 4.5 2.6 5.3 5.8

Chlorella vulgaris 3.8 8.8 5.5 8.4 5.0 3.4 2.2 1.4 2.1 4.8 7.9 6.4 9.0 11.6 5.8 2.0 4.8 4.1Dunaliella bardawil 4.2 11.0 5.8 7.0 5.8 3.7 2.3 1.2 0.7 5.4 7.3 7.3 10.4 12.7 5.5 1.8 3.3 4.6

Scenedesmus obliquus 3.6 7.3 6.0 5.6 4.8 3.2 1.5 0.6 0.3 5.1 9.0 7.1 8.4 10.7 7.1 2.1 3.9 4.2

rthrospira platensis 6.7 9.8 7.1 4.8 5.3 5.3 2.5 0.9 0.3 6.2 9.5 7.3 11.8 10.3 5.7 2.2 4.2 5.1

phanizomenon sp. 2.9 5.2 3.2 3.5 2.5 - 0.7 0.2 0.7 3.3 4.7 3.8 4.7 7.8 2.9 0.9 2.9 2.9

Figure 1: Percentages (dry weight basis) of protein, lipid and carbohydrate inmicroalgae. The range of values is shown by range bars (Brown 1997)


FEATURE


17/68

biomass(Stephenson2011).Microalgaeare

sometimesdirectly consumedby humans as

healthsupplementsduetothishighnutritional

valueandabundance(Dallaire2007)butthis

isrelativelyrare.

Ascarnivorousfishingestalgaeasafood

source (Nakagawa 1997) there has been a

movetoutilisethemforfishfeed.Currently

30 percent ofthe worldalgalproductionis

usedfor animal feed(Becker 2007)but theuse in aquaculture is mainly for larval fish,

molluscs and crustaceans (FAO 2009a). As

mentionedabove,thefishmealandoilusein

aquaculture is unsustainable and algae have

thepotentialtoreducethisdependence.This

isdue tothe algaebeing photosyntheticso

they have the ability to turn the suns huge

amountofenergy,120,000TWofradiation,

intoprotein,lipidsandnutrients.Moreenergy

from the sun hits the surface of the earth

in one hour than the energy used in one

yearandthisisahugeamountofuntapped,

sustainableenergycanbeexploitedbyalgae.Thisisarelativelynewareaofresearchbut

hasmanypositiveaspectsthatgiveitalarge

amountofpotentialforfutureuse.

MicroalgaeThe term microalgae is often used to

referspecificallytoeukaryoticorganisms,both

fromfreshwaterandmarineenvironmentsbut

canincludeprokaryotessuchascyanobacteria

(Stephenson 2011). Microalgal production

hasreceivedsomeattentionrecentlydueto

itspotentialuseasabiofuel(Slocomb2012),useinanimalfeed,humanconsumptionand

recombinant protein technology (Becker,

2007;Potvin andZhang 2010;Williamsand

Laurens, 2010). This has resulted in a huge

amount of knowledge and research into

microalgae and

resulted in reviews

being published

about specific sub-

jectssuchasgenetic

engineering of algae

(Qin 2012), poten-

tial use as biofuel

(Demirbas 2011)

and novel methods

to measure such

important com-

ponents such as

protein (Slocomb

2012).

Thisinterestand

knowledge in the

area ha s allowed

aquaculture to

essentiallypiggyback

the research being

performed by thebiodiesel industry

andeven actsyner-

gistically with it by

consuming the by-

products produced

(Ju2012). Currently

micro al ga e hav e

been used in aqua-

culture as food

additives, fishmeal

and oil replace-

ment, colouring ofsalmonids, inducing

biological activities

and increasing the

nutritional value of

zooplankton which

are fed to fish lar-

vaeandfry(Dallaire

2007).

A lt ho ug h t he

biodiesel industry

hasbeenconduct-

ingalargeamount

o f r es ea rc h, t hi sh as m ai nl y b ee n

f oc us ed t ow ar ds

species that have

high lipid contents

whereasspeciesin

aquaculture must

be of appropriate

s ize for ingestion

and be read-

i ly digested. They

must also have

rapidgrowthrates,beabletobecul-

tur ed on a mas s

s ca le , b e r ob us t

eno ug h t o co pe

with f luctuat ions

able 2: il contents of some microalgae(Demirbas 2007)

Microalgae il content (wt% of dry

basis)

Botryococcus braunii 25-75

Chlorella sp. 28-32

Crypthecodinium cohnii 20

Cylindrotheca sp. 16-37

Dunaliella primolectra 23

Isochrysis sp. 25-33

Monallanthus salina >20

annochloris sp. 20-35

annochlorosis sp. 31-68

eochloris oleoabundans 35-54

itzschia sp. 45-47

Phaeodactyhum tricornutum 20-30

Schizochytrium sp. 50-77etraselmis sueica 15-23


FEATURE


18/68

in temperature, l ight and nutrients and

haveagoodnutrientcomposition(Brown

2002).

Varying nutritional valuesThe nutritional value of any algal species

dependsonitscellsize,digestibility,produc-

tion of toxic compounds and biochemi-

cal composition. This,along with differences

among species and method of production,

explains the variability in the amount of

protein, lipids and carbohydrates, which are

12-35 percent, 7.2-23 percent, and 4.6-23

percentrespectively(FAO2009a)(Figure1).

Thisleveloffluctuationcan beinfluencedby

thecultureconditions(Brownet al.,1997)but

rapidgrowthandhighlipidproductioncanbe

achievedbystressingtheculture.

Protein

Mostofthefigurespublishedinthelitera-tureontheconcentrationofalgalproteinsare

based on estimations of crude protein and

as other constituents of microalgae such as

nucleic acids, amines, glucosamides and cell

wallmaterialswhichcontainnitrogen;thiscan

resultinanoverestimationofthetrueprotein

content(Becker2007).

Thenon-proteinnitrogencanbeupto12

percentinScenedesmus obliquus,11.5percent

inSpirulina and6percentin Dunaliella.Even

with thisoverestimationthenutritionalvalue

of the algae is high with the average qual-

itybeingequal,sometimesevensuperior,to

conventional plant proteins (Becker 2007)

(Table1).

The amino acid composit ion of the

proteinissimilarbetweenspeciesandis

relativelyunaffectedbythegrowthphase

andlightconditions(Brownet al.,1993a,

b ). A sp ar ta te a nd

glutamate occur in

the highes t concen-

tr at io ns (7 .1 -12. 9% )

w he re as c ys te in e,

m et hi on in e, t ry p-

tophanandhi st id ine

occurinthelowest

concentrations(0.4-3 .2 %) w it h o th er

aminoacids ranging

f ro m ( 3. 2- 13 .5 %)

(Brown1997).

LipidsThelipidsinmicro-

algalcellshaverolesas

both energy storage

molecules and in the forma-

tion of biological membranes

and can be as high as 70percent dry weight in some

marine species (Stephenson

2011)(Table2).Underrapid

growth conditions these lipid

levelscandropto14-30per-

cent dry weight, which is a

level more appropriate for

aquaculture. These lipids are

composedofpolyunsaturated

fatty acids such as docosa-

hexaenoicacid(DHA),eicos-

apentaenoic acid (EPA) and

arachidonicacid(AA)(Brown2002) and in high concen-

trations; most species have

percentagesofEPAfrom7-34

percent(Brown2002)(Figure

2).

These fatty acids arehighly sought after

andastheycurrentlycannotbesynthesised

in a laboratory and are usually obtained

through fish oil and are a limiting factor in

vegetable oils such as palm, soybean and

rapeseed oil use in aquaculture. The fatty

acid composition is associated with lightintensity, culture media, temperature and

pH.Appropriatemeasuresandcontrol,along

with the suitable selection of a species, is

necessarytoproducealgaewiththedesired

lipidlevelandcomposition.

VitaminsMicroalgaealsocontainvitaminswhichcan

bebeneficialtothehealthoftheconsumerbut

vary greatly between species (Brown 2002).

This variation is greatest for ascorbic acid

(VitaminC), whichvaries from1-16mg g dry

weight(Brown&Miller,1992),butothervita-

minstypicallyshowa2-4xdifferencebetween

species(Brownet al.,1999)(Figure3).

Despite the variation in vitamin C all the

species would provide an adequate supply to

cultured animals which are reported to only

require0.03-0.2mgg-1ofthevitaminintheirdiet

(DurveandLovell,1982).Howevereveryspecies

ofalgaehadlowconcentrationsofatleastone

vitamin(DeRoeck-Holtzhaueret al.,1991)soa

carefulselectionofamixedalgaldietwouldbe

necessarytoprovideall thevitaminstocultured

animalsfeedingdirectlyonmicroalgae.

Algae in aquacultureTheuseofalgaeasanadditiveinaqua-

culturehasreceivedalotofattentiondueto the positive effect it has on weightgain,

increased triglyceride and protein deposi-

tion in muscle, improved resi stan ce to

disease, decreased nitrogen output into

the enviro nment, increased fish diges tibili ty,

physiological activity, starvation tolerance

andcarcassquality(Becker,2004;Fleurence

2012).Li(2009)showedthattheaddition

ofdriedmicroalgaeinthediet,albeitatlow

concentrations 1.0-1.5percent, resulted in

increasedweightgainofthechannelcatfish

(Ictalurus punctatus) along with improv-ing the feed efficiency ratio and levels of

poly-unsaturatedfattyacids.Ganuza(2008)

showedthatalgaloilcanbeanalternative

sourceofDHA(docosahexaenoicacid)to

fishoilingiltheadseabream(Sparus aurata)

microdietsalthoughitdidnotallowforthe

complete substitutionof fisheries products

duetothelowEPA(eicosapentaenoicacid)

levelsinthespeciesofalgaeused.

These were at relatively low-level inclu-

sions; at greater levels it can have a detri-

mentaleffect.At12.5percentinclusionalgae

causedreducedgrowthperformancesinrain-bowtroutandat25percentand50percent

thissubstitutionoffishfeedcausednutritional

deficiencies that led to decreased growth,

feedefficiencyandbodylipids(Dallaire2007).

Levels of algal inclusion of 15 percent

and30percentalsoreducedfeedintakeand

growth rate in Atlantic cod (Walker 2011).

AsAtlanticcodareknowntohavearobust

digestivesystemitwassuggestedthatthiswas

duetoreducedpalatabilitywhichcouldbean

issueforalgaluseinaquaculture.

High levelsof inclusiondoes not causesuchnegativeeffectsinallspeciesraisedin

aquaculture, 50 percent replacement did

not have a negative effect on shrimp (Ju

2012),butisgenerallyexperiencedamong

finfish.

Figure 2: Average percentage compositions of the long-chain PUFAs docosahexaenoic acid (DHA; 226n-3),

eicosapentaenoic acid (EPA; 20:5n-) and arachidonic acid(20;4n-6) of microalgae commonly used in aquaculture.Data compiled from over 40 species from laboratory of

CSIRO Marine Research.

Figure 3: Concentrations of different vitamins inmicroalgae in g g-1. Graph adapted from Brown

2002 with data collected from Seguineau et al.,1996 and Brown et al., 1999


FEATURE


19/68

Algae productionThe production of algae, in particular

microalgae, is a rapidly developing industry

dueto thebiofuelresearch thatis currently

takingplace. Theannual worldproductionof

allspeciesisestimatedtobe10,000tyear-1

(Richmond,2004)withthemainlimittopro-

ductioncurrently being thecost. Production

costsarecurrentlyrangefromUS$4-300per

kg dry weight (FAO 2009a) depending on

the type of production method employed

(Table3).

There has been a shift away from typical

systemssuchasoutdoorpondsandraceways

to large-scale photobioreactors which have a

muchhighersurfaceareatovolumeratioand

could potentially reduce the production cost

(Brown 2002).These photobioreactorscould

yield19,000-57,000litresofmicroalgaloilper

acreperyear,whichisover200timestheyield

fromthebestperformingvegetableoils(Chisti

2007), and reduce the cost of algal oil from

$1.81to$1.40perlitre(Demirbas2011).However, for algal oil to becompetitive

withpetrodiesel,itshouldbelessthan$0.48

perlitre.Thisisachievablethrougheconomies

ofscale(Demirbas2011)andwouldmakeita

cheapand sustainableoilfor theaquaculture

industry.Therearealsootherdevelopments

such as increasing thespecific activity ofthe

enzyme RUBISCO which would increase

yields, transgenic studies, increasingthe pro-

portion of photo protective pigmentswhich

wouldimprovethelight-dependantreactions

and selecting for algae with small antennas

whichis fundamentalto achievinghighyields

inbiomassdensecultures(Stephenson2011).

This research is essential as the production

costs of microalgae are sti ll too high to

competewithtraditionalproteinsourcesfor

aquaculture(Becker2007).

Benefits and obstaclesAlgae have a great potential for use in

sustainableaquacultureastheyarenotonlya

sourceofprotein,lipidsandhaveothernutri-

tional qualities but they are phototrophic so

producethesedirectlyfromsunlight.Producing

100 tons of algal biomass also fixes roughly

183tonsofcarbondioxidewhichhasobvious

implicationsinthisperiodofclimatechange.

The production does not always require

freshwater, compete forfertileland and are

not nutritionally imbalanced with regard to

theaminoacidcontentlikesoybean.Therearestillsomeobstaclessuchasthe

powder-likeconsistencyofthedriedbiomass

and applications to feed manufacture, the

production costs and pests and pathogens

that will effect large scale algal cultivation

sustainability(Hannonet al.,2010),whichisan

areathatlittleisknownabout.

Therestillneedstobemanyfeedingtrials

as the majority of research has focused on

improving the nutritional value of rotifers

and not asalgaeas a potential replacement

offishmealandfishoil.Thereisalsointerest

intostoringalgalpasteswhichhaveextended

shelflife(2-8weeks)ortheuseofdefattedmicroalgaemealfromthebiodieselindustry.

Theuseofalgaeinaquacultureisapromis-

ing and young area of research and when

compared to agriculture,which has increased

cropproductivityby138percentina50year

period,itdemonstratesthegreatpotentialthat

algaehas.

Referencesavailableonrequest


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N

owadays, all animal production

is concernedwith vaccination.

This is an essential technique

forthe protectionof livestockhealth which, however, entails significant

costs for stock breeders. Maximizing the

efficiency and profitability of prophylactic

vaccination strategies is therefore a major

stake. To achieve this, new avenues are

constantlyexplored.Oneoftheseconcerns

istheuseofnewmoleculesextractedfrom

seaweeds to help optimize the stimulation

ofthenaturaldefencesofthebodyandits

responsetovaccinationstrategies.

Innate immunityThebodysresponsetotheaggressionofa

pathogenisbasedontwotypesofimmunity.

Theyaretheinnateimmuneresponseandthe

adaptiveresponse.

The innate response is the first line of

defence against pathogens. It is activated

immediately and acts very quickly. This

immune response can be found in all ani-

mals. It will be the same whenever thebody encounters that pathogen. However,

the body does not retain a memory of the

infectiousagent.Themechanismofactionof

this type of immunityconsists in recognizing

the molecular patterns shared by numerous

pathogens, which areessentially represented

bymembranefractions(glycocalyx).

The various elements that contribute to

theinnateimmuneresponsearethefollowing:

Physical barrier (mucous membrane,

skin,mucus,villietc) Phagocyticcells,suchasthemacrophages

Naturalkiller(NK)cells

Certain cytokines, which deliver signals

warningthebodyofadanger

Complementsystem

Toll-like receptors (TLR), a family of

membrane receptors only discovered

recently. They control the expression

ofmoleculesthatfightagainstinfectious

agents(directlyorindirectly,viaeffectorcells,andbyrecruitingtheactivationof

theadaptiveimmunesystem).

The elements associated with the innate

immune response can act on the pathogen

directly or indirectly, by producing effector

cells (cytokines etc). The latter will subse-

quently trigger the adaptive immunity by

activatingtheTandBcells.

Adaptive immunityUnliketheinnateresponse,theacquiredor

adaptiveresponseoccursinvertebratesonly.Duringthefirstencounterwithagivenpatho-

gen(primaryinfection), itacts as thebodys

second line of defence. Its activation takes

sometime-knownaslatency.However,this

response system memorizes the pathogens

it encounters and when the body is again

exposedtothemthelatencyismuchshorter

andtheimmunesystemreactstotheaggres-

sion almost immediately. Adaptive immunity

isspecific:itrecognisesthemolecularpatterns

ofthealreadyencounteredpathogens.

The various elements that contribute to

the adaptive immune response are the fol-lowing:

Tcells

Bcells

Antibodies

Ig,TCR, CTL,antibody (AB)-producing

plasmacells+coupledaidoftheinnate

immunityeffectors

Seaweeds: a new source ofactive elements to stimulatethe immune system

In recent years more and more publica-tions have brought to the forefront the

relevanceofseaweedsinnumerousbiological

applications, particularly to immune mecha-

nisms,takingspecialinterestin someoftheir

components, namely the sulfated polysac-

Marine algal polysaccharides:a new option for immune stimulation


FEATURE

NK : Natural KillerPRR : Pattern Recognition Receptor

CMH : Complexe Majeur dhistocompatibilitTCP : T Cell Receptor


21/68

charides. These are complex carbohydrates

whichdonotoccurinterrestrialplants.They

aresupposedtoinfluencetheimmunesystem

by a vastnumber of stillpoorlyunderstood

pathways.

Polysaccharides represent a structurallydiverse class of macromolecules which are

relatively widespread in nature. There are

simpleandcomplexformsofpolysachharides.

Unlike proteins and nucleic acids, polysac-

charidescontainrepetitivestructuralfeatures

whicharechainsofmonosaccharideresidues

joinedtogetherbyglycosidicbonds.

Thus,theyformpolymer(-type)structures

representedintheformofchainsthatmaybe

homogenous (homopolysaccharides) or not

(heteropolysaccharides). The simple forms

are the homopolysac-

charides composed of

a single type of sugar,

linked in an essentiallylinear manner (starch,

glycogen, cellulose for

ex ampl e). T hey a re

essential ly structural

compounds or mecha-

nismsofenergystorage

in an easily releasable

form. Their structure

may become more

complex owing to their capacity to

establishlinks at various levels of each

elementary unit, allowing thus the

development of branching structures

inthethreedimensions.Thesearethe

branchedheteropolysaccharides.

Structural variability andbiological potentialities

Thenucleotidesinnucleicacidsand

the amino acids in proteins can inter-

connect in only one way, while the

monosaccharide units in oligosaccha-

ridesandpolysaccharidescanintercon-

nect atseveralpoints toforma wide

varietyoflinearorbranchedstructures

(Sharon and Lis 1993). For instance,

the number of possible permutations for

four different sugar monomers can attain


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Innate immunity / cquired immunity: wo complementary and cooperative systems

Innate immunity daptive or acquired immunity

Chronology

Primary infectionQuick response: first

barrier against pathogensSecond line of defence : latency

(about 7 days)

epeated infectionsIdentical to the primary

responseImmune memory => atency

close to zero

Specificity on-specific response Specific response (Ig and C)

ecognized molecular patterns Invariable and common tonumerous pathogens

Specific to the infectious agent

Cellular and molecular effectorsComplement, phagocyticcells and certain cytokines

C (cytotoxic cells) and anti-body producing plasma cells,

with the help of innate effectors

C : Cell eceptor - Ig : Immuno Globulin - C : Cytotoxic ymphocyte or Killer cells

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up to 35,560 unique tetrasaccharides, whilefour amino acids canform only 24 different

permutations(Hodgson1991).

Thisexplainsthefactthat,amongmacro-

molecules, polysaccharides provide thehigh-

est capacity for carrying biological informa-

tion, as they have the greatest potential for

structural variability. In addition, one of the

particularitiesthatnumerousmarinepolysac-

charidespossessistheirpolyanioniccharacter,

whichconfersthemahighchemicalreactivity.

Of these anionic polysaccharides, the

majority of those which occur macroalgae

are sulfated polysaccharides: galactan (agar,carraghenans),ulvans,fucans.

Theulvans,forexample,thewater-solublepolysaccharides found in green seaweed of

the order Ulvales (Ulva and Enteromorpha),

havesulfate,rhamnose,xyloseandiduronic

and glucuronic acids as their main constitu-

ents (Lahaye and Ray 1996) (Percival and

McDowell1967).

Ulvan structure shows great complexity

andvariabilityasevidencedbythenumerous

oligosaccharide repeating structural patterns

identified(LahayeandRobic2007).Themain

repeating disaccharide units reported are of

ulvanobiouronicacid3-sulfatetype,containing

eitherglucuronicoriduronicacid.Inaddition,a few repeating patterns can be foundthat

contain sulfated xylose replacinguronic acid

orglucuronicacidon theO-2binding/linkof

therhamnose-3-sulfateunits(LahayeandRay

1996)(Lahayeetal.1997).

InterestsThishugevariabilityinthepolysaccharide

structure providesthe flexibility requiredfor

exactregulatorymechanismsindifferentcell-

cellinteractionsinhigherorganisms.

Sulfation in particular seems to be con-

ducive to various biological activities noted

in polysaccharides extracted from marine

macroalgae.

Marine sulfated polysaccharides:their role and effect on immunity

Sulfatedpolysaccharides, which arewide-

spread in macroalgae, have been shown

to possess anti-infectious (Cumashi et al.

2007)(WitvrouwandDeClercq1997)(anti-

viral, anti-bacterial, anti-tumoral), antioxidant

(Wangetal.2010)(deSouzaetal.2007)andanti-thrombotic (Ma

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