they are what they eat - enhancing the nutritional value of live feeds with microalgae

7/30/2019 They are what they eat - Enhancing the nutritional value of live feeds with microalgae

1/9

May | June 2013They are what they eat - Enhancing

the nutritional value of live feeds withmicroalgae

The International magazine for the aquaculture feed industry

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 ofinformation published.Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any formor by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

INCORPORAT ING

f Ish fARmING TeChNOlOGy
http://www.aquafeed.co.uk/http://www.aquafeed.co.uk/


2/9

www.oj-hojtryk.dk

Die and roll re-working machines

O&J Hjtryk A/S

rnevej 1, DK-6705

Esbjerg

CVR.: 73 66 86 11

Phone: +45 75 14 22 55

Fax: +45 82 28 91 41

mail: [email protected]

O&J HJTRYK A/S endeavours to be a powerful, vigorous

and energec company. With our customers needs and the

immediate environment as our point of departure, we want

to be a trendseer in our core area of business - Mechanical

Engineering - Re-working of Dies and Rollers for the

manufacture of Feedstuffs and Biopellets, as well as the sale

and delivery of wearing parts in connecon

with Roller Re-working - as well as to

remain open to new iniaves and

business opportunies.

O&J HJTRYK A/S has drawn up a

strategy plan se ng out guidelines for

how we as an organisaon must conduct

and develop ourselves in order to make

our mark, not just in the present, but also in the

future.

O&J HJTRYK A/S must achieve success by adapng

to the condions of the market more quickly

and effi ciently than our competors. As a service

organisaon we must, in relaon to our customers,aach great importance to our own vitality and effi ciency

by constantly living up to the ever-growing demands made on

the services we provide.
http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/http://www.oj-hojtryk.dk/


3/9

Today the most costly and

perhaps least understood live

food are the unicellular algae

- Dhert & Sorgeloos 1995

Live feeds are often essential for

larval fish. Live feeds are proven

to be essential first-feed for many

larval fish, essentially all those that

hatch from small eggs with limited yolk

reserves and often immature feeding and

digestivefunctions.Livefeedsprovidelarval

fishwithessentialnutrientsthatarenaturally

microencapsulated in bite-sized packages.

They include a high proportion of easily-

assimilated free amino acids and free fatty

acids, as well as digestive enzymes and

beneficial bacterial microfloras in the gut

contentsoftheprey.Theswimmingactivity

oflivepreyalsostimulatesfeedingresponses

inlarval fish, a vitalconcernbecause small

larvaewithverylimitedmetabolicreserves

can quickly starve iftheydo not promptly

beginfeedingactively.

Thenaturallivefoodsofsuchlarvaeareof

coursemicroplankton,bothzooplanktonand

(althoughoftennotappreciated)phytoplank-

ton. Natural zooplankton assemblages areoftenhighlydiverseandmayincludeprotozoa,

rotifers,arroworms,microcrustaceanssuchas

copepods,andeggsandlarvaeofnearlyevery

group of marine animals including sponges,

coelenterates, polychaetes, various crusta-

ceans, molluscs, echinoderms, andeven fish.

Thisdiversearrayofpreyorganismssupplies

multiplesourcesof essentialnutrients.But it

canbeverydifficulttoobtainsufficientnatural

planktonto supplytheneedsof ahatchery,

andnaturalplanktoncanintroducepredators,

parasites and pathogens. Hatchery-cultured

livefeedsarethereforetheonlypracticaland

safefeedformanylarvalfish.

Use of live feeds in aquacultureByfarthemostcommonly-usedlivefeeds

in hatcheries arerotifers (Brachionus spp.)

andbrineshrimp(Artemia)(Conceioet

al.2010),withsomeuseofcopepodssuch

as species ofAcartia, Calanus, Tisbe, and

Parvocalanus . Although copepods gener-

ally provide better nutritional value, their

culture presents so many difficulties that

they are not commonly used in hatcheries

(Drilletetal.2006,2011).Rotiferscanread-

ily bemass-cultured at high densities and

candoubletheirnumbersinaday.Rotifers

are smaller than newly-hatched Artemia,

which can be too large for some larvae.

Artemia aremostconvenientbecausetheir

restingeggs (cysts) can be purchased and

hatchedwhen needed, but newly-hatched

Artemia naupliido notbeginto feed until

afterthefirstmolt,sotheirnutritionalvalue

dependsentirelyonthenutritionalenviron-ment ofthe previouswild generationthat

produced theeggs.Onestudy found that

the content of the important omega-3

Poly-Unsaturated Fatty Acid (PUFA) EPA

inArtemia cystsfromthesamesourcecan

varyasmuchas44-fold(Dhert&Sorgeloos

1995).Suchvariationsmeanthatthenutri-

tional content of newly hatched Artemia

may be largely unknown, and only after

the first molt can their nutr itional value be

improvedbyfeeding.

It is important to understand that nei-

ther Brachionus rotifers nor Artemia are

truly marine organisms. Rather they are

found in saline habitats, which are mostly

inland environments with often extreme

seasonal variations in temperature, salinity,

and even availability of water. Adaptation

to such extreme conditions has endowed

these species with characteristics that are

veryusefulinaquaculture,suchastolerance

ofawiderangeofcultureconditions,rapid

asexual reproduction by parthenogenesis

(Brachionus),andformationofresistantrest-

ingcysts(BrachionusandArtemia).Theyare

alsorelativelyomnivorousanddonothave

stringent nutritional requirements, and so

canbefedonlow-costfeedssuchasyeast,

starch,ricebran,anddriedSpirulina(cyano-

bacteria).

Itmaybe nosurprise that feeding larvae

only one or two species of hatchery-pro-

ducedlivefeedsmightnotprovideadequate

nutrition. But the underlying cause of such

nutritionalinadequacyisoftenthelowquality

of the low-cost food sources used to pro-ducethelivefeeds.Itisthereforenecessary

to choose carefully the food sources used

for hatchery-produced live feeds if they are

to provide adequate nutritional support for

larvalfish.

They are what they eatEnhancing the nutritional value of

live feeds with microalgaeby Eric C Henry PhD, research scientist, Reed Mariculture Inc., USA

12 | ItrtIol AquAFeed | May-June 2013

FEATURE


4/9

Innovations for a better world.

Bhler AG, Feed & Biomass, CH-9240 Uzwil, Switzerland, T +41 71 955 11 11, F +41 71 955 28 96

[email protected], www.buhlergroup.com

Fatten up your bottom line. Bhler high-performance animal and aqua feed production

systems are used by leading companies around the world. These producers know they

can rely not just on the technology itself, but also on the support that accompanies it. A

service combining local presence with global expertise both lowers feed mill operating

costs and increases capacity utilization. To nd out more, visit www.buhlergroup.com
http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/http://www.buhlergroup.com/


5/9

Limitations of formulated feedsfor live feed production

Formulatedfeedsofferlowcostandcon-

venience, but they have fundamental short-

comings. Zooplankton,including rotifers and

Artemia,canfeedonlyonmicroparticlesof

appropriatesize(frombacteriato10mfor

Brachionus [Baeret al. 2008, Vadstein et al.

1993],andfrombacteriato28m,withthe

optimumabout8-16mforArtemia [Makridis

and Vadstein 1999, Fernndez 2001]). It is

difficult to produce dry feeds that provide

uniformparticlesizes,andevenwhenuniform

dry particles can be produced they can be

subject to clumping when dispersed into

waterforfeeding.Butprobablythemostcriti-

calshortcomingofdryfeedsisrapidleaching

ofwater-solublenutrients;thesmallerthepar-

ticle,thefasternutrientsareleachedout.Not

onlyareleachednutrientsunavailabletothe

livefeeds,theycancausefoulingofthewater.

Rotifer Brachionus

plicatilis Algae concentrate (ReedMariculture Tetraselmis 3600)

May-June 2013 | ItrtIol AquAFeed | 13

FEATURE
http://www.andritz.com/


6/9

Lipidemulsionsofhigh-PUFAoilsmaybe

usedtoimprovethefattyacidprofileoflivefeeds.Althoughtheircontentsarenotsubject

to leaching, lipiddroplets are prone to stick

tosurfaces, including thewallsoftheculture

tankand the live feedorganisms themselves.

Lipid enrichment protocols therefore often

must include a rinsing step to clean the

rotifersorArtemia ofadheringlipiddroplets,

which would otherwise foul the larval tank.

Short-term feeding of oil emulsions results

in lipid-enriched rotiferswith high EPA and

DHA levels, but, they are prone to rapid

loss of their gut contents and acquire an

extremelipid:proteinratio(Dhertetal.2001).

Moreover,ithasbeenshownthatwhenthe

rotifersarecollectedonscreens,astheyare

for rinsing, this mechanical stress can cause

ejection of the nutritious gut contents that

were ingested during enrichment feeding

(Romero-Romero& Yfera 2012), defeating

thepurposeoftheenrichment.

Advantages of microalgaeMicroalgae are the base of the plankton

foodweb,andtheirgreatbiochemicaldiver-

sityisthesourceofthehighnutritionalvalueof natural zooplankton.As the natural food

ofzooplankton,microalgaeofferanumberof

advantagesover formulated feeds. Theyare

naturalmicroencapsulationparticlesbounded

by a cell membrane that retains the nutri-

tiouscontents.Theynaturallycontainawide

spectrumofnutritionalcomponents, suchasessentialaminoacids,PUFAs,sterols,vitamins,

andphytopigments.Differentspeciesprovide

a wide range of cell sizes and nutritional

factors,aswellascomponentsthatenhance

digestion and immune functions (Guedes

& Malcata 2012). Some strains have been

foundtohaveantibacterialeffects(Austin&

Day1990,Kokouetal.2012,Regunathan&

Wesley2004).

Selecting the right microalgaeAlthough hundreds of microalgae strains

have been tested as feeds for aquaculture,

fewerthan20areinwidespreaduse(Guedes

& Malcata 2012). Because these strains

vary so greatly in their nutritional profiles,

careful consideration is necessary in order

to select the most nutritionally appropri-

ate strains. Such algae as Spirulina, Chlorella,

Haematococcus,andDunaliellaareeasilymass-

produced because they can be cultivated

inopenpondsatlowcost,buttheyalllack

theomega-3PUFAsEPAandDHA thatare

essential for production of live feeds that

provide adequate nutrition to marine fish.High-PUFAalgaein wideuse include strains

of Nannochloropsis (Eustigmatophyceae),

favoured for rotifer production and green-

water;Tetraselmis(Prasinophyceae); Isochrysis

andPavlova(Prymnesiophyceae);Thalassiosira,

Chaetoceros, and

Skeletonema (diatoms);

and Rhodomonas

(Cryptophyceae).

Although the PUFA

contentofmanystrains

hasbynowbeenwell-

documented, sterol

profiles have been

more challenging to

characterise because

thereisfarmorestrain-

to-strainvariation,even

among strains suppos-

edly of the same spe-

cies, as revealed in a

recent investigation of

over100diatomstrains

(Rampen et al. 2010).

Protein content is less

variable,withastudyof

40strainsofmicroalgae

in seven algal classesfindingconsistentlyhigh

contents of essential

amino acids (Brown

et al. 1997). Vitamin

contents of microalgae

alsoappeartobecon-

sistently high (Brown

& Miller 1992, Brown

etal.1999,DeRoeck-

Holtzhaueretal.1991).

Although various nutritional components

havebeenwell-documentedinmanystrains,

it remains difficult to assemble complete

nutritionalprofilesofmanystrainssothatthe

optimalcombinationofstrainscanbeselected

for a particular application. It is unfortunate

that so many studies of the nutritional per-

formance of microalgae have tested single

strains as the only feed,when it should be

obviousthatnosinglestrainislikelytoprovide

an optimal nutritionalprofile comparable to

that provided by a natural phytoplankton

assemblage.

In practice, microalgae have repeatedly

beenshowntodramaticallyimprovethePUFA

contentofrotifersandArtemia (Chakraborty

et al. 2007, Ferreira et al. 2008, Kjell et al.

1993,Lieetal.1997,ieetal.1994,Reitanet

al.1997),whichfrequentlyresultsinimproved

larval performance. But it is important to

recognise that thehighnutritionalquality of

enriched live feeds can bemaintained after

deliverytothelarvaltankonlybyapplication

ofgreenwatertechniques.Unlessmicroalgae

are added tothe larval tank water, the live

feed organisms quickly begin to starve, and

canmetabolize a significant fractionof theirbiomassbeforetheyareeatenbythelarvae.

Thealgal cells themselves canalso function

aslivefeeds,sincetheyhavebeenshownto

beeatenanddigestedbylarvae(Reitanetal.

1997,VanDerMeerenetal.2007),andmay

Nauplius stage of copepod

Parvocalanus crassirostris

14 | ItrtIol AquAFeed | May-June 2013

FEATURE


7/9
http://www.muyang.com/


8/9

also stimulate digestive enzyme production

(Cahuetal.1998).

Production of microalgaeDespitethemanyadvantagesofmicroalgae,

theirwideruse is hampered by difficulties in

culturing, storage, and high costs. Microalgae

culturecanconsumeasignificantfractionofthe

resources of a hatchery, andrequires special

equipment, skilled labour, anda large alloca-

tionof space that is unproductiveduringthe

seasonswhenlivefeedsarenotneeded.

Low-cost open-pond culture methods

carryhighrisksofcontaminationandculture

failureduetotheimpossiblityoftightlycon-

trollingcultureconditions,andthemosthighly

prizedhigh-PUFAstrainssuchasIsochrysisand

Pavlovarequireindoorculture.

Itisverydifficulttosynchronizemicroalgal

production with live feed requirements to

preventfeed shortagesor wastefuloverpro-

duction,and itis difficultto accurately dosealgae culturesdirectlyinto livefeedcultures.

If thealgae areharvestedand concentrated,

thetightly-packedcellscandeterioraterapidly

inrefrigeratedstorage.Somemicroalgaehave

been freeze- or spray-dried, but dried cells

aresubjecttoproteindenaturation,andwhen

they are rehydrated the leaching of water-

soluble substances can rapidly deplete their

nutritionalvalue,aswithotherdryfeeds.

Microalgae concentratesThe best solution to these problems

canbe theuse ofcommercially-available

refrigeratedorfrozenalgaeconcentrates

or pastes (Guedes & Malcata 2012,

Shields&Lupatsch2012).Theseproducts,

which are actually viscous l iquids, have

proventobeeffectivefeedsforrotifers,

Artemia,shellfishandotherfilter-feeders,

aswellasforgreenwaterapplications.

In products formulated to provide a

longshelf-life,theconcentratedmicroalgae

are suspended in buffer media that pre-

servecellularintegrityandnutritionalvalue,

although the cells are non-viable. When

concentrates with well-defined biomass

densities are employed, the algaecan be

accurately dosed into l ive feed cultures

with a metering pump, and non-viability

confers the advantage that the products

pose no risk of introducing exotic algal

strains.Thebestrefrigeratedproductstypi-cally have a shelf-life of 3-6 months, and

frozenproductsseveralyears.Thismeans

that a reli able supplyof algae canbe kept

onhand,availableforuseinanyseasonor

ifanunexpectedneedarises.Algaecosts

become predictable, and often prove to

belessthanon-siteproductionwhentotal

production costs and inefficiencies are

accountedfor.

Although costs of liquid algae concen-

trates are higher than for dried algae or

formulatedfeeds,theyofferallthenutritional

advantages of live cultures. The nutritional

quality oflive feedscanbe nobetterthan

the food sources used to produce them.

Success of earlylarvae isso critical tothe

successofahatcherythatevenarelatively

smallimprovementinsurvivalorgrowthrate

canyieldgreatbenefits.

OutlookLive feeds remain indispensable for

larvicultureofmanyfish.Althoughmicro-

algaeareamongthecostliestfoodsources

used to produce l ive feeds, their many

advantages justify the cost for hatcheries

producinghigh-valuefish.Researchcontin-

ues to better characterise the nutritional

properties of various algaestrains and to

optimise algae production technologies.

We can ant icipate that introduct ion ofnovel algae strains and nutritionally-opti-

misedcombinations of strains, alongwith

improved feeding protocols, will ensure

thatmicroalgaeremain thefoodof cho ice

for production of the highest-quality live

feeds.

Referenceswww.aquafeed.co.uk/referencesIAF1303

May-June 2013 | ItrtIol AquAFeed | 15

FEATURE

Naturally ahead

MYCOFIX

Mycoto

xinRisk

Ma

nag eM

en

t

Mycofix

More protective.Mycotoxins decrease performance and interfere

with the health status of your animals.

Mycofx is the solution for mycotoxin risk management.

mycofx.biomin.net
http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/http://mycofix.biomin.net/


9/9

www.aquafeed.co.uk

LINKS

Seethefullissue

VisittheInternationalAquafeedwebsite

ContacttheInternationalAquafeedTeam

SubscribetoInternationalAquafeed

They are what they eatEnhancing thenutritional valueof livefeeds

with microalgae

Controlling mycotoxins with

binders

Ultraviolet

water disinfection for fish

farms and hatcheries

Niacin one of thekey B vitaminsfor sustaining

healthyfish growth andproduction

Volume 16 I ssu e 3 2013 - mAY | J uNe

INCORPORAT ING

fIsh fARmING TeChNOlOGy

Thisdigitalre-printispartoftheMay|June2013editionofInternational

Aquafeedmagazine.

Contentfromthemagazineisavailabletoviewfree-of-charge,bothasafull

onlinemagazineonourwebsite,andasanarchiveofindividualfeaturesonthedocstocwebsite.

Pleaseclickheretoviewourotherpublicationsonwww.docstoc.com.

Topurchaseapapercopyofthemagazine,ortosubscribetothepaper

editionpleasecontactourCirculationandSubscriptionsManageronthelink

above.

INFORMATIONFORADVERTISERS-CLICKHERE
http://www.aquafeed.co.uk/http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/http://www.aquafeed.co.uk/contact.phphttp://www.aquafeed.co.uk/subscriptions.phphttp://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/iaf1102http://www.docstoc.com/profile/Perendalehttp://www.aquafeed.co.uk/advertising.phphttp://www.aquafeed.co.uk/advertising.phphttp://www.docstoc.com/profile/Perendalehttp://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/subscriptions.phphttp://www.aquafeed.co.uk/contact.phphttp://www.aquafeed.co.uk/http://www.aquafeed.co.uk/iaf1102http://www.aquafeed.co.uk/

they are what they eat - enhancing the nutritional value of live feeds with microalgae

Documents