January | February 2014

EXPERT TOPIC - SHRIMP

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 of information published. ©Copyright 2014 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

INCORPORAT ING f I sh fARm ING TeChNOlOGy

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Welcome to Expert Topic. Each issue will take an in-depth look at a particular species and how its feed is managed.

SHRIMPEXPERT TOPIC

1GlobalEMS Impact on global shrimp industry and future prospects

by Dr Farshad Shishehchian, president and CEO of Blue Aqua International and president-elect of the Asia Pacific Chapter of the World Aquaculture Society

The early mortality syndrome (EMS) in shrimp has been ravaging pro-duction systems, spreading verti-cally in Asia and horizontally to

countries as far away as Mexico since first reported in 2009.

LookingattheimpactofEMSonthethreelargest global shrimp producers – Thailand,Vietnam and China - there have been sub-stantial effects on supply and prices to theglobalshrimpmarket.

"Thailand used to be the largest shrimpexporterwithover500,000metrictonnesofshrimpproduction.

"In2013,itsproductionfellalmost50per-centfromthepreviousyearbecauseofEMS.ThisoffersawindowofopportunityforotherpotentialshrimpproducerssuchasIndonesia,India and Ecuador. Indonesia farmers haveexperiencedthehighestprofitrecordintheirshrimphistoryasaresult.

"Culture expansion is putting in full forceduring this lucrative period. India is another

potential producer tokeepaneyeon.Sincethepermission of vannameiculture a few years back,India increased its shrimpproductionbymore thantwofoldlastyear.Ecuadorispushingwithmuchhigh-er production in thepasttwoyears."

Inconclusion,andduetotheimpactofEMS,DrShishehchia says shrimpprices will continue theirhigh level for some timebecauseoftheinsufficientsupply.

"This is likely to con-tinue until Thailand, theworld’s leading shrimpexporter and most tech-nologically advanced pro-ducer, gets into recoverymodeandcreatesashiftinsupplyandprices."

However, the long-term impact will beconsolidationandintegrationofshrimpfarms.The current disease situation and environ-mentwill push for consolidation in themar-ket.Small farmswithoutaquaculturepracticestandards and sufficient funds will be drivenout of the business. Those large farms withstrong finance, good farm management, lowcost,highaccesstomarketswillbethefutureoftheshrimpindustry,headds.

EMS ForumAsian Aquaculture Network (AAN), in

corporation with International Aquafeedand the Association of InternationalSeafood Professionals is organising a EMSForum: 'Managing the Shrimp Epidemic' interms of bringing practical solutions to theshrimp industry. The forum will be held onMarch 28-29, 2014 at KU Home, KasetsartUniversity, Bangkok, Thailand. This eventis supported by Department Fisheries ofThailand, Department Fisheries of Indonesia,ShrimpClubofIndonesia(SCI)andBlueAquaInternational. Participants are expected fromIndia,Vietnam,Malaysia andMexico in addi-tiontoIndonesiaandThailand.

Dr Farshad Shishehchian President and CEO of Blue Aqua International and President-elect of the Asia Pacific Chapter of the World Aquaculture Society

(right) with Tuti Tan of International Aquafeed magazine, Roger Gilbert President of Association

of Sdeafood Professionals and publisher of IAF and Nun Chongwitookit, Marketing Communications

at Blue Aqua International during the APA13 exhibition in Ho Chi Minh City, Vietnam in

December 2013

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32

1

Biofloc systemsUsing super-intensive biofloc systems for Pacific white shrimp production

by Tzachi Samocha, Terryl Hanson, Timothy Morris, Vitalina Magalhães, Bob Advent and André Braga, Texas A&M AgriLife Research Mariculture Lab, Flour Bluff, Texas, USA

The demand for protein by anincreasing world population –together with decreasing harvestsfrom fisheries – has resulted in

rapid growth of aquaculture. Global aquac-ulturecurrentlyaccounts for40percentofseafoodproductionandprovides60percentofshrimpdemand.Theworldshrimpfarmingindustry’sannualgrowthoverthelastdecadehasbeenestimatedat10percent.Therapidexpansionofthisindustryhasstimulatedtheintensificationofproductionsystems,whichhas unfortunately resulted in the releaseof nutrients and organic waste, and some-times the spread of diseases, all damagingreceiving streams.Uncontrolledgrowthhasimposed heavy losses, and raised majorcriticismsthatthreatenfurtherdevelopmentof the industry.Toreduce losses todiseaseoutbreaks, producers have been lookingfor more sustainable and cost-effectivepractices.

Despite the world trend in favour ofaquaculture, in the United States the sectorhasshownnosubstantialgrowth.Thecountrythus remains a net seafood importer, withannual shrimp imports of 1.2 billion lbsworth $4.5 billion. New approaches mustbedevisedifUSshrimpfarmingistoavoidtheenvironmentaldrawbacksoftraditionalflow-throughponds.USsystemsmusthaveaverylowimpactontheenvironmentandfully contain – rather than export – anywater quality or disease problems thatarise. One approach is to shift from low-intensityoutdoorpondstosuper-intensiveindoor recirculating aquaculture systems

(RAS). With little or evenno water exchange, properlymanaged RAS thus reducesor eliminates the amount ofnutrientsreleasedtotheenvi-ronment,escapeofnon-nativeculture species, and spreadof pathogens to the environ-ment.Becauseofthesefactorstheyeasilyconformtoeffluentstandards set by the nationalregulator.

Biofloc technology (BFT)systems are a special type ofRAS that maintain a commu-nityofsuspended(flocculated)microalgae and autotrophicand heterotrophic bacteria(“biofloc”) together with theshrimp in limited-exchangegrow-out units. Pacific whiteshrimp (Litopenaeus vanna-mei) growth rates are muchhigher in BFT systems thanin clear-water systems, and higher still atgreater floc levels. The composition of thebiofloc affects nutrient cycling. Heterotrophsandautotrophsarepreferred in flocsystemsbecause they provide two very importantservices: they assimilate ammonia and nitrite(bothhighlydeleterioustoshrimp),andactasasupplementalfeed.

Biofloc success: a water quality issue?

Feed and feeding practices are importantfactors affecting water quality and profit-ability of any aquaculture operation, moresowhen dealing with hyper-intensive, biofloc-dominated systems. As mentioned above,shrimpcanderivenutritionalbenefitsfromthemicrobialaggregatesinBFTsystems.Studiesinourlabalsoshowedgoodshrimpgrowth(2.4gperweek)andsurvival(96.8percent)when5 percent of the fishmeal in a 35 percentcrudeproteindietwasreplacedwithbiofloc.However, this replacement resulted in areductioninshrimpgrowth(0.4gperweek)comparedtothecontroldietwithnofishmealreplacement.Analysisofthebioflocproducedin our system suggested low protein (20.4percent), lowfat(0.29percent)andhighash(43.4percent)content.

Becausefeedrepresentsoneofthemajor

costs in shrimp production, accounting forover50percentofthetotalproductioncosts,it can significantly affect profitability. Theinteractionsbetween feed,waterquality andproductivity have been evaluated in relationto the characteristics of each culture systemresulting in the development of speciallydesigned feeds to enhance shrimp perform-anceineachsystem.

Theeffectsofcommercialfeedsonwaterqualityandshrimpperformanceareimportantfactors affecting feed formulations. The endproductoffeedcatabolismisammonia,whichcanbetoxictoshrimp.Ebelingetal.describethreepathwaysforammoniaremovalintradi-tionalaquaculturesystems:photoautotrophic,autotrophicandheterotrophic.Thedominantof these pathways in BFT systems can beaffectedbybioticandabioticfactors.

With an adequate supply of organiccarbon, heterotrophic bacteria can quicklyconvert (in around 8 hours) all availableammonia into bacterial biomass, a processwhichrequiresalargeamountofoxygenandthe generation of high volume of bacterialbiomass. On the other hand, when organiccarbon is provided solely from feed, anyammonianotconsumedbytheheterotrophicbacteriawillbeslowlyconverted intonitratebyautotrophicbacteria.Thisnitrificationproc-

2 table 1. litopenaeus vannamei performance in a 92-d grow-out trial in four 40 m3 rWs stocked with juveniles (1.2 g) at a density of 530/m3 and operated with no water exchange

ID Wt(g)

Growth(g/wk)

Yield(kg/m3)

Sur.(%) FCr

Water Use(l/kg

Shrimp)

St 18.45a 1.27 8.96 84.4 1.28 148

FF 17.35b 1.26 8.24 80.2 1.35 149

* Values with different superscript letters indicate stat

table 2. Summary of a 108-d grow-out study performed in 2009 with juveniles (0.99 g) litopenaeus vannamei stocked at 450/m3 under no water exchange

tank IDav. Wt. Growth Survival Yield

FCro2

Usage

(g) (g/wk) (%) (kg/m3) (lPM)*

rW (St) 21.88 1.37 94.5 9.43 1.58 0.17

rW (FF) 22.45 1.37 96.6 9.63 1.55 0.27

table 3. Combined mean production values from two grow-out studies conducted in 2011 with juveniles litopenaeus vannamei from Fast-Growth (a) and taura resistant lines (b) in the 40 m3 and the 100 m3 raceways.

SystemVolume n Density

(shrimp/m3)Salinity(ppt)

Initial Wt. (g)

Final Wt. (g) Days Growth

(g/wk)Sur.(%)

Yield(kg/m3) FCr

40 m3 4 500a 18 1.9 23.2 82 1.82 82.3 9.5 1.43

40 m3 1 500a 30 1.4 25.1 85 1.95 78.9 9.9 1.44

100 m3 2 390b 30 3.1 25.3 106 1.46 83.0 8.4 1.77

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ess,whichconsumesalkalinityasaninorganiccarbon source, requires far less oxygen andproducesaround40 times lessbacterialbio-massthantheheterotrophicpathway.Whenoperating biofloc systems under low lightintensitywithrestrictedorganiccarbonsupply,autotrophic and heterotrophic bacteria willdominate the microbial populations. Thesemixotrophicsystemsrequirecarefulmonitor-ing and control of selected water quality tomaximiseproduction.

2007-2011: early studiesIn recent years, studies at the Texas

A&MAgriLifeResearchMaricultureLabhavefocused on the use of a commercial feedmade by Zeigler Bros. (HI-35, Zeigler Bros.,Gardners, PA) formulated for use in high-density, biofloc-dominated no-exchange sys-tems for the production of market-size L.vannamei. These studies were conducted infour to six greenhouse-enclosed 40m3/68.5m2raceways.Eachlinedracewayisequippedwithacentrelongitudinalpartitionpositionedover a5.1 cmPVCpipewith spraynozzles.Everytankhadsixbanksofthree5.1cmairliftpumps positioned equidistantly on each side

ofthepartition.Inaddition,eachracewayhadsix0.91cmlongairdiffusers,a2hpcentrifugalpump,andaVenturiinjectorcapableofintro-ducingatmosphericairoramixtureofoxygenandair.The following isa short summaryofthe progress made in operating this systemoverthelastsixyears.

The2007studywasconductedinfourofthe raceways described above, which wereequipped with the YSI 5200 inline dissolvedoxygen monitoring system. The tanks werestocked to a density of 530/m3 with 1.2 gjuveniles using water from a 77-day nurserytrial. The study compared two methods ofbiofloccontrol:homemadefoamfractionators

and settling tanks. Shrimp were fed on theHI-35 feed mentioned above. Until Day 73(estimated7kgshrimp/m3),oxygendemandwas met solely by the Venturi injector andatmospheric air. From Day 74 on, atmos-pheric air was enriched with pure oxygen.Thedissolvedoxygenmonitoringsystemwasinstrumentalinmanagingfeedandpreventinglowoxygenevents.All shrimpsubmitted fordisease diagnosis showed no signs of viralinfections.Theresultsfromthistrialaresum-marizedinTable1.

In2009asecondstudywasconductedtodeterminewhetherornotsmallercommercialfoam fractionators (in the case, Aquatic Eco

Figure 1: Ammonia-N (100 m3 RWs) Figure 2: NO2-N (100 m3 RWs) Figure 3: NO3-N (100 m3 RWs)

Figure 4: Alkalinity (100 m3 RWs) Figure 5: Turbidity (100 m3 RWs) Figure 6: TSS (100 m3 RWs)

Figure 7: VSS (100 m3 RWs) Figure 8: SS (100 m3 RWs)

44 | InternatIonal AquAFeed | January-February 2014 January-February 2014 | InternatIonal AquAFeed | 45

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A two-day VietFish Conference ‘Fishfarm Management & Fish Marketing’ - August 7 & 8, 2014Organised on behalf of VietFish 2014 by the Association of International Seafood Professionals (AISP) and International Aquafeed magazineVietnam, with its population base of 90 million people, produces for domestic markets and export markets US$6.7 billion of farmed fi sh products. Of its exports 21 percent goes to the EU, 19 percent to the USA and 16 percent to Japan. Currently, Vietnam exports 40 percent of its shrimp production and 30 percent of its Pangasius. Vietnam is aiming at achieving food security in fi sh by 2020. The industry faces challenges in the area of disease, production costs, meeting market requirements, fi nancial resources and value chain developments. This conference aims to address several of these issues for producers and marketers. www.en.vietfi sh.com.vn

Systems’ VL65 fractionator) could be usedto minimise the differences in shrimp finalweightsobservedinthe2007study.The108-daystudywasconductedinthesamefour40m3 raceway tanks equipped with the previ-ously described YSI 5200 dissolved oxygenmonitoringsystem.Racewayswerefilledwithwaterfromapreceding62-daynurserystudy,andstockedtoadensityof450/m3with0.99g juveniles. Freshwaterwasaddedweekly tooffsetwaterlosses.ShrimpwerefedthesameHI-35 feed mentioned earlier. Settling tanksand the foam fractionators were operatedintermittently,targetingtotalsuspendedsolidsconcentrations between 400 and 600 mg/L.The results showednosignificantdifferencesinshrimpfinalweightsbetweentheracewaysoperatedwithsettlingtanksandthoseoper-atedwithfoamfractionators.Furthermore,nostatistically significant differences were foundin shrimp performance between treatments(seeTable2).

In an effort to reduce production costs(e.g. the use of pure oxygen and electricity)thelabbegantotestnon-Venturiinjectorsforaerationandmixingintwo100m3racewaysunderbioflocconditions.These injectors (a3,All Aqua Aeration) are currently used inseveralwastewater treatment facilities in theUnited States and require little maintenancecomparedtootheraerationandoxygenationmethods.Thistechnologymaybesuccessfullytransferredtobioflocandothertypesofaqua-culturesystems.Basedonthemanufacturer’sspecifications, the injector provides a 3:1air-to-water ratio, compared with the <1:1capacityofourVenturi-driven system,whichrequires the use of pure oxygen to main-tain desired dissolved oxygen levels at high

biomass loading(> 6 kg/m3). Eachtank was equippedwith 14 injectors,and one injectorpowering a home-made foam frac-tionator for biofloccontrol. Racewayswere stocked to adensity of 270/m3with8.5g juvenilesand were fed theZeiglerBros.HI-35feed. At the endof the 87 days ofthe 2010 trial, ayield of 6.4 kg/m3was obtained frommarketable shrimp(26.1 g), with 90.1percent survivalrate and a feedconversion ratio of2.46.

Thetrialin2011was conductedin five of the 40m3 raceway tanksdescribed above,filledwithamixtureofseawaterandbiofloc-richwaterpreviouslyusedina42-daynurserytrial.Salinityinfourofthetankswasadjustedto18partsperthou-sand using chlorinated municipal freshwater.Racewayswere stocked to a density of 500shrimp/m3with1.90gjuveniles.Forcompari-son,afifthtankwasoperatedwithsalinityof30partsperthousand,andstockedwith1.40

gjuvenilesstockedatadensityof500/m3. All raceways were stocked withshrimpfromaFast-Growthlineprovid-ed by the Oceanic Institute, MakapuuPoint, Hawaii. Shrimp were fed thesameHI-35feedasinpreviousstudies.The raceways were operated with nowater exchange throughout the study.Results from this study showed highyields of food size shrimp, with goodgrowth,survivalandFCR(seeTable3).

Thesecond2011trialwasconduct-ed in the two 100m3 EPDM rubber-lined raceways, each filledwith amix-tureofseawater,municipalchlorinatedfreshwater,andbiofloc-richwaterfroma previous nursery study. The tankswere stocked with 390 shrimp perm3, with Taura-resistant L. vannameijuveniles (1.90 g) supplied by ShrimpImprovement System, Florida. Shrimpwere fed the same HI-35 feed usedin previous studies. Raceways wereequipped with the YSI 5200 dissolvedoxygen monitoring systems and weremaintained with no water exchange

throughoutthe106-daydurationofthestudy.TheresultsaresummarisedinTable4.

2012: trials point to commercial viability

Thestudiesin2012usedbothsystemsfortheproductionofmarketableshrimp.Thefirststudywas conducted in six 40m3 racewaysandhadfourobjectives:1. Evaluate the effect of two commercial

feeds on juvenile shrimp producedfromacrossbetweenFast-GrowthandTaura-Resistantlines

2.Monitor the changes in selectedwaterqualityindicatorsundernoexchange

3.MonitorL.vannameiperformanceunderhighdensityandnoexchange

4. Evaluate the benefit of using the YSI5500 continuous dissolved oxygenmonitoring system with optical probeinoperatingabiofloc-dominated,super-intensiveshrimpproductionsystem

Thesecondstudytookplaceinthetwo100m3racewaytanksandhadthreeobjectives:1. Evaluate the performance of the same

juvenile shrimp used in the previousstudy under the same stocking den-sitywhen fedtheHI-35 feedundernoexchange

2. Further evaluate the ability of the a3injectors to maintain adequate mix-ing and dissolved oxygen levels in ahigh-density, biofloc-dominated, zero-exchangeconditions

table 4. Summary of mean final weight, weekly growth, yield, survival, FCr, and water usage from a 67-d grow-out study of litopenaeus vannamei in 40 m3 greenhouse-enclosed raceways operated with no water exchange.

FeedYield Survival av. Wt. Growth

FCrWater Use

(kg/m3) (%) (g) (g/wk) (l/kg shrimp)

HI-351 9.74 87.3% 22.12 2.03 1.25 124.7

SI-352 8.71 88.3% 19.74 1.76 1.43 138.3

Diff 1.03 2.38 0.27 0.18 13.6

1RWs where shrimp were fed the HI-35 Zeigler Bros. feed2RWs where shrimp were fed the SI-35 Zeigler Bros. feed

table 5. Summary of litopenaeus vannamei) performance following a 63-d grow-out period in two 100 m3 raceways using the a3 injectors for mixing and aeration.

rW

Stocking Harvest Growth Survival Yield

FCrWater Use

(l/1 kg)(Juveniles

/m3) (g) (g) (g/wk) (%) (kg/m3)

1 500 3.6 22.76 2.13 80.82 9.20 1.43 139.5

2 500 3.6 22.67 2.12 78.19 8.86 1.53 148.9

average 22.72 2.12 79.50 9.03 1.48 144.2

table 6. Summary of production and sales for super-intensive biofloc dominated no exchange shrimp production systems comparing the results from the 2011 trial to the 2012 trials.

treatment 2011 HI-35 40 m3

SI-35 40 m3

HI-35 100 m3

Stocking density (Juvenile/m3) 500 500

0%5000%

5000%

Survival rate (%) 81.6 87.3

+7.0%88.2

+8.1%79.5-2.6%

Growth rate (g/wk) 1.85 2.03

+9.7%1.76-4.9%

2.13+15.1%

Stocking size (g) 1.8 2.7

+50%2.7

+50%3.6

+100%

Harvest size (g) 23.6 22.3

-5.5%19.8

-16.1%22.7-3.8%

FCr 1.43 1.25-12.6%

1.430%

1.48+3.5%

Crop length (days) 83 67

-19.3%67

-19.3%63

-24.1%

Production (kg/m3) 9.58 9.74

+1.7%8.71-9.1%

9.03-5.7%

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3.EvaluatethebenefitofusingtheYSI5200continuousdissolvedoxygenmonitoringsysteminoperatingthesystem

We also aimed at reducing FCRs belowthe values achieved in the previous trials,primarilythroughcontinuousfeeding.

The six 40 m3 raceway tanks were filledwithamixtureofwaterused inapreceding49-daynurserystudy,seawaterandmunicipalfreshwater to reach a salinity of 30 partsper thousand. Each tank was equipped witha small commercial foam fractionator and ahomemade settling tank. Shrimpused in thisstudywereproduced froma crossbetweenTaura-resistantandFast-GrowthgeneticlinesdevelopedbyShrimp ImprovementSystems.Racewayswerestockedwith2.66gjuvenilesatadensityof500shrimp/m3.Thestudywasperformedwiththreereplicatesusingasemi-intensive feed (SI-35) which had 35 percentcrudeprotein,7percent lipidand4percentfibre,andahyper-intensivefeed(HI-35)with35 percent crude protein, 7 percent lipidand only 2 percent fibre, both produced byZeiglerBros.

The raceway tanksweremaintainedwithnoexchangethroughoutthestudyandfresh-water was added to compensate for waterlosses.Oxygensupplementationwasinitiatedon Day 17 and continued until termination.The YSI 5500 monitors and their opticalprobesallowedtrouble-free,real-timeoxygen

supplementationwhile avoid-ing excess use.Concentrationsof total ammo-nia-nitrogenremainedbelow 0.5 mg/Lthroughout thestudy, whileNO2-N levelremained below1.22 mg/L withno significantdifferencesbetween treat-ments. While solids were controlled by theuse of the foam fractionators and settlingtanks,levelsoftotalsuspendedsolids,turbid-ityandvolatilesuspendedsolids levels intheSI treatment remained significantly higherthantheHItreatment.Theseresultsmayberelated to thehigher levelsof non-digestiblecomponents in the SI-35 feed fibre and ash.Oxygen use for the HI treatment was 21percentlowercomparedtotheSItreatmentand the volume of water used to produce1 kgof shrimpwas slightly lower for theHItreatmentthantheSI.

Analyses of shrimp performance basedon harvest data (see Table 4) showed nodifferences in survival rate, but better mean

finalweights,yields,growth,andFCRfortheshrimp fed with the HI-35 feed. This studyshowedthatmarket-sizeshrimpcanbepro-ducedwithnowaterexchange,andalthoughthe cost difference between the HI and SIfeedswassignificant($1.75/kgvs.$0.99/kg),apreliminary profitability analysis indicates thatbothfeedswouldbecommerciallyviablewiththeprofitadvantageinfavoroftheHIfeed.

The second trial lasted 63 days and wasconductedinthetwo100m3racewaytanksdescribed earlier. The tanks were initiallyfilled with a mixture of seawater, municipalchlorinatedfreshwater,andbiofloc-richwaterfromapreviousnursery study.Whereas thejuvenile shrimp (3.14 g) in the 2011 study

table 7. Summary of production and sales for the extrapolated commercial scale super-intensive biofloc dominated no exchange shrimp production operation, with 2011 trial results compared to three 2012 trials.

2011 HI-35 40 m3

SI-35 40 m3

HI-35 100 m3

Production, kg/crop 38,320 38,960 34,840 36,120

Crops per year 4.4 5.5 5.5 5.8

Production, kg/year 168,608 214,280 191,620 209,496

Production Mt/year 169 214 192 209

Selling price, $/kg 7.20 7.20 7.20 7.20

total Sales per year, $ 1,213,978 1,542,816 1,379,664 1,508,371

46 | InternatIonal AquAFeed | January-February 2014 January-February 2014 | InternatIonal AquAFeed | 47

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helpfultoolinincreasingthemoisturecontentallowedbytheminimumwateractivity.

Moreover, thewater isotherm andmois-turesampledatacanbeusedtocalculatethemoisture target and the upper control limit.Formost driedproducts, theportionof theisothermatandwellbelowthecriticalwateractivityvalueof0.65islinear,givingapropor-tionalrelationshipbetweenwateractivityandmoisture content. A simple linear equationcanthereforebeusedtodeterminethewateractivity value from the moisture content, orvice versa. The isotherm in Figure 1 showsthat amoisture contentof 8.92percentwillgiveawateractivityof0.65.Forthisproduct,then,8.9percentwouldbetheuppercontrollimit.

Sample varianceThe targetmoisture valuemust also take

intoaccountvariancebetweensamples.Here,the moisture sample history can be used tocalculate a standard deviation: ±3 standarddeviations from the averagewill account fornearly100percentofsamples.Themoisturetargetcanthenbecalculatedusingtheuppercontrol limit and the number of standarddeviationsrequired.

Targetmoisture=UCL–N(s.d.)UCL:UppercontrollimitN:No.ofstandarddeviationss.d.:Standarddeviationoftheproductsamples

To give an example, using a standarddeviationof0.6andtheaboveuppercontrollimit of 8.9 percent, and three standarddeviations,youwouldreceiveatargetmois-ture level of 7.12 percent. With currentdryer control methods, only 0.14 percentof moisture samples would have a chanceof exceeding the upper control limit. Manyusers of statistical process control methodswill use 2 or 2.5 standard deviations in thetargetmoisture calculation, giving targets of7.42 percent and 7.72 percent respectively(seeTable 2). The key values here are thepercentage of samples that may be statisti-callyabovetheupperlimit.

table 2: Resultsofalteringthenumberofstandarddeviationsontargetmoisturecalculation

target moisture UCl

number of

standard deviations

Standard deviation

% above UCl

7.12 8.92 3 0.6 0.14

7.42 8.92 2.5 0.6 0.62

7.72 8.92 2 0.6 2.28

With a method of calculating targetmoisturesanduppercontrollimitsinplace,we can give attention to optimising dryercontrol to reduce the moisture variance.

Asseenintheequationabove,areductionin the standard deviation will result in anincrease inthetargetmoisture.Theresultsofthisareincreasedproductionandenergysavings.

Assume, for example, that throughimproved dryer control the standard devia-tionwasreducedby30percent,to0.42(seeTable 3). The new target moisture wouldbe 7.66 percent, 0.54 percent higher thanthe previous figure of 7.12. As this shows,improveddryercontrol–obtainedbydryingwith cooler temperatures and being carefulnottoover-drytheproduct–canallowasafeincrease in average moisture levels, resultingina0.5percentproduction increase.Coolerdrying temperatures would also result inenergysavings.

table 3: Numberofstandarddeviationsvstargetmoisture,withimprovedstandarddeviationvalues

target moisture UCl

number of

standard deviations

Standard deviation

% above UCl

7.66 8.92 3 0.42 0.14

7.87 8.92 2.5 0.42 0.62

8.08 8.92 2 0.42 2.28

12 | InternatIonal AquAFeed | January-February 2014 January-February 2014 | InternatIonal AquAFeed | 13

FEATURE

A/S

wereofaTaura-Resistantstrainandstockedat390 juvenilesperm3, the shrimp (3.60g)used in the current studywere a crosspro-duced fromTaura-resistant andFast-Growthgenetic lines, stocked at a density of 500per m3. The shrimp were fed a HI-35 feedusing four 24-hour belt feeders for eachraceway.Thetanksweremaintainedwithnowater exchange and freshwater was addedweekly to maintain salinity and compensateforevaporative losses.Meanwater tempera-ture,salinity,dissolvedoxygen,andpHlevelswere 29.6 °C, 29.3 ppt, 5.5 mg/L, and 7.1respectively. Total ammonia nitrogen andNO2-Nremained lowthroughout thestudy,<0.6mg/Land<1.5mg/Lrespectively,whileNO3-N increased from67mg/L at stockingtoanaverageof309mg/Latharvest.ShrimpwereharvestedusingaMagicValleyHeli-Arcmechanical harvester. The study results aresummarizedinTable5.

Analysis: promising results point towards production refinements

Production of shrimp in indoor super-intensive recirculating systems can producelargequantitiesofshrimpbutcanhavehighini-tialinvestmentandoperatingcosts.Economicanalysesofthe2012trialsinthetwoproduc-tionsystemsusedbytheTexasA&Mmaricul-

turelabhavebeenveryencouraging.Productionresults for thebest trialrun in 2011 and thethree trial runs in 2012are presented in Table6. Using productionresultsandextrapolatingthem into the contextof a commercial facility,10-year cash flows andenterprisebudgetsweredeveloped to providecomparable financialindicators of profitabil-ity (cost of production,net return, net presentvalue, internal rate ofreturn, and paybackperiod).

For this hypothetical analysis one green-housesystemcontains10racewaytanks:eight500m3/m2 raceways for grow-out, and two500m3/m2racewaysforthenurseryphasetocultureten-day-oldpostlarvaetothe2.7gor3.6gjuvenileshrimpusedinoursimulations.Analysesincludeafixedcostcomponentcov-eringconstruction,equipmentandmachinerycostsofaround$992,000.Othercriticalpricesandcosts includeshrimpsellingprice($7.20/kg), feed cost ($1.75 and $0.99/kg), juvenileproductioncosts($20perthousand),andaninterestrateof8percentforoperating,equip-ment and construction loans. The economicquestionstobeansweredbythisanalysisare:

• Whether the production results arefinancially positive, given that one feedismuchmoreexpensivethantheotherfeed

• Whether progress was made betweenthe 2011 and 2012 trials in improvingtheprofitabilityofthesesuper-intensive,recirculating, biofloc shrimp productionsystems

Table 6 summarises the production andsales for the 2011 trial compared to 2012trials.

Table8summarisestheenterprisebudgetbased on 2011 and 2012 results, and indi-catesapositivenetreturnperkiloofshrimp

produced. The three 2012 trials had lowervariableproductioncoststhanthe2011trial’svariable cost. Likewise, the payback periodwas less for these same trials than for the2011trial.AllNPVsweretwotonearlythreetimesgreaterthanthe2011trial,andtheIRRforthe2012trialsweremuchhigherthantheROI for the2011 trial.Thus, theanswers tothe two economic questions posed earlier,are:• The more expensive HI-35 feed finan-

cially outperformed the lower-pricedSI-35inthe40m3and100m3trials

• The improvements on the 2011 trialsmadefor2012resultedinamuchbetterfinancialperformance

Now,theoldadage‘ifitlookstoogoodtobetrue, itprobably is’maybeatworkhere.Thehighlyfavourablefinancialresultsfromthe2012trialsneedtobeacceptedwithcareasacoupleofmajorassumptionsarebeingusedinthistypeofanalysis.First,themodelassumesthereisareadilyavailableyear-roundten-day-oldpostlarvae supply (whichmaybedifficultto achieve in the continentalUnited States),and secondly, research trials using these sys-tems have yet to actually conduct back-to-back-to-backproductioncycles.Waterre-useissuesshouldalsobetakenintoaccount(e.g.for how many production cycles the samewater can be used until complete replace-mentormajorpolishingisneededtomaintainbalancedioniccomposition).Also,theenergyusetoproduce1kgofshrimpineachsystemwillhavetobeevaluatedtodeterminewhichsystemismoreeconomicallyviable.

Although one research crop per year isan accomplishment, to actually produce 5.8cropsperyear(theresult for theHI-35100m3trial)withthesamehighlevelofoutputismuchmoredifficulttoachieve.Thesecaveatsarelargeandneedtobeaddressed.However,in the meantime the financial analyses con-ducted here using a tested bio-economicmodel,togetherwithcurrentpositiveresearchresults,canhelpresearchersfocustheireffortson the factorswhere improvementwillpro-videthemostreturn,helpingtosharpenthecompetitiveness of these intensive bioflocshrimpsystems.

table 8. Summary enterprise budgets for the super-intensive biofloc dominated no exchange shrimp production systems comparing the best 2011 trial with the three 2012 trials, in $/kg.

2011 HI-35 40 m3

SI-35 40 m3

HI-35 100 m3

Gross receipts 7.20 7.20 7.20 7.20

Variable Costs 5.38 4.06 4.54 4.31

Income above Variable Cost 1.82 3.14 2.66 2.89

Fixed Cost 0.59 0.47 0.53 0.48

total of all Specified expenses 5.97 4.53 5.07 4.79

net returns above all Costs 1.23 2.67 2.13 2.41

Payback period, years 2.9 1.4 1.9 1.6

net present value ($ mil.) 1.0 2.9 2.0 2.6

Internal rate of return (%) 31.3 66.6 50.1 60.6

48 | InternatIonal AquAFeed | January-February 2014

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