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Effects of soluble dietary cellulose on specific growth rate, survival and digestive enzyme activities in three

freshwater crayfish (Cherax) species

Redclaw (Cherax quadricarinatus)

Lalith Dammannagoda*Ana Pavasovicǂ

David Hurwood*Peter Mather*

*Science & Engineering FacultyǂHealth FacultyQueensland University of Tech.Brisbane, AUSTRALIA

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Cherax Endemic to Australia 3 Cherax species : Excellent candidates for commercial aquaculture

Redclaw (C. quadricarinatus) Yabby (C. destructor) Marron (C. tenuimanus)

Figure 1. Natural distribution of redclaw, yabby and marron (Wingfield, 2008)

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Cherax

Redclaw

Yabby Marron

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Crayfish aquaculture

Freshwater crayfish are an ideal aquacultural commodity

● Have excellent flavour and lobster-like appearance - high market value

● No larval stages - no need for expensive sophisticated hatcheries

● Omnivorous, opportunistic feeders - can be fed with inexpensive feeds

● More sustainable than prawn culture - no need for higher stocking densities / expensive coastal sites Female redclaws bearing eggs

and juveniles

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The largest operating cost (> 50%) of most fish and crustacean farming

Fish meal (FM) and fish oil Expensive Future availability ? (climate change / overexploitation)

Research priority Reduction of dependency on FM and fish oil inputs

Identification of alternative high-protein and low-cost feed ingredients

Feed optimization Require specific nutrient requirement identification Understanding of digestive enzyme activities of target species

Feed / Feeding

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Cellulose digestion/Endogenous cellulase ECE discovered in commercially cultured decapod crustaceans including

freshwater crayfish

ECE enables freshwater crayfish to breakdown complex polysaccharides (e.g. cellulose) and utilise plant-derived ingredients

endo β-1,4-glucanses

cellobiohyrolases

Cellobiose / cello-oligomers

Glucose

β-glucosidases

cellobiohyrolases Cellulose

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Crayfish growth studies

Previous growth and digestibility studies

Protein and lipid digestibility widely assessed

Less information on carbohydrates (types/amounts)

Effect / potential of soluble cellulose not investigated

C. destructor & C. tenuimanus less evaluated

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Objectives

Objectives

To investigate the effect of soluble dietary cellulose on growth performance and digestive enzyme activities in 3 Cherax species Growth performance: Feeding trial Enzyme activities: Enzyme assay

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(I) Feeding trial

Diets:

Reference diet (RD)

Test diet (TD)

n= 34

Feeding: 3% per day, twice

MethodsTable 1. Composition of experimental diets

Ingredient (gkg-1)

RD TD

Fish meal 581 581

Carboxymethyl cellulose

(CMC)

- 200

Corn starch 200 -

Fuller’s earth 79 79

Gluten 40 40

Gelatine 50 50

Vitamin/mineral pre-mix 25 25

Fish oil 25 25

Proximate composition % %

Dry matter 92.6 92.6

Crude protein 32.9 32.8

Ash 5.0 4.9

Gross energy 17.3 15.8

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(I) Feeding trial Culture: 12 wk independent trials

Table 2. Culture conditions maintained through out the experimental period

Outcome:

Analysis : Two-way ANOVA

Methods

Species Temp. / oC Cond./µscm-1 pH DO / ppm

Redclaw 26.0±0.01 517±4.0 7.9±0.01 7.42±0.05

Marron 20.4±0.03 499±1.0 7.9±0.01 8.67±0.02

Yabby 26.2±0.02 536±5.0 7.9±0.01 7.60±0.02

𝑆𝑢𝑟𝑣𝑖𝑣𝑎𝑙 𝑟𝑎𝑡𝑒= 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑛𝑖𝑚𝑎𝑙𝑠 𝑎𝑡 𝑒𝑛𝑑𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑛𝑖𝑚𝑎𝑙𝑠 𝑎𝑡 𝑏𝑒𝑔𝑖𝑛𝑛𝑖𝑛𝑔𝑋100

𝑆𝐺𝑅= 100 𝑋 𝑙𝑛 (𝑓𝑖𝑛𝑎𝑙 𝑏𝑜𝑑𝑦 𝑤𝑒𝑖𝑔ℎ𝑡/𝑔) – 𝑙𝑛 (𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑏𝑜𝑑𝑦 𝑤𝑒𝑖𝑔ℎ𝑡/𝑔)𝐷𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡 (𝑑𝑎𝑦𝑠)

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Methods

Aquaculture facility – QUT Pilot Plant Precinct, Banyo, QLD

Individual tank unit with cages

Specifications:

36 tanks / 27 L each Recirculating /purifying

system Automatic control of pH,

temp., CD at a set value Constant water exchange

rate at a desired value

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Methods

Methods

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(II) Enzyme assay

Enzymes assayed from the Hepatopancreas Protease Amylase Cellulase

Specific enzyme activity (enzyme units (U)per milligram of protein) was calculated

Methods

As described by Pavasovic et al. (2004)

Analysis: Independent “t” test

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Results(I) Feeding trial

Redclaw: SGR of (RD) significantly higher than (TD)

Lower survival rates observed in TD than in RD

Overall, females showed higher survival rates

[Significance level = p<0.05]

Species Diet SGRSurvival rate (%)

Female Male Total

RedclawRD 0.193±0.019a 100.0a 88.2a 94.1a

TD 0.093±0.019b 94.1a 64.7a 79.4a

MarronRD 0.146±0.019a 100.0a 94.1a 97.1a

TD 0.107±0.017a 88.2a 94.1a 91.2a

YabbyRD 0.105±0.018a 82.4a 100.0a 91.2a

TD 0.086±0.017a 100.0a 64.7b 82.4a

Table 3. SGR and Survival rate (%)

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Results

Table 3. Specific enzyme activity levels (±SEM) in the hepatopancreas.

(II) Enzyme assay

[Significance level = p<0.05]

Species Diet

Average specific enzyme activity (U/mg of protein)Protease Amylase Cellulase

AZO-Casein AZCL-HE-

CelluloseAZO-CM-Cellulose(X 10-3)

RedclawRD 2.469±0.18a 3.731±0.31a 3.408±0.20a 9.690±0.62a

TD 1.718±0.23b 2.257±0.30b 2.985±0.33a 7.338±1.12a

MarronRD 0.622±0.07a 0.168±0.02a 2.492±0.24a 5.535±0.54a

TD 0.315±0.04b 0.079±0.01b 1.540±0.16b 2.203±0.27b

YabbyRD 1.409±0.11a 2.753±0.21a 1.151±0.08a 4.372±0.38a

TD 0.930±0.13b 2.025±0.24b 0.861±0.09b 2.435±0.29b

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Conclusion/Future studies All three species responded in same direction for experimental diets

They appear to utilize starch more efficiently than soluble dietary cellulose

Inclusion of 20% soluble cellulose did not appear to have a significant negative effect on individual growth rate in yabby and marron

However, digestibility of soluble cellulose is needed to investigate

Further testing (lower levels) needed to evaluate potential of soluble cellulose to be used as a feed ingredient in commercial formulated diets

Results provide useful information towards formulating low cost crayfish diets for commercial aquaculture

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Acknowledgment

Supervisory team

Ridley Agri products, Australia

Crayfish suppliers Cherax Park, QLD Aquatic Resource Management Pty Ltd, WA Burns Yabby Farm / Reedy Creek Crays, NSW

Technical staff at QUT

Family & Friends

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