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Redclaw (Cherax quadricarinatus )

Effects of soluble dietary cellulose on specific growth rate, survival and digestive enzyme activities in three freshwater crayfish (Cherax) species. Lalith Dammannagoda * Ana Pavasovic ǂ David Hurwood * Peter Mather* *Science & Engineering Faculty ǂ Health Faculty

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Redclaw (Cherax quadricarinatus )

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  1. Effects of soluble dietary cellulose on specific growth rate, survival and digestive enzyme activities in three freshwater crayfish (Cherax) species LalithDammannagoda* Ana Pavasovicǂ David Hurwood* Peter Mather* *Science & Engineering Faculty ǂHealth Faculty Queensland University of Tech. Brisbane, AUSTRALIA Redclaw (Cherax quadricarinatus)

  2. 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)

  3. Cherax Redclaw Yabby Marron

  4. 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

  5. Feed / Feeding • 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

  6. Cellulose digestion/Endogenous cellulase endoβ-1,4-glucanses • ECEdiscovered in commercially cultured decapod crustaceans including freshwater crayfish • ECEenables freshwater crayfish to breakdown complex polysaccharides (e.g. cellulose) and utilise plant-derived ingredients Cellulose cellobiohyrolases cellobiohyrolases Cellobiose / cello-oligomers β-glucosidases Glucose

  7. 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. tenuimanusless evaluated

  8. 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

  9. Methods • (I) Feeding trial • Diets: • Reference diet (RD) • Test diet (TD) • n= 34 • Feeding: 3% per day, twice Table 1. Composition of experimental diets

  10. Methods • Feeding trial • Culture: 12 wk independent trials • Table 2. Culture conditions maintained through out the experimental period • Outcome: • Analysis : Two-way ANOVA

  11. Methods • 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 • Aquaculture facility – QUT Pilot Plant Precinct, Banyo, QLD • Individual tank unit with cages

  12. Methods

  13. Methods • (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 Pavasovicet al. (2004) • Analysis: Independent “t” test

  14. Results Feeding trial Table 3. SGR and Survival rate (%) [Significance level = p<0.05] • Redclaw: SGR of (RD) significantly higher than (TD) • Lower survival rates observed in TD than in RD • Overall, females showed higher survival rates

  15. Results (II) Enzyme assay Table 3. Specific enzyme activity levels (±SEM) in the hepatopancreas. [Significance level = p<0.05]

  16. 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

  17. 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

  18. ThankYou

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