Seaweeds use as alternative nutrients in fish diets Cristóvão Nunes

1. Seaweeds use as alternative nutrients in fish diets Cristóvão Nunes Universidade de Trás-os-Montes e Alto Douro Ciência 2010

2. Aquaculture challenges Develop effective methods for greater: - Competitiveness - Productivity - Income Minimize environmental impacts Improve products quality Need for an integrated and multidisciplinary approach Sustainability of aquaculture systems

3. Aquaculture nutricion 24% of captured fish is for the production of fish meal and fish oil Fish feeding represents over 50% of operating costs in intensive aquaculture, Protein being the most expensive dietary source Searching for alternative protein sources for aquafeeds Plant protein sources - Deficiency in certain essential AAs - Palatability problems Algae are the natural plant source for fish!?

4. PTDC/MAR/105229/2008 Benefits of the production of Seaweeds in integrated multi trophic aquaculture (IMTA) Multidisciplinary research team with expertise in seaweeds physiology, seaweeds integrated farming and assessment of nutrient removal, chemical characterization techniques, fish nutrition, veterinary and microbiology

5. Project objectives • Create an alternative protein sources for fish-feed, that is both economic viable and have good quality • Improve the water quality in intensive systems • Promote fish health and improve fish flavor • Improve the image of farmed fish with the consumers, showing them that this activity can be environmental sustainable and produce high quality fish

6. Fish nutrition Concrete objectives Determination of the Apparent Digestibility Coefficient (ADC) of the diets with seaweed Determination of the growth performance of fish fed with seaweed-diets at different inclusion levels

7. Experimental ingredients Table 1 - Composition of test ingredients Produced in IMTA Captured The seaweed species will be initially selected based on its known productivity in culture, nutrient profiles and economical relevance

8. Experimental fish Rainbow trout (Oncorhynchus mykiss) Nile tilapia (Oreochromis niloticus) One of the most produced species in Portugal One of the most produced species in the world

9. Digestibility trials Methods Reference diet - 100% of the basal mixture Test diets - 70% of the basal mixture + 30% of each seaweed + chromic oxide (Cr2O3) Faeces were collected, using a specially constructed digestibility system according to the Choubert System The apparent digestibility coefficients (ADCs) of nutrients for the reference and test diets were calculated according to Maynard et al. (1979)

10. Digestibility trials Results tilapia Table 3 - Apparent digestibility coefficients (ADC %) of nutrients and energy of experimental diets and feed ingredients for juvenile tilapia

11. Digestibility trials Results trout Table 2 - Apparent digestibility coefficients (ADC %) of nutrients and energy of experimental diets and feed ingredients for juvenile trout

12. Growth trials Methods Reference diet - 100% of the basal mixture Test diets - 90% of the basal mixture + 10% of each seaweed Growth trials was carried out until fish triple their weight Three better digestible ingredients

13. Growth trials Results tilapia Table 4 - Growth performance, feed utilization and whole body composition in Nile tilapia fed diets with 10% seaweeds FI – Feed intake FCR – Specific growth rate FBW – Final body weith SGR – Specific growth rate

14. Growth trials Results tilapia Table 5 – Whole body composition

15. Growth trials Results trout In progress…

16. Preliminar conclusions In general, the apparent digestibility coefficients determined indicate that the seaweeds tested can be effectively digested both by the rainbow trout and the nile tilapia The growth of juvenile tilapia was not altered by replacing 10% of fish meal by seaweed meal (Ulva and Porphyra) Ulva and Porphyra seem the most interesting ingredients

17. Questions? You can adress to: Doutor Paulo Rema – UTAD prema@utad.pt Cristóvão Nunes cmnunes@utad.pt Thank you!