tilapia production in biofloc systems yoram avnimelech tecnion, israel inst. of technology...
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TILAPIA PRODUCTION IN
BIOFLOC SYSTEMS
YORAM AVNIMELECH
TECNION, ISRAEL INST. Of TECHNOLOGY
» » Biofloc technology is based upon a few principles: » (a) Zero or minimal water exchange, » (b) subsequent development of dense microbial population » (c) managing the microbial population as a part of the pond
eco-system » (d) adjustment of the C/N ratio to 15 in order to control
inorganic nitrogen concentration in the water.» The bacteria, forming bioflocs, assimilate TAN, produce
microbial proteins that is consumed by the fish, thus recycle the unused feed protein. (For more details: Yoram Avnimelech, Biofloc Technology, A Practical Handbook, World Aquaculture Soc. 2012).
Tilapia, an ideal fish for Biofloc Technology
Grow well in dense cultures
•Resistant•FILTER FEEDER
•Very few studies as compared with shrimp
Fish BiomassNormally, 20-30 kg/m2
10 times higher than shrimp BFT ponds!
Implications:
» High Biomass 20-30 kg/m3 (Up to more than 40kg/m3 » (w/o O2)» High feeding (ca 500 g feed/m3 per day)» Very high microbial activity» High floc volume (20-50 ml/l). » Very high natural feed storage. » High levels of feed residues » Need to drain out daily (or twice daily) excessive sludge.» Pond constructed to facilitate sludge draining and perfect mixing.» High and effective aeration: 10-20 hp/1000 m2 pond
Drain bottom sludge twice daily till you get clear water
» Bio flocs are made of bacteria, protozoa, feed residues etc.
» Bioflocs size may reachA few mm diameter» Effectively harvestedby tilapia
x20x10
x10 x10
200 µm
200 µm 200 µm
Bio flocs are made of bacteria, protozoa, etc. Typicaly their diameter is 0.1-2 mm.
Protein Recycling
» Normally, fish or shrimp recover just ~25% of feed protein.
» In bacterial controlled ponds, they eat the protein twice; Once in the feed and then they consume microbial protein. The protein recovery reaches almost 50%.
» Protein is the most expensive part of the feed.
BFT control Expt. # 1
51 days
16.6 11.1 FEED C/N
2.0b 1.59a Daily Gain)%( 2.17 2.62 FCR2.42 4.38 PCR
0.583 0.848 FEED COST )US$/Kg fish(
Exp. # 2 )30 days(
16.6 11.1 C/N2.22b 1.63a Daily gain)%( 2.02 2.62 FCR2.18 4.35 PCR
0.543 0.848 Feed cost(US$/Kg fish)
Results 1: % 15N in fish % 15 N in fish
0.3000
0.3500
0.4000
0.4500
0.5000
0.5500
1 3 5 7 9 11 13 15
Days
% 1
5N
Residence time of bioflocs
» Bioflocs were taken up by fish and degraded biologically. Yet, the amount of bioflocs stayed almost constant. This implies that new flocs are constantly produced (using the excreted N).
» The residence time of bioflocs was calculated to be around 8 hours. The flocs seem to be a very dynamic system.
» most cells in the flocs are young and active.
Data on feed protein utilization
» Conventional fish, shrimp ponds 20-25%» BFT Tilapia ponds (Avnimelech) 45%» BFT Shrimp ponds (McIntosh) 45%» Closed shrimp tanks (Velasco) 63%
» BFT shrimp ponds, 15N study 18-29% of total N consumption (Michele Burford et al.)
* Tilapia, 15N Study, flocs supplied about 50% of fish protein requirement. (Avnimelech).
Feed Utilization
» Fish or shrimp growing in BFT systems eat the pellets when applied, but eat bioflocs all the time.
» Confirmed in a work done by Albert Tacon with shrimp.
» Observations with tilapia.» Effects on lowering of FCR in tilapia production
SPECIAL USES, ADDED VALUES
DESERT AQUACULTURE
Effects on propagation
Shrimp broodstock grown in BFT have earlier sexual maturityAnd higher productivitySimilar result with tilapiaWork by Julie Ekasari
Better nutrition? Fatty acids?Hormonal effects?
Summary of fatty acids analysis on the collected bioflocs
Fatty acids %Total Fatty AcidsTotal n-3 1.33Total n-6 19.70Total n-9 12.97
LA 13.43ALA 0.36EPA 0.56DHA 0.32AA 1.30
n-6 fatty acids is essential for tilapia
and its reproduction (Watanabe 1982)
•Biofloc considerably high in AA (Arachidonic Acid)•AA is beneficial for fertilization rates stimulates testicular
testosterone in goldfish (Izquierdo et al 2001)
Protein : 37 – 46% DWLipid : 11.9 % DW
2 .Physiological factors˃Hormones˃Morphological changes˃Mobilization of energy reserves
•Blood total cholesterol in fish in BFT tanks was higher
Cholesterol precursor of steroids hormones
•Blood glucose as an indicator of mobilization of energy
reserves
•Fish growth
What triggers the fish to spawn? (Rocha 2008)
Results: Blood total cholesterol
•Higher concentration in BFT higher concentration of hormones were
involved?
Results: Blood glucose
•Higher concentration in BFT
•More energy was mobilized for reproductive activities
•More energy supply?
Results: Average body weightDespite of more active reproductive performance the female in BFT tanks
grew better
Yet, the fish in BFT required less feed
(9.3 vs 8.3 kg/tank)
a b
Results : Total fish fry production
Julie Eskari
Fresh results from the field:
» Tilapia fingerlings (120 g) stocked to over-wintering facility on January 4, 2011.
» Feeding ~ 1% BW» On February 18, they weighed 171 g» Daily growth of 1.16 g/fish» FCR = 0.5
OVER-WINTERING
AND SECONDARY INFECTION OF FISH BY STREPTOCOCCUSTotal infected Sick fish Dead fish Treatment
a)Injected fish
11 2( 2) 9( 9) Control
16 4( 2) 12 (3)
BFT
a)Non-injected fish
11 (4.7)
4( 1.5) 7( 5) High exchange
3 (1.4)
1.3( 1.0) 1.8 (1.7)
ASP
High water exchange = 0.5l/min per kg fish (700% per day) BFT< Limited water exchange = 10% per day
EFFECT OF WATER EXCHANGE RATE ON PRIMARY
Control
Control
BFT
BFT
Luo and coworkers in China reportedYields of 45kg/m3. Higher production and lower FCR as compared with RAS. Higher concentrations of SuperoxidePermutase .
»Conclusions» Biofloc technology is especially adapted to raise tilapia
production up to 20-30 kg/m2.» This can be done using not too expensive system.» BFT enables feed recycling, high feed quality and reduced
expenses.» BFT reduces disease.» The system is friendly and forgiving.» More research is needed
» Cultivo de tilapia en sistemas biofloc es simple, fácil y rentable. • Tilapia como filtrador es feliz en esos sistemas. • Se ahorra los gastos de alimentación (~ 30%) y comer mejor. • Menos enfermedades. • Mayor crecimiento y menor FCR. • La manera más rápida de iniciar la producción intensiva de tilapia. • Si necesita ayuda, estaré feliz de hacerlo: