Transcript Slide 1

TILAPIA PRODUCTION IN
BIOFLOC SYSTEMS
YORAM AVNIMELECH
TECNION, ISRAEL INST. Of TECHNOLOGY
[email protected]
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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).
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Grow well in dense
cultures
Resistant •
FILTER FEEDER •
Very few studies as •
compared with
shrimp
Normally, 20-30 kg/m2
10 times higher than shrimp BFT ponds!
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
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» Bio flocs are made of bacteria, protozoa, feed
residues etc.
» Bioflocs size may reach
A few mm diameter
» Effectively harvested
by tilapia
200 µm
200 µm
x10
x10
x20
200 µm
x10
Bio flocs are made of bacteria,
protozoa, etc. Typicaly their
diameter is 0.1-2 mm.
» 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.
Expt. # 1
control
BFT
FEED C/N
11.1
16.6
Daily Gain (%)
FCR
PCR
FEED COST (US$/Kg fish)
1.59a
2.0b
2.62
2.17
4.38
2.42
0.848
0.583
C/N
11.1
16.6
Daily gain (%)
1.63a
2.22b
FCR
2.62
2.02
PCR
4.35
2.18
51 days
Exp. # 2
(30 days)
Feed cost
(US$/Kg fish)
0.848
0.543
% 15 N in fish
0.5500
% 15N
0.5000
0.4500
0.4000
0.3500
0.3000
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3
5
7
9
Days
11
13
15
» 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.
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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).
» 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 maturity
And higher productivity
Similar result with tilapia
Work by Julie Ekasari
Better nutrition? Fatty acids?
Hormonal effects?
Fatty acids
% Total Fatty Acids
Total n-3
1.33
Total n-6
19.70
Total n-9
12.97
LA
13.43
ALA
0.36
EPA
0.56
DHA
0.32
AA
1.30
n-6 fatty acids is
essential for tilapia
and its reproduction
(Watanabe 1982)
Protein : 37 – 46% DW
Lipid : 11.9 % DW
Biofloc considerably high in AA (Arachidonic Acid) •
AA is beneficial for fertilization rates  stimulates testicular
testosterone in goldfish (Izquierdo et al 2001)
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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 •
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Higher concentration in
BFT  higher
concentration of
hormones were
involved?
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Higher concentration in
BFT 
More energy was •
mobilized for
reproductive
activities
More energy supply? •
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Despite 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
Julie Eskari
b
» Tilapia fingerlings (120 g) stocked to overwintering 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
EFFECT OF WATER EXCHANGE RATE ON PRIMARY
AND SECONDARY INFECTION OF FISH BY STREPTOCOCCUS
Treatment
Dead fish
Sick fish
Total infected
Control
Control
a)Injected
fish
a)Noninjected
fish
BFT
BFT
High
Control
exchange
BFT
ASP
9 (9)
2 (2)
12 (3)
4
(2)
4
(1.5)
11
(4.7)
1.3 (1.0)
3
(1.4)
7
(5)
1.8
(1.7)
11
16
High water exchange = 0.5l/min per kg fish (700% per day)
BFT< Limited water exchange = 10% per day
Luo and coworkers in China reported
Yields of 45kg/m3. Higher production and
lower FCR as compared with RAS.
Higher concentrations of Superoxide
Permutase .
» 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:
» [email protected]