The document discusses feed management strategies in shrimp farming, emphasizing the differences between intensive and extensive systems. It highlights a trial conducted that revealed lower feeding frequencies adversely affected growth rates and feed conversion ratios in shrimp. Additionally, it addresses the advancements in aquaculture netting systems that enhance environmental sustainability and profitability in fish farming.

1. November | December 2010
Feature title: Feed management in an intensive shrimp farming system with bioflocs
The International magazine for the aquaculture feed industry
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2. F
eed management in exten-
sive and semi-intensive
shrimp farming systems
differs a lot with the feed
management, which is practiced for
fish farming.
Feeding frequency is limited
to four or six times per day.
The feed is spread over the whole
pond, which is labor-intensive. There are
also some indications that lower feeding
frequencies are not affecting growth. The
reason is most probably the availability of
natural feeds in the pond, which comple-
ment the shrimp nutrition in the absence of
feed (between feedings).
The lower the feed quality the better it
will be to decrease the feeding frequency,
because it forces the shrimp to go for
natural feed, which has a better quality than
the feed.
In the continuous presence of low qual-
ity feeds,the shrimp will fill its stomach with
this feed with slower growth as a result.
Intensive farming
with bioflocs
However, the feeding affects the water
quality parameters in the ponds.An oxygen
drop is observed after feeding.
A continuous feeding will result in a more
continuous water quality and less stress for the
shrimp.In intensive farming,the natural produc-
tion of the tank is represented by bioflocs.
These bioflocs
directly interfere
with the water
quality. Intensive
farming also allows
the mechanization
of feeding without
extra labour.
Trial
The influence of
feeding frequency on
growth and FCR was
observed in the AFT-
CreveTec Research
station in Venray,
Netherlands.
Four different diets with crude protein
content of 38 percent and lipid content of
eight percent were formulated and pro-
duced with a pellet press at two mm.
Shrimp (Litopeneaus vannamei) were
imported from Thailand and raised till six
grams. They were divided over 20 nets,
which resulted in 23 per net. They were
weighed individually at start and finish.
Feed management
in an intensive shrimp farming system with bioflocs
Table 1: Average growth and FCR
Feeding regime
Growth
(g/week)
FCr
Week 1 continue 1,67 1,46
Week 2 continue 1,74 1,03
Week 3 4 times/day 1,38 2,62
Week 4 4 times/day 1,14 3,75
Week 5 2 times/day 0,83 2,58
Week 6 2 times/day 0,99 4,59
by Eric De Muylder of CreveTec, Belgium and Leon Claessens of Aquaculture Farming Technology, The Netherlands
38 | InternatIonal AquAFeed | november-December 2010
Feed Management
november-December 2010 | InternatIonal AquAFeed | 39
Every week, total weight and number
was measured to have average weights.
During the first two weeks, the shrimp
were fed on a continuous basis. During
week three and four, they were fed four
times per day. During week five and six, they
were fed only two times per day.
The average growth and FCR can be
seen in table 1
It is clear that the reduction in feeding
frequency affected the growth negatively.
The shrimp were also not able to con-
sume all the feeds, which resulted in much
higher conversion ratios.
More inforMation:
Eric De Muylder
CreveTec
Belgium
Email: eric@crevetec.be
Leon Claessens
Aquaculture Farming Technology
The Netherlands
Email: info@aquaculture-ft.com
38 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 39
Feed Management
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adv_aqua2011_210x147_aV2.indd 1 17-09-10 15:49
A
fter researching a wide
array of cage netting to
farm their tilapia in,Trapia
Malaysia Sdn Bhd selected the
Aquagrid® Containment System
because - it met and exceeded
their operational objectives for
net strength and resistance to
bio-fouling.
Headquartered in Ipoh in the
State of Perak, Malaysia, their
eco-friendly farm operates in the
pristine rainforest-fed, freshwater
lakes of Tasik Temenggor of the
Perak River system.
Trapia's management sought
to protect this unique grow-out
environment by searching for
a cage system that would keep
their tilapia in and the preda-
tors out while ensuring profit-
ability and minimising environ-
mental impacts. Tilapias have the
annoying habit of grazing on cage
netting, damaging the fibres of tra-
ditional netting but the coating
on the Aquagrid® containment
system prevents this from hap-
pening.
In addition, to escape- and pred-
ator-proof netting, Trapia also
required netting that was more
resistant to bio-fouling and would
last longer than traditional mate-
rials used for aquaculture, such
as nylon.
Aquagrid® netting's semirigid,
PVC coated polyester material and
special design makes it up to 100
percent stronger than nylon or poly-
ester and eliminates the use of anti-
fouling products which can leach
into the surrounding water.
The Aquagrid® contain-
ment system's LiftUP® Mortality
Retrieval System, designed to fit
the special conical bottoms of the
Aquagrid® cages, collects mortal-
ities, unconverted feed and feces
and pumps them to the surface for
disposal, ensuring the watersTrapia
operates in are kept clean and safe
for future generations of fish.
Trapia COOAlejandroTola is very
impressed with the performance of
the Aquagrid® cages since their
installation in November 2008.
"The nets are very easy to
clean by simple brushing and the
strength of the material is definitely
keeping away and avoiding break-
ins from carnivorous species in the
lake.The logistics consequences of
this are huge," he says.
More inforMation:
TenCate Industrial Fabrics
365 South Holland Drive
Pendergrass, Georgia 30567
USA
Tel: +1 706 6932226
Fax: +1 706 6934400
Website: www.aquagrid.com
Trapia Malaysia selects TenCate Aquagrid® containment system
to ensure profitability while protecting the environment
6 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 7
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Salmon Farmers Association is
eager to be part of a larger dis-
cussion about what the real issues
are.
"We have seen large variations
in wild salmon populations as
our farm operations remain the
same," says Mary Ellen Walling,
Executive Director of the BC
Salmon Farmers Association.
“For example - there was no
significant difference in opera-
tions between the poor Sockeye
return of 2009 and the trium-
phant return in 2010.
"That tells us that more needs
to be considered as we talk about
standing for the Cohen
Commission Inquiry into the
decline of Fraser River Sockeye
Salmon.Along with groups repre-
senting a wide range of interests,
they will be participating in the
evidentiary hearings beginning
October 25, 2010 to share infor-
mation about their operations
and research, as well as correct
erroneous claims.
The message from anti-
salmon farm activists during a
recent campaign oversimplifies a
complex situation. It ignores any
effects rising water temperatures,
failed plankton blooms, extraordi-
the life-cycle of BC's salmon. All
of these items are on the list of
things Justice Bruce Cohen will be
investigating.
In the meantime, BC's salmon
farmers continue to grow a
healthy product in a sustain-
able way, while leading the way
in research and development
and working with environmental
groups and the community to
find answers to industry ques-
tions.
"Salmon farming is a highly-reg-
ulated industry that is continually
improving," adds Ms Walling.
"We believe that our well-
employs roughly 6,000 people
directly and indirectly, contrib-
uting US$800-million to the pro-
vincial economy. Farmed salmon
is the province's largest agricul-
tural export.
More inforMation:
Mary Ellen Walling
Executive Director
British Columbia Salmon Farmers
Association
#302 - 871 Island Highway
Campbell River, BC V9W 2C2, Canada
Tel: +1 250 2861636 x223
Fax: +1 250 2861574
Email: mwalling@salmonfarmers.org
Website: www.salmonfarmers.org
4 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 5
ONLINE ARCHIVE
Our readers can find an archive of back issue's on the
aquafeed website. We also make individual features
available to view and download
www.aquafeed.co.uk/archive.php

3. FOR FISHMEAL REPLACEMENT
Functional Hydrolysates for Aqua Feed
Contact us at : +33 2 97 93 89 36
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AP-TEASING_87x267.indd 1 16/08/10 16:44
r t
of
o
ut
ls
st
ic
g,
es
ts
d
e
o
or
n
e
h
w
al
nt
s.
is
rs
| InternatIonal AquAFeed | 9
larval and juvenile post -larval stages before
reaching the mature or adult phase. The
length of the culture period varies but
for Pacific white shrimp it can take about
20 days for the larvae to metamorphose
to post larvae and approximately another
three to four months to reach market size
in tropical waters at 25-27°C.
The rate of growth of the shrimp is a
function of the frequency of molting and the
increase in size at each molt.
However, the frequency of molting
decreases as the shrimp increases in weight
with the intermolt period increasing in
length. In the 20 day larval period, from egg
to post-larvae, there can be 16-20 molts,
a further 20 molts in the 40 day nursery
phase to approximately 2g and an additional
eight molts in the final 80 day grow out
phase to 20g.
The diet quality during the exponential
nursery growth period, from approxi-
mately 0.5mg to 2.0g, with high molting
frequency, is especially critical as it is dur-
ing this period that the final yield potential
is laid down.
Lipids, such as phospholipids, triglycer-
ides and cholesterol, are a major source
of energy in shrimp diets as well as being
involved in several essential processes for
their growth, molting and reproduction.
Cholesterol is an essential dietary nutri-
ent, for members of the crustacean family,
as they are incapable of synthesising their
own cholesterol from fatty acids unlike
other animals.
Cholesterol is an essential component of
all animal tissues, it plays a major role in cell
membrane structure, is a precursor for sex
hormones, for bile acids and for vitamin D.
In crustaceans cholesterol is a precursor
for many hormones, including ecdysteroids,
which are critical for the initiation of meta-
morphosis and the
moulting process
(Teshima, 1997).
Cholesterol
availability
In their natural
habitat shrimps will
obtain naturally
occurring sterols
from algae and
zooplankton, how-
ever these sources
will not be avail-
able to shrimp in
semi-intensive or
intensive cultiva-
tion in the required
amount.
In commercial
diets cholesterol
is a natural com-
ponent of marine
invertebrate meals
and oils, for exam-
ple from squid,
shrimp, clams and
crab. However the
cholesterol content
of these ingredients
varies considerably
and is present in
a less esterified
form requiring
more energy for
its utilisation than
it manufactured
alternative.
The industry
requirement for
guaranteed quality
characteristics with
higher bioavail-
Figure 1: Effect of 3 cholesterol levels on the
growth and survival of Litopenaeus vannamei
bred in ponds ( Ir A.H.Mogollon and Ir. V.V. Rubin,
University of Tumbes, Peru)
november-December 2010 | InternatIonal AquAFeed | 31
F: Shrimp farming
Rising feed
cost
Escalating
fish meal price
Opportunistic
diseases
Environmental
impact
Low Shrimp
& fish prices
Feed is the main cost
in most aquaculture
operations …
and the most difficult one
to reduce when ingredient
prices are rising …
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applying nature for a healthy and sustainable future
2 | InternatIonal AquAFeed | november-December 2010
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4. www.aquafeed.co.uk
LINKS
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Volume 13 Issue 6 2010
the international magazine for the aquaculture feed industry
Seaweeds as Ingredients
in Aquatic Feeds
A new and revolutionary type
of feather meal for fish feed
New dimension in the production
of hygienized feed meal
Chromium
- the forgotten mineral that plays an essential
role in the utilization
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