soft-shell
problem in Penaeus broodstock
From:
Mueller Olivier omueller@fastnet.ch
To: shrimp@yahoogroups.com
Sent: 8 November 2004
question:
We
are running actually in Vietnam an experiment to create a stock of
domesticated P. monodon
breeders using a recirculating system. We actually encounter
mortality problem because shrimps are suffering from soft-shell.
Do you have some info
concerning this problem or any idea about the reason of
this problem?
e-mail: omueller@fastnet.ch
***************
COMMENTS
1:
There can be different reasons for the mortality, but basically,
the problem is that the shrimp don't complete the moulting process because
of a nutritional imbalance. Very often, this imbalance is caused by an
environmental factor (high pH soil, very low salinity, or high salinity,
hardness) causing some minerals to be less available to the shrimp, such as
phosphates. This can be compensated by feeding with high quality feed, which
you should do anyway if you want to get any results with your domesticated
broodstock.
We are feeding our broodstock with a special diet, and have never
experienced this problem.
So I have the following questions:
What is the salinity of your water ? And are the minerals balanced (the same
proportions as in sea water )?
Which kind of feed do you give them ? Commercial growout pellets or a
special formula for broodstock ? Do you know the macro mineral content of
the feed ? And the cholesterol and phospholipid content ?
Eric De Muylder
VDS Crustocean Feeds
VDS bvba
Paanderstraat 40
8540 Deerlijk
Belgium
Phone (VDS): +32 56 719168
Phone (direct): +32 56 723012
Fax: +32 56 723002
Phone (mobile): +32 496 543021
E-mail: eric@vds-afs.be
Web: www.vds-afs.be
Web: www.crustocean.com
***************
COMMENTS 2:
Soft shell is a very poor nutrition sign. I recommend a
better nutrition and use the Growth Factor into your pellets.
e-mail: buenbarro@hotmail.com
***************
COMMENTS 3 :
Thanks for the valuable information which confirms my impression.
The salinity is between 33 and 35 %o and the water come directly from the
sea after treatments (sand filtration, UV and ozonation). The shrimps are
fed with commercial feed.
The feed quality is probably the main problem and I will try a home made
formulation with fresh ingredients as mussels and squid. Do you have a
personal formulation to recommend?
Do you have any idea if the ozonation of water can have an incidence?
Olivier Mueller
e-mail: omueller@fastnet.ch
***************
COMMENTS
4:
I fear that making on farm feeds would not solve your problem,
because poor water stability of the home-made pellets could even worsen the
problem.
If you have access to fresh squid and mussels, I think it is a better idea
to replace one feeding per day of the commercial feed by the fresh feed.
Eric De Muylder
E-mail: eric@vds-afs.be
You
should describe a little bit the type of recirculation system that you are using. What kind
of machinery for filtration, and how much water exchange you do (if any at
all)? This information may help in figuring out what your problem is.
e-mail:
toddblacher1@yahoo.com
***************
COMMENTS 6:
We have actually 2 tanks of 20 m3 but we will enlarge the project
up to 20 tanks. Each tank is equipped with an ozoniser, a biofilter and a
system of water injection under a sand layer at the bottom of tank where
shrimps like to stay. 10 % of water is renewed every day and the
recirculation rate is approximately 10 to 20 % per hour.
Olivier Mueller
e-mail: omueller@fastnet.ch
***************
COMMENTS
7:
I have been contacted by a feed manufacturer in Vietnam and will
try to establish a better diet. Anyway we will add fresh feed probably
mussels.
I found this formulation in a publication which seems to give good results
that I will try:
Ingredients
g/ 100g
Squid
41
Minced mussels
22
Calf liver
11
Artemia enrichment Selco dry *
4
Milled mollusk shell
2
Lecithin
3
Vitamin mix
5
Mineral mix
3
Cholesterol
1.1
Astaxanthin
4*10-3
B-carotene
4*10-3
Binder alginate
10
Olivier Mueller
e-mail: omueller@fastnet.ch
***************
COMMENTS
8:
Fresh food items are often ingested preferentially over dry
artificial
feeds by wild spawners. The recipe you mention - by Marsden et al. -
has the one advantage that you can mix fresh food items with dry
ingredients, hence ensuring the uptake of essential nutrients lacking in
fresh food. This recipe has been proven to be suitable for P. monodon
(while most research has been done on white shrimp). If you are
concerned about water stability of moist diets or if you prefer to work
with balanced dry diets, feel free to contact me off-list for test
results and technical information on INVE Breed-Shrimp Concentrate or
Breed-S pellets.
You can also contact INVE's office in Ho Chi Minh for similar info on
broodstock diets or Selco products: INVE (THAILAND) Ltd. Vietnam Rep.
Office, 3 T Ton Duc Thang, District 1, Ho Chi Minh City, VIETNAM; +84
8 822 34 94 , +84 8 829 32 53 ,
invevietnam@iviet.com.vn
Roeland WOUTERS, Ph.D.
Larval Shellfish Nutrition
INVE Technologies N.V.
Hoogveld 93
B-9200 Dendermonde
BELGIUM
Tel.: +32-(0)52-40.95.95
Fax.: +32-(0)52-40.95.85
e-mail: r.wouters@inve.be
website: www.inve.com