DECAPSULATED ARTEMIA AS PL FEED
From: Laurence Evans Laurence@amatikulu.co.za
Sent: 22 June 2001
QUESTION:
I recently read
of the use of decapsulated Artemia cysts as a good (?) PL feed (unhatched).
Why is this application not widespread? What are the advantages/disadvantages. Cheaper Artemia can be used for
this, so it seems to me that this application should be standard practise?
Laurence Evans
e-mail : laurence@amatikulu.co.za
***************
COMMENTS 1 :
About 5 years
ago we tried to use decapsulated Artemia cysts of low grade hatching
Artemia, and we found that our survival in the LRT's was really bad; after
some research we found out that this product didn't have the same nutrient
value and about 5% of nutrient elements were missing, that is why we stopped
using it.
Eduardo Figueras
e-mail : efigueras@pecis.com
***************
COMMENTS 2 :
Certainly!
Especially considering the fact that hatching rates listed on products
by companies seem to be taken for granted and are not often verified!
Michael Haring
The Oceanic
Institute
Tel: (808) 329-9293
e-mail mharing@lava.net
***************
COMMENTS 3:
I have been
using decapsulated Artemia eggs as a feed for some years
now. This practice was stimulated by the lack of Artemia cysts and their
elevated cost in the past few years.
After some trial and error we now use these decapsulated cysts (which
are a byproduct of the hatching system and normally thrown away) between
days 8 (M3 - PL) and 14 of the 16 day cycle from N5 to PL 10. There are
however certain criteria that must be respected like feeding frequency,
quantities and most important the preparation and cleaning of the cysts
prior to feeding.
Andy Watkins
e-mail: andy@aqualider.com.br
***************
COMMENTS 4:
Decapsulation
is practiced at some or many hatcheries, because you get
higher hatch rates that way. And the shrimp can eat the unhatched ones as
well, since there is no hard shell left.
Some have noted there should be more energy content in Artemia nauplii from
decapsulated cysts (or in unhatched cysts as well), as they don't have to
spend it in cracking open the hard shell, only the soft membrane at most.
As noted in previous posting, if you use low-hatch cysts you may also be
getting low-value food, from missing nutrients, poor handling or storage,
etc.
Don't know if the unhatched Artemia from an otherwise decent
(non-decapsulated) batch are weaker / nutrient-deficient, or they just
happen to have a harder-than average shell. Maybe something in the
literature, have not seen it.
My bottom-line SWAG would be: Use decent-grade cysts, decapsulate, and feed
both hatched and unhatched critters.
Julio
Estrada
e-mail:
julioe@speed.net.ec
***************
COMMENTS 5 :
First of all I
would like to distinguish two different sources of
decapsulated cyst:
1 - hatchery decapsulated
2 - factory decapsulated
Hatchery Decapsulated
Often practised in South America, it can be for direct use to feed larvae
from low hatching eggs or remaining unhatched eggs from 24H Artemia cyst
incubation.
* Decapsulation may actually improve eclosion for some type of cyst if well
done; it is a good technique; but there are risks for direct feeding of
home-decapsulated cyst as remaining chemicals which are fairly repellent to
the larvae. Excellent neutralization and washing is a must !
* Non hatched - 24H incubated - decapsulated eggs have to be intensively
desinfected as they can make a great contamination method. Probably the eggs
taste better to the PL at this stage ! Most hatcheries have their trick to
clean them but I don't favour this practice.
* Most of these methods of decapsulation will be "mild" to
preserve the hatching capacity of the cyst/eggs.
Factory Decapsulated
* It is true there is more total energy in an unhatched egg than in a
nauplius (if you compare the same cyst of course). Their nutrient content
(vitamins, pigments, lipids...) differ too and the egg/embryo has all the
reserves in a stabilized form as to withstand years of dehydration and
dormancy.
* Factory decapsulated cyst - there are several commercial sources –
receive a different decapsulation process and have no purpose to hatch. They
will be over-decapsulated to dissolve the chorion and puncture the last
membranes around the embryo. Consecutive neutralization and drying will
remove all remaining chemicals and give it a stable shelf life. No need for
refrigerating/freezing.
* Are these cysts equal or worse than hatching ones ? I cannot say for all;
usually they will be processed out of low hatching grades - what doesn't
mean dead eggs !! - of low market value. The product I have dealt with were
as good or better nutritionally speaking than hatching eggs.
* Attractability is high with PL and broodstocks; dry decapsulated eggs will
hydrate almost instantly when put in contact with water and result to be a
very convenient food; as easy to use as a dry feed I would say.
For PL you would need to start from PL4-5 (vannamei/stylirostris) so they
can open the embryo membrane.
* Unlike nauplii decapsulated cysts don't swim and you have to split the
feeding in small quantities to avoid sedimentation and fouling.
My experience with commercial decapsulated cysts shows that it is equal or
better than Artemia nauplii in PL stages; you can make bigger/better fed
animals and at a lower cost considering the current Artemia market.
For some reasons, hatchery biologists still prefer live prey but it’s not
always better; shrimp will do with inert preys and currently there are a
number of other zooplankton alternatives, mostly dry or frozen, performing
as well and being much more convenient for storage, preparation or use.
Eric Pinon
Ex INVEman
e-mail : epinon@ecua.net.ec
***************
COMMENTS 6 :
Dried
non-hatching decapsulated cysts are available from INVE Aquaculture in
Mexico (inve-mexico@inve-mexico.com.mx),
Ecuador (inveecua@ecua.net.ec)
and the US (inve-us@inve-us.com).
INVE Aquaculture Inc.
e-mail: wtackaert@inve-us.com
***************
COMMENTS 7 :
As far as I
know most of the Artemia producers in the USA had processed an inventory of
decapsulated cyst not so long time ago. In Mexico I am not sure about who do
carry inventory of it in Mexico.
Currently I would suggest you contact INVE in the USA (inve-us@inve-us.com)
or Ravi Sangha their representative in Mexico
(inve-mexico@inve-mexico.com.mx)
because I know they had some product.
I would also suggest to give a call to David Mackay at Mackay Marine in Utah
Ph +1 801 261 1789 Fax +1 801 268 1193
I don't remember Salt Creek processing decapsulated cysts lately but you
always can get confirmation with them at Phone: 801-956-0662 Fax:
801-956-2868 sales@a-saltcrk.com
There are a few other Artemia harvesters but I don't think they have
processed any cysts for decapsulation.
Eric Pinon
e-mail: epinon@ecua.net.ec