The nutritional quality of larvae diets affects fishes’ fillet quality and quantity. Studies show that phospholipids increase fish larvae growth and development; so phospholipids are an essential component of the early weaning diet.

1. T
he nutritional quality of larvae diets
affects fishes’ fillet quality and quantity.
Studies show that phospholipids
increase fish larvae growth and
development; so phospholipids are
an essential component of the early
weaning diet.
During embryo and larval
development, yolk sac lipids or wild
prey provide young fish with ample amount of phospholipids.
In fish larvae diets, the aim is to provide larvae nutrition and an
effective diet that substitutes live prey as early as possible during
the larval development.
Scientists have studied the effectiveness of phospholipids
including those derived from soybean lecithin and dietary
marine phospholipids from krill. Krill phospholipids, rich on
docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), have
a positive effect on larvae performance and development, which
makes a difference later to filet quality and quantity.
Phospholipids: a core component to larvae development
Studies have shown that dietary phospholipids improve culture
performance, enhance growth and increase the survival of various
freshwater and marine species including ayu (Plecoglossus
altivelis), carp (Cyprinus carpio), Japanese flounder (Paralichthys
olivaceous), knife jaw (Oplegnatus fasciatus) and red seabream
(Pagrus major). Phospholipids also reduce incidents of skeletal
deformities in larvae and early juveniles, and increases fish
resistance to stress.
Phospholipids are the main structural component of cell
membranes, tissues and are vital organ development. They especially
play a vital role in the development of organs including the digestive
system. Dietary phospholipids play a contributing role to the
assimilation of dietary lipids; increase the efficiency of transporting
dietary fatty acids and lipid from the gut to the rest of the body.
So adding phospholipids to larval diets has unique benefits to the
development of larvae, juveniles and fishes later in life.
Efficient and effective krill phospholipids
Phospholipids include a large group of compounds, and the lipid
classes as well as the fatty acid content determine their effectiveness.
Studies show that dietary marine phospholipids, in comparison to
soybean lecithin, improve culture performance. Three recent studies
indicate the different benefits of this form of phospholipid.
In the first study, scientists compared the effect of krill
phospholipid to soybean lecithin in micro diets for gilthead
seabream larvae on molecular markers of antioxidative
metabolism and bone development. The results from the studies
show that marine phospholipids have a higher effectiveness
in promoting survival, growth and skeletal mineralization of
gilthead seabream larvae in comparison with soybean lecithin,
regardless of the dietary phospholipid level (R.Saleh, M.B.
Betancor, J.Roo, V. Benitez-Dorta, M. J. Zamorano, J.G. Bell and
M. Izquierdo, 2014).
The study was conducted as follows. Scientists fed larvae, from
16 to 44 days post hatching, three levels of phospholipids from
marine phospholipid and soybean lecithin (50, 70 and 90 g kg-1).
The increase of up to 70 g kg-1 marine phospholipid was enough
to see and improve larval gilthead seabream performance and
even the highest level of soybean lecithin (90 g kg-1) was unable
to provide similar successful results.
However, larvae that were fed diets without phospholipid
supplements, also known as the control diet, showed a very low
survival rate. This indicates that phospholipids are an essential
competent of the natal diet.
Despite increasing soybean lecithin up to 90 g kg-1 to
improve larval survival, stress resistance, growth and skeletal
development, the results showed that dietary marine phospholipid
was more effective in promoting these parameters. Krill
phospholipids’ higher content in PC, LPC, ARA, antioxidants
factors such as carotenoids (astaxanthin) eicosapentaenoic acid
(EPA), and docosahexaenoic acid (DHA), promotes digestion,
transport and deposition of dietary lipids, and contributes to
reduce skeletal anomalies.
The study also showed that krill phospholipids affect skeleton
malfunction, bone mineralization, biochemical composition,
oxidative status and selected genes expression.
Just like the results from other studies, by increasing marine
phospholipids in species such as Atlantic cod (Gadus morhua)
and European sea bass (D. labrax), larvae growth increases.
Phospholipids that make
a difference to filet
quality and quantity
KRILL OIL
24 | March | April 2016 - International Aquafeed
FEATURE

2. Marine phospholipids appear to be a superior component to
enhancing larvae growth and development, compared to when
phospholipids are incorporated in micro diets through soybean
lecithin.
In a second study (R. Saleh, M.B. Betancor, J. Roo, T. Benitez-
Santana, M. J. Zamorano and M. Izquierdo, 2013) phospholipids
derived from krill improved larval growth and survival more
effectively than soybean phospholipids. Krill phospholipids
enhanced n-3 HUFA and incorporated EPA incorporation into
larval tissues.
A significant correlation was found between length and final
weight, and phospholipids in the diet. Sea bream larvae that
were fed diets without phospholipid supplements showed the
lowest survival, growth, and stress resistance.
Increasing the dietary phospholipid content improved stress
resistance determined as survival after handling, regardless
of whether the phospholipid was derived from marine or
soybean. Feeding sea bream larvae with krill phospholipids
particularly improved total length and body weight.
This is because krill phospholipids contain higher n-3 HUFA
and DHA levels than soybean lecithin.
Optimal diet with krill phospholipids
The third study recently conducted on the benefits of krill
phospholipids, looked at the the optimum dietary levels of krill
phospholipids for Sea bream (Sparus aurata) larvae, its influence on
larval development and digestive enzymes activity.All increases of
dietary krill phospholipids up to 120 g kg-1 significantly improved
larval survival, growth and digestive enzyme activity. Further
increase did not improve those parameters.
Krill phospholipids are also attractants
In addition to fish larvae diet being nutritious and including
beneficial components to larvae growth and health, the initial
diet needs to be attractive. It needs to be the right size to fit
into the larvae’s mouth and taste good. Krill phospholipids
have shown to be an attractant, not only attracting larvae to
the consumption of feed with krill phospholipids but also
increasing the amount of food consumed.
Krill phospholipids have nutritional benefits that stand out
from phospholipids derived from other sources. Today krill
phospholipids in krill oil are a crucial component of krill meal.
Work is also being conducted to extract this oil and make it into
a separate product; given its distinct features and benefits to the
larvae, juvenile fish and fish farmer given the improved filet
quality and quantity.
visit us at seafood expo Global
26 - 28 April 2016, Brussels, Belgium
Booth 4026 in Hall 9
GlobalG.a.p. News Conference
27 April 2016, 3 - 4 p.m.
Hall 11, Room 1124, 3rd Floor
www.globalgap.org/events
WorkiNG to improve the
sustaiNability of
CompouNd feed produCtioN
www.globalgap.org/cfm
International Aquafeed - March | April 2016 | 25
FEATURE