Diet particle size
preference and optimal ration for mud crab, Scylla serrata, larvae
fed microbound diets
J. Genodepa, P.C. Southgate, Ch. Zeng-2004
Aquaculture, 230(1-4): 493-505
Abstract:
This paper reports on experiments to determine
particle size preference and optimal ration for the various larval stages of
the mud crab, Scylla serrata, fed microbound diets (MBD). All
experiments used 14C-labelled rotifers as components of MBD, and
ingestion was determined by assessing the 14C content of S.
serrata larvae after feeding on the MBD. Five size ranges of MBD
(<150, 150–250, 250–400, 400–600 and 600–800 µm) were used to
assess ingestion by Zoea I, Zoea III, Zoea V and Megalopa. All were fed a
ration equivalent to twice the equivalent dry weight of live foods provided
to each larval stage under standard rearing conditions (standard ration).
MBD particle size preference increased with increasing larval development.
Highest ingestion rates by Zoea I, Zoea III, Zoea V and Megalopa were found
for particle size ranges of <150, 150–250, 250–400 and 400–600 µm,
respectively. MBD within these particle size ranges were used in subsequent
experiments to assessed optimum rations for each of the four larval stages.
Larvae were fed rations based on multiples or fractions of the standard
ration (100%): 12.5%, 25%, 50%, 100%, 200% and 300%. There were no
significant increases in ingestion, for any of the four larval stages, when
ration was increased above 100%. For Zoea I, Zoea III and Zoea V larvae,
there was no significant difference in the rate of MBD ingestion when ration
was reduced to 50%; however, a 25% ration brought about a significant
decrease in ingestion. There was no significant decrease in the rate of
ingestion by Megalopa when ration was reduced from 100% to either 50%, 25%
or 12.5%. The results suggest that rations currently used for larval rearing
of S. serrata may be excessive. Little is currently known of the
feeding behaviour and nutritional requirements of S. serrata larvae,
and the results of this study are a significant development in this field.