Feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum) with live prey or microencapsulated diet: linear growth and protein, RNA and DNA content
I. Ben Khemis et al., Feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum) with live prey or microencapsulated diet: linear growth and protein, RNA and DNA content, AQUAC RES, 31(4), 2000, pp. 377-386
A commercial microencapsulated diet was used as a total or partial replacem
ent of live prey for feeding larvae of winter flounder Pseudopleuronectes a
mericanus (Walbaum), a potential alternative finfish species for coldwater
marine aquaculture. Growth performance (morphometric measurements and bioch
emical composition) and nutritional condition (RNA/DNA ratios) of larvae fe
d live prey (Brachionus plicatilis Muller), a microencapsulated diet or a m
ixed diet of live prey and microcapsules were compared. Newly hatched larva
e were unable to digest microencapsulated diet; live prey at initial feedin
g was required for their survival and growth. Larvae offered a mixed diet s
howed slower growth than larvae fed exclusively with live prey. However, at
the onset of stomach differentiation, RNA/DNA ratios (indicators of protei
n synthesis potential) of the larvae fed both diets became similar. We sugg
est that, at that stage (size 5.5-6.3 mm), enzymatic activity had developed
enough to allow digestion of inert food. As the RNA/DNA ratio is a good in
dicator of nutritional condition, it appears to be an interesting tool for
the assessment of diet adequacy in marine larval feeding technology.