early weaning of winter
flounder larvae (pleuronectes americanus walbaum) on a commercial
microencapsulated diet.
I.
Ben Khemis, R. Fournier, J. De la Noüe, C. Audet
Abstract :
A previous work, on the use of a microencapsulated
diet as a total or partial replacement of live prey for feeding larvae of
winter flounder (Pleuronectes americanus), suggested that proper
assimilation of the diet begins at the onset of stomach differentiation
(larval size about 5.5 mm). The present work was undertaken to test whether
from that stage the larvae could be weaned onto the microencapsulated diet.
The assessment of the adequacy of this early weaning was firstly examined by
comparing growth performances (standard length, total protein content and
age at metamorphosis) of larvae fed enriched live preys from first feeding
to the size of 5.5 mm and then reared on three different feeding regimes
until metamorphosis: 1. live preys as a control group, 2. co-feeding of live
prey and microencapsulated diet, and 3. exclusively microencapsulated diet
after fast weaning in four days (larval size of 6.2 mm). No differences were
observed between larval development of the two groups which began
metamorphosis at 40 days old. The larvae of the third group showed a
significantly slower growth which resulted in a delay of four days for
beginning of metamorphosis. In a second experiment with treatments 2 and 3,
the transition weaning period was lengthened to a development stage of 6.6
mm. The weaning at that stage resulted in no loss of growth or delay for
metamorphosis.
(ISMER,
Université du Québec à Rimouski, Rimouski, QC G5L 3A1, Canada)