Ontogeny of the
digestive capacity of Senegalese sole (Solea senegalensis), with
respect to digestion, absorption and metabolism of amino acids from
Artemia
S. Morais, M. Lacuisse, L.E.C. Conceição,
M.T. Dinis, I. Rønnestad-2004
Marine Biology, 145(2): 243-250
Abstract:
Ontogenetic changes in the capacity of Senegalese sole
(Solea senegalensis Kaup, 1858) larvae to digest and metabolise
Artemia protein and amino acids (AA) were studied using 12, 22 and 35 days
after hatching (DAH) larvae that were fed Artemia metanauplii
radiolabelled with a [U-14C] protein hydrolysate. About 82% and
18% of the label was incorporated into the Artemia trichloroacetic
acid (TCA) precipitate (mostly protein) and soluble (mainly free AA)
fractions, respectively. The digestibility of Artemia was high at all
tested ages, with label absorption varying between 77% and 83% at 24 h
after feeding (HAF). A rapid digestion, absorption and catabolism of
Artemia AA were noted, with most of the absorption into the body
occurring during the first 3 HAF. Traces of label were already found in
the metabolic-CO2 trap at 1 HAF. Furthermore, label was
largely and almost immediately incorporated into the TCA precipitate
fraction (mostly protein) of gut and body tissues. Slight differences were
noted in diet utilization between larvae at different ages. At 12 DAH
larvae had a lower catabolism and evacuation of the label, as well as the
highest accumulation in the gut. However, except for the amount of
catabolised label, the results were not significantly different from those
for 35 DAH larvae. Moreover, no significant differences were found in
the amount of label incorporated into the body, although it seemed to be
higher in 12 DAH larvae. Taken together, these results reveal a higher
absorption and a significantly higher retention of the absorbed label in 12 DAH
larvae. In addition, 12 DAH larvae appeared to have a slower absorption
of the label, which, in continuously feeding larvae, might result in overall
lower food absorption efficiency. Therefore, it seems that young larvae have
the ability to compensate for a possible lower digestive capacity with
higher body retention of absorbed AA. This study confirms that sole larvae,
even young stages, have a high capacity for digesting live preys.
(CCMAR, Universidade do Algarve,
Campus de Gambelas, 8005-139 Faro, Portugal, e-mail: smorais@ualg.pt)