A preliminary study on the
molecular weight profile of soluble protein nitrogen in live food organisms
for fish larvae
A.P.
Carvalho, A. Oliva-Teles, P. Bergot-2003
Aquaculture, 225(1-4) : 445-449
Abstract:
The solubility of protein nitrogen at pH 8 in the
organisms used as live food for fish larvae (rotifers and Artemia)
was determined and the molecular weight profile of soluble protein nitrogen
was analysed by HPLC-gel filtration chromatography. Soluble nitrogen
accounted for 61% of total nitrogen in microalgae-fed rotifers, 47% in
starved rotifers and 54% in newly hatched Artemia. A remarkable
similarity in the profile of molecular weight distribution of soluble
nitrogen was noticed among these three types of live food. The molecular
weights of soluble nitrogen was partitioned as follows, respectively, in
rotifers and Artemia: 84–88% and 89% >500 Da (corresponding
mainly to proteins, poly- and oligopeptides), 8–11% and 4% from 200 to 500
Da (corresponding mainly to di- and tripeptides), 3–4% and 7% <200 Da
(corresponding mainly to free amino acids). According to these results,
nitrogen of both live food organisms would be available in nearly identical
forms and proportions in the intestine of fish larvae. Thus, it is suggested
that artificial diets for fish larvae should have a nitrogen solubility and
molecular weight profile similar to that found in live food.