Ontogenetic development of the proteolytic digestion activities in larvae of Oreochromis niloticus fed with different diets

Drossou, Alexandra, Ueberschär, Bernd, Rosenthal, Harald and Herzig, K.-H. (2006) Ontogenetic development of the proteolytic digestion activities in larvae of Oreochromis niloticus fed with different diets Aquaculture, 256 . pp. 479-488. DOI 10.1016/j.aquaculture.2006.01.038.

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This study determined the effects of two test diets — a dry-phytoplankton and a trout-fry feed — and a control diet (Artemia nauplii) on tryptic activity, growth and survival rates during early life stages of Nile tilapia (Oreochromis niloticus) larvae. In addition, during a second experimental series, the interaction between trypsin and CCK (cholecystokinin) secretion was monitored in larvae fed with a PHA (phytohemagglutinin, a protein extract from the red kidney bean) enriched commercial trout-diet and compared with the data resulting from the use of the same but non-enriched feed. Subgroups were taken from the experimental units and kept under starvation. Oreochromis niloticus was chosen as a model species, since the larvae are able to intake artificial diets by the time of first feeding, and thus featuring the experiments with a manipulated micro-diet. The results demonstrated that larval mortality and growth are affected by the diet given and this was mostly observed in the group fed on dry-phytoplankton (12.2% mortality, 1.45 mg/d; control group: 2.9% mortality, 3.19 mg/d). The same larval group showed also a higher tryptic activity compared with all the other groups, which in combination with the bad survival and poor growth performance gives evidence for inadequate nutritional quality of the dry-phytoplankton feed for larvae aged more than two weeks after hatching. Every other feeding group showed good growth rates (trout-fry feed: 3.04–3.19 mg/d, with PHA enriched trout-fry feed: 2.85 mg/d), similar to the larvae fed with live prey (3.19–3.35 mg/d). A reduction of tryptic activity characterised the starvation process. These results confirm the usefulness of monitoring the individual tryptic activity as an indicator for evaluating the quality of a diet and the nutritional condition of fish larvae, but also the necessity of combining data of tryptic activity with growth and survival data for a correct interpretation. An interaction between trypsin and CCK secretion was also confirmed with this experimental approach, since induction and reduction of tryptic activity followed a reverse pattern compared with the concentration of CCK.

Document Type: Article
Keywords: Ichthyology; Fish larvae; Oreochromis niloticus; Trypsin; Cholecystokinin; Phytohemagglutinin; Digestion
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Evolutionary Ecology of Marine Fishes
Refereed: Yes
DOI etc.: 10.1016/j.aquaculture.2006.01.038
ISSN: 0044-8486
Date Deposited: 03 Dec 2008 16:51
Last Modified: 12 Dec 2017 09:25
URI: http://eprints.uni-kiel.de/id/eprint/5329

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