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Titolo:
Digestive enzymes in fish larvae and juveniles - implications and applications to formulated diets
Autore:
Kolkovski, S;
Indirizzi:
Dept Fisheries, Mariculture Res & Advisory Grp, N Beach, WA 6920, Australia Dept Fisheries N Beach WA Australia 6920 Grp, N Beach, WA 6920, Australia
Titolo Testata:
AQUACULTURE
fascicolo: 1-2, volume: 200, anno: 2001,
pagine: 181 - 201
SICI:
0044-8486(20010815)200:1-2<181:DEIFLA>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
DICENTRARCHUS-LABRAX LARVAE; SEABREAM SPARUS-AURATA; HERRING CLUPEA-HARENGUS; SCOPHTHALMUS-MAXIMUS L; TROUT SALMO-GAIRDNERI; FREE AMINO-ACIDS; GILTHEAD SEABREAM; RAINBOW-TROUT; ARTIFICIAL DIETS; COMPOUND DIET;
Keywords:
digestive enzymes; fish larvae; fish juveniles; live food; formulated diets;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
103
Recensione:
Indirizzi per estratti:
Indirizzo: Kolkovski, S Dept Fisheries, Mariculture Res & Advisory Grp, POB 20, N Beach, WA 6920, Australia Dept Fisheries POB 20 N Beach WA Australia 6920 20, Australia
Citazione:
S. Kolkovski, "Digestive enzymes in fish larvae and juveniles - implications and applications to formulated diets", AQUACULTURE, 200(1-2), 2001, pp. 181-201

Abstract

Age-dependent changes in digestive tract anatomy/physiology during larval-juvenile 'metamorphosis' of fish have been examined with respect to diet, biochemical characteristics and nutrient utilization. In fish larvae, basal capacity and rates of the intestine to hydrolyze and transport specific nutrients is qualitatively and quantitatively set in genetic memory, to correspond to a natural diet. With this premise in mind, we should be able to produce "artificial zooplankton" which would satisfy the needs of all larval fish. At first feeding, the digestive tract in most fish species contains the enzymes related to metabolism (digestion, absorption and assimilation) ofmolecules such as proteins, lipids and glycogen. The enzymes' activity hasbeen observed to be relatively low compared with adult fish levels. Each enzyme develops independently during ontogenesis, with variation related to fish species and temperature. It has been suggested that the live food (i.e. zooplankton) organisms consumed by the larvae assist the digestion process by 'donating' their digestive enzymes, either by autolysis or as zymogensthat activate the larval endogenous digestive enzymes. Live food organismsalso contain gut neuropeptides and nutritional 'growth' factors which enhance digestion. These substances are frequently omitted in formulated diets. Moreover, particulate diets for larvae contain proteins and other ingredients that are difficult to digest, (especially since formulated diets are 60-90% dry matter while zooplankton is only 10%). Based on this hypothesis, the inclusion of different digestive enzymes, especially proteases, in the diets for fish larvae resulted in significantly improved nutrient utilisation and performance of the larvae; however, these were still not at the levelof live food-fed larvae. The next step, inclusion of pre-hydrolysed proteins in the diets, gave mixed results depending on percentage of hydrolysate and larval age. The effect of inclusion of digestive system neuropeptides in formulated diets was investigated with different fish species in recent years. The results suggest that inclusion of bombesin may increase assimilation of diets and larval growth. However. other trials with juvenile fish have shown no effect of these additions of the neuropeptide. Future research needs to be focused upon deriving a greater knowledge of ontogenic development of the larval and juvenile digestive systems and the application of this knowledge to diet formulation. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 03:23:19