THE EFFECT OF DIETARY EXOGENOUS DIGESTIVE ENZYMES ON INGESTION, ASSIMILATION, GROWTH AND SURVIVAL OF GILTHEAD SEABREAM (SPARUS-AURATA, SPARIDAE, LINNAEUS) LARVAE
S. Kolkovski et al., THE EFFECT OF DIETARY EXOGENOUS DIGESTIVE ENZYMES ON INGESTION, ASSIMILATION, GROWTH AND SURVIVAL OF GILTHEAD SEABREAM (SPARUS-AURATA, SPARIDAE, LINNAEUS) LARVAE, Fish physiology and biochemistry, 12(3), 1993, pp. 203-209
The success of microdiets commonly used in the cultivation of marine f
ish larvae is limited to serving as partial replacements for live food
. This limited success is thought to be associated with a reduced dige
stive ability due to an incompletely developed digestive system. The e
nhanced growth obtained from live food has been partially attributed t
o the digestive enzyme activity of the food organism. The present stud
y was designed to test the effect of an exogenous digestive enzyme inc
orporated into a microdiet on the growth of Sparus aurata. Larval gilt
head seabream, 20-32 days old, were fed C-14 labelled microdiets conta
ining a commercial pancreatic enzyme at different concentrations (0, 0
.1 and 0.05 g/100 g dry diet). Rates of ingestion and assimilation wer
e measured and their relationship to dry weight was determined. Our re
sults show that the success of the microdiet as a food for larval gilt
head seabream was limited by the larva's low ingestion rate which only
approached its maintenance requirement. In addition, the presence of
digestive enzyme in the microdiet enhanced its assimilability by 30%.
Larval growth over ten days was 0, 100 and 200% on microdiet free of a
dded enzymes, one with added enzymes and a live food regime, respectiv
ely. It is our opinion that successful development of microdiets for S
parus aurata must be based on diets improved both in digestibility and
attraction to the larvae. Further studies are now underway to determi
ne the nutritional requirements of gilthead seabream larvae using the
experimental method developed in the present study.