The use of squid protein hydrolysate as a protein source in microdiets forgilthead seabream Sparus aurata larvae

In the present study, the use of predigested proteins as an ingredient of m icrodiets offered to gilthead seabream larvae was tested. The protein sourc e (freeze-dried squid powder) was hydrolysed with protease (trypsin and pan creatin). Different levels of raw squid protein and hydrolysate (100% prote in, 50% protein/50% hydrolysate, 100% hydrolysate)were added to the microdi ets to produce a dietary protein level of 65%. For comparison, cofeeding of Artemia nauplii and microdiet as well as microdiet supplemented with pancr eatin were also offered to the larvae. The final average dry weights of 32- day-old larvae were 1.65 +/- 0.04 mg, 1.38 +/- 0.06 mg and 1.13 +/- 0.1 mg, respectively, for larvae cofed 0%, 50% and 100% hydrolysate microdiets and Artemia nauplii. Survival of larvae was not affected by protein source. Th e survival of larvae cofed Artemia nauplii and microdiet was significantly higher than that of larvae fed exclusively on microdiet (68% and 80%, respe ctively). These results suggest that the use of hydrolysate (at 50% greater ) as a protein source in diets for seabream larvae is not to be recommended .