The effects of commercial feeding procedure on cortisol levels of sea bass (Dicentrarchus labrax) larvae

In this study, it is aimed to determine the effects of microparticles feeds [O.range start (100-200µm, 200-300µm), Gemma Wean (150-300µm, 200-400µm), Samba (300-500µm)] and enriched live foods [Rotifer, Artemia naupli ve metanaupli]on cortisone levels of sea bass larvae (Dicentrarchus labrax L. 1758) and protease activities of larvae. Protease activities of sea bass larvae have changed between 22.98 U/mg protein (51 th) and 255.63 U/mg protein (11 th). Protease activity values according to the live and microparticle feeds with develoment times of the larvae were significant compared to Tukey multiple comparison methods (P<0.05). However, the effects of microparticle feeds on the average protease activities of the larvae between 31-66 days were found to be similar (P˃0.05). The protease activities of Rotifer, Artemia nauplii and Artemia metanauplii were found as 5.55 U/mg, 23.45 U/mg protein and 177.38 U/mg protein, respectively. The lowest average cortisol level of sea bass larvae was found 0.0016 ng/g (6 th) and the highest average cortisol level was found 0.0069 ng/g (days of 56 and 61). Differences between cortisol levels of larvae were found to be significant. (P<0.05). These values have started to increase since the 11th day. However, cortisol levels of larvae have increased since day 26 with the use of different microparticle feeds. (P<0.05).