The influence of nocturnal vs. diurnal feeding under winter conditions on growth and feed conversion of European sea bass (Dicentrarchus labrax, L.)

European sea bass display predominantly nocturnal self-feeding patterns in winter and early spring, and this has been further examined by comparing th e effect of night and day feeding on growth and feed conversion. To this en d, three feeding regimes were compared: nocturnal automatic-feeding (NF), d iurnal automatic-feeding (DF) and free access to self-feeders (SF). Under N F, feed was supplied in two meals differing in size (pre-dawn and post-dusk , 33.33: 66.67% of daily feed ration, respectively). In DF feed was supplie d in three equally-sized meals (morning. afternoon and evening, 33.33: 33.3 3: 33.33% of daily feed ration). The experiment was carried out from Januar y to April. Under SF, sea bass showed a phase inversion of daily feeding rh ythms, which changed from an initial nocturnal to diurnal by the end of the experiment. Feeding strategies affected specific growth rate (SGR) and fee d conversion ratio (FCR), the highest SGR and the lowest FCR being obtained with SF and NF treatments (SGR: 0.26 +/- 0.01 in NF vs. 0.19 +/- 0.01 in D F; FCR: 2.65 +/- 0.08 in NF vs. 3.73 +/- 0.17 in DF). The results demonstra te that feeding sea bass by night in winter, when they show nocturnal behav iour, may improve their growth and feed efficiency. (C) 2000 Elsevier Scien ce B.V. All rights reserved.