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 the effect of night and day feeding on growth and feed conversion. To this end, three feeding regimes were compared: nocturnal automatic-feeding (NF), diurnal automatic-feeding (DF) and free access to self-feeders (SF). Under NF, 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 supplied in three equally-sized meals (morning. afternoon and evening, 33.33: 33.33: 33.33% of daily feed ration). The experiment was carried out from January to April. Under SF, sea bass showed a phase inversion of daily feeding rhythms, which changed from an initial nocturnal to diurnal by the end of the experiment. Feeding strategies affected specific growth rate (SGR) and feed 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 DF; FCR: 2.65 +/- 0.08 in NF vs. 3.73 +/- 0.17 in DF). The results demonstrate that feeding sea bass by night in winter, when they show nocturnal behaviour, may improve their growth and feed efficiency. (C) 2000 Elsevier Science B.V. All rights reserved.