Effects of temperature decrease on feeding rates, immune indicators and histopathological changes of gilthead sea bream Sparus aurata fed with an experimental diet

Gilthead sea bream Sparus aurata were fed with either a commercial feed or a specifically prepared winter feed in order to assess whether fish showed signs similar to the so-called winter syndrome and whether the experimental diet showed protection against the syndrome. Fish were subjected to a ramp of temperature decrease and after 2 weeks, a further recovery of temperature. The temperature ramp produced changes on most immune indicators and feed intake was affected more severely than predicted by feeding tables. However, no generalised signs of the syndrome were detected. The experimental diet tested showed some degree of immune protection related to complement and phagocytosis activity and slight changes in the levels of leucocytic infiltration of the intestinal mucosa and submucosa. (C) 2004 Elsevier B.V. All rights reserved.