Short fasting and refeeding in red porgy (Pagrus pagrus, Linnaeus 1758): response of some haematological, biochemical and non specific immune parameters.

A short fasting-refeeding experience was applied to specimens of red porgy, Pagrus pagrus (Teleostei, Sparidae) to assess its effects on some physiological parameters. Haematological (haematocrit), biochemical (serum cortisol and glucose) and immunological (lysozyme, haemolytic and haemagglutinating activities) parameters were measured. For this study, two fish groups were considered: one was fasted for 14 days and then refed to satiation during further 7 and 15 days (indicated as fasted/refed group), the other was fed throughout the study and was taken as a control group. Significantly lower values were recorded for the condition index, the hepato-somatic index and viscero-somatic index in the fasted/refed group compared to the fed one. Fasting did not affect significantly the examined parameters, except for cortisol; refeeding for 7 days induced a significant increase in the haemoagglutinating titre and the spontaneous haemolytic activity, but when refeeding was extended to 14 days haemagglutinating and haemolytic values remained lower than those measured in fed fish.