Gastrointestinal evacuation of inert particles by turbot, Psetta maxima: evaluation of the X-radiographic method for use in feed intake studies

Abstract

Gastrointestinal evacuation of inert X-ray dense marker by turbot, Psetta maxima, was followed by use of radiography. Groups of individually tagged turbot aged 1 + years (136.5 g), were held at 16 °C and acclimatized to a feeding period of 4 hours per day. Fish were fed on pelleted feed in excess. The experimental design allowed a test of the effects of handling stress and post-prandial feeding on gastrointestinal evacuation. Repeated handling affected feed intake, but there were no significant treatment effects on gastrointestinal evacuation rate. Fish that ingested large meals displayed higher evacuation rates of markers than fish which ingested smaller meals, but total evacuation time was longer for the fish that consumed the largestmeals. Marker particles started to be voided from the gastrointestinal tract approximately 10 hours following initiation of a meal. and evacuation of marker was completed within 52 hours under the holding conditions employed in the present study.