Gastric emptying in Limanda limanda (L.) and the return of appetite

Abstract

Limanda limanda (35–225 g) fed during daytime when trained to use demand feeders under natural photoperiods. Under continuous illumination different feeding rhythms developed which were detected by periodogram analysis. Interfeeding periods (P hours) varied with body weight (W grams) and temperature (T° C) over the range 6.5–15° C as: In P=4.4 – 0.167 (In W) – 0.05 T. Daily food intake (D grams increased with both temperature and size (In D = 0.099 T + 0.579 In W – 3.49). Relative daily intake (R as % body weight, b.w) increased with temperature but decreased with size (In R = 0.099T–0.41 In W + 1.05). These changes in daily intake are primarily caused by changes in feeding frequency; the amount eaten at a meal is relatively constant save at low temperatures (6.5° C) when appetite is suppressed. Dilution of the food with kaolin (from 4.8 to 2.2 kcal/g) did not cause a compensatory increase in meal size or frequency. Gastric emptying time (GET hours) measured by X‐radiography changed with body weight, temperature and relative meal size (M % b.w.) as In GET = 0.68 In M + 0.39 In W – 0.035T + 1.46. With the exception of the lowest temperature (6.5° C) interfeeding periods closely followed GET (P = 1.09 GET – 2.6) supporting the proposal that stomach fullness is a major factor controlling appetite in the dab.