The effect of intermittent feeding on feed intake and compensatory growth of whitefish Coregonus lavaretus L.

Abstract

Groups of juvenile whitefish, Coregonus lavaretus, were exposed for 6 weeks to three different feeding regimes: control (fed every day); 2 + 5 (fed during weekdays); and 2 + 2 (fed 2 days, starved 2 days). The fish in the 2 + 2 group ate and grew less than the controls but the 2 + 5 group was intermediate and did not differ statistically significantly from either of the other two groups. The fish in both treatment groups exhibited clear compensation for the reduced number of feeding days by increasing intake and consequently weight gain during the days when they were fed, and the compensation increased towards the end of the experiment. Feeding treatments induced clear changes in the maximum stomach volume by the end of the experiment; measured under constant pressure, this was significantly larger in the 2 + 5 and 2 + 2 groups (4.17 ± 2.38 ml and 5.08 ± 1.70 ml, respectively) than in the controls (2.96 ± 1.13 ml). At the end of the experiment all fish were given a single meal after a 4 day feed deprivation and the fish from the two treatment groups ate significantly more (both in absolute terms and relative to body weight) than the controls. Individual stomach volume had a very strong linear relationship with the amount of food ingested during the last meal ( R 2-values for control, 2 + 5 and 2 + 2 were 0.82, 0.99 and 0.97, respectively). Average feed conversion ratios were between 0.82 and 0.86 without differing significantly between treatments. These results indicate that whitefish is capable of growth compensation through increasing stomach volume and consequent increased feed intake without a change feed conversion ratio; however, 6 weeks was apparently too short for full compensation. The results also suggest that intermittent feeding could be used for rearing whitefish and thereby potentially decreasing labour costs on a fish farm.