A comparative study of automatic feeding and self-feeding in juvenile Atlantic salmon ( Salmo salar) fed diets of different energy levels

Abstract

The growth performances of juvenile Atlantic salmon fed diets differing in energy content, either using self-feeders or in excess with automatic feeders, were compared. In addition, the pattern of feeding activity is described for fish fed with self-feeders. In fish fed using self-feeders, growth was intermediate between the performance of fish fed with low and high energy diets by means of automatic feeders. Fish groups tended to become more homogeneous in size with the passage of time, this being more pronounced in groups fed using self-feeders than in those fed using automatic feeders. Dietary energy content influenced growth and digestible energy intake of salmon fed by means of automatic feeders, but this was not seen in self-fed salmon. These results indicate that regulation of feed intake is influenced by the feeding strategy, probably because pellets are only available on demand for fish fed with self-feeders, whereas in groups fed by means of automatic feeders, pellets are freely available in excess. In fish fed with self-feeders, all feed distributed appeared to have been eaten. Feeding activity showed a main peak during the first hours of light and a second, smaller, peak at the end of the light phase. It is concluded that Atlantic salmon feeds preferentially during the photophase and can be fed efficiently with self-feeders.