Feed intake in Atlantic salmon fed with or without surface spreading of feed

Abstract

In intensive salmon farming, it is common practice to spread the feed over a large surface area, assuming that spreading of the feed increases feed intake in the fish. However, the impact on the feed pellets during spreading results in feed loss due to pellet breakage. In this study, feed intake, growth and signs of aggressive behavior was compared in salmon fed without or with spreading of the feed on the surface area of the tanks. Atlantic salmon (Salmo salar) with initial body weight 0.6 kg were kept in 3.3 m 3 tanks supplied with sea water (salinity 32 %, mean temperature 11 °C) for one month. The salmon were fed one meal daily, either by dropping the feed from one point, or by spreading the feed over the water surface. Feed intake and growth was measured. Fin damage was given a score at termination of the trial as a measure of competitive behavior during feeding. The relative feed intake (i.e. percent of body weight per day) in salmon fed without spreading or with spreading of the feed was 0.63±0.05 and 0.64±0.02 %, respectively. The growth rate was identical in salmon fed without or with spreading of the feed, and no significant difference in variance in final weight was found. No difference in fin damage for salmon fed without or with spreading of the feed was revealed. The data showed that for the conditions used in this trial, spreading of feed had no influence on feed intake or growth of salmon.