Effects of anaesthetisation and vaccination on feed intake and growth in Atlantic salmon ( Salmo salar L.)

Abstract

Feed intake is generally considered to be a reliable criterion to evaluate health and welfare in farmed fish. We wanted to investigate the effects of anaesthetisation and vaccination on feed intake and growth of Atlantic salmon, Salmo salar L. A feed waste collection system enabled us to measure daily feed intake without disturbing the fish. The study demonstrated that benzocaine anaesthetisation, irrespective of short or long anaesthetisation time, had a minor, not significant, short-term effect on feed intake. Fish vaccinated with an oil adjuvant vaccine, irrespective of treatment times during anaesthetisation and vaccination, had a significantly reduced feed intake in a period of 12 days after vaccination. The tendency of lower feed intake was apparent until 25 days after treatment. Artefacts such as handling and treatment times did not influence the feed intake. The reduced feed intake of the vaccinated groups was reflected in approximately 20% reduced growth at termination of the experiment, 32 days after treatment. The results show that use of feed waste collection system may be a suitable method for evaluation of side effects of vaccination, and can be used to evaluate welfare of farmed fish.