Effect of Diets Containing Herring Oil Oxidized to Different Degrees on Growth and Immunocompetence of Juvenile Coho Salmon (Oncorhynchus kisutch)

Abstract

Growth rate and efficiency of feed conversion were reduced by inclusion of oxidized herring oil in the diet, presumably as a result of reduced digestibility of the oxidized oil and suboptimal dietary concentrations of ω3 fatty acids. There was no evidence of any toxic factors in the oxidized oil. There was no significant difference in growth rate or the efficiency of feed conversion between juvenile coho fed diets supplemented with 30 and 1030 IU vitamin E/kg. Dietary treatment did not affect haematocrit values. Immunocompetence, judged by antibody titres in response to vibrio vaccination, was similar for all treatments. Disease resistance, assessed by the rate of mortality induced by exposure of nonvaccinated fish to challenge with Vibrio anguillarum or V. ordali, was likewise unaffected by the dietary treatments.