Effect of three dietary oils on disease susceptibility in Arctic charr (Salvelinus alpinusL.) during cohabitant challenge withAeromonas salmonicidassp.salmonicida

Abstract

Arctic charr (Salvelinus alpinus L.) were fed diets based on a commercial recipe supplemented with either linseed, soybean or marine oil prior to cohabitant challenge with Aeromonas salmonicida ssp. salmonicida. Mortality varied significantly between the three dietary groups. Highest mortality (48%) was observed in fish fed the marine oil and the lowest mortality (20%) was in the group fed soybean oil. Transmission electron microscopy (TEM) examination of the digestive tract of uninfected fish demonstrated substantial numbers of bacterial cells between microvilli. However, only a few bacteria were recovered that were associated with the microvilli of infected fish. Immunocytochemical staining/labelling investigations using TEM and an immunogold method were performed on mid‐gut segments of fish fed the marine oil diet and showed augmentation of goblet cells and the presence of A. salmonicida ssp. salmonicida in the gastrointestinal tract of diseased fish after challenge with the pathogen. It is suggested that the gastrointestinal tract could be an infection route of A. salmonicida ssp. salmonicida. The greater prevalence of goblet cells supports the suggestion that sloughing off mucus is a protective response against bacterial infections. These results make an important contribution to our understanding of how nutrition can affect the disease resistance of fish.

Dietary Effect of Soybean (Glycine max) Products on Gut Histology and Microbiota of Fish

“…In a long-term feeding study using SBO and FOs, Waagbø et al (1993) showed that Atlantic salmon fed high levels of FOs had better survival when infected with Aeromonas salmonicida (the causative agent of furunculosis), despite the fact that head kidney macrophage phagocytosis and bacterial killing was reduced in these fish (IL-1 and serum hemolytic activity was unaffected). In contrast to these results, Gjøen et al (2004) reported no differences in Atlantic salmon susceptibility to infection by A. salmonicida, while Lødemel et al (2001) reported that Arctic charr fed diets supplemented with SBO and challenged with A. salmonicida showed elevated survivability compared to fish fed a FO based diet (SBO = 20% mortality vs FO = 48% mortality).…”

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…These differences generally seem to disappear at lower temperatures, suggesting an additional temperaturedependent role of n-3 HUFA. Furthermore, in Arctic charr fed diets supplemented with soybean oil or fish oil and challenged with Aeromaonas salmonicida (the causative agent of furunculosis), increased mortality (48%) was observed in the fish oil group, compared to the soybean oil group (20%) (Lødemel et al 2001). One group of fish supplemented with a linseed oil diet was intermediate between the two.…”

Histochemistry of glycoconjugates in mucous cells of Salmo trutta uninfected and naturally parasitized with intestinal helminths

“…Manjili et al (1998) showed that hyperplasic goblet cell and changes in the composition of goblet cell mucins follow primary infection of guinea pigs with Trichostrongylus colubriformis. In fish, an excess of secreted mucus is generally described when both intestinal and gill epithelia interact with microrganisms (Ferguson et al 1992, Guzman-Murillo et al 2000, Lodemel et al 2001, Kruatrachue et al 2003, and with intestinal helminths (George & Nadakal 1978, AdelMeguid et al 1995.…”