Effectiveness of functional feed ingredients to enhance gill disease in Atlantic salmon (Salmo salar, L.)

• Published in: PloS one 2024-06, Vol.19 (6), p.e0304112
• Main Authors: Vitale, Matteo, Hoel, Eirik, Yousaf, Muhammad Naveed, Kambestad, Martha Amalie, Mullins, Julia, Lagos, Leidy, Berge, Kjetil, McGurk, Charles, Pampanin, Daniela Maria
• Format: Article
• Language: English
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0304112

Herein, the feasibility of in vitro methods for screening the qualities of functional feed ingredients using the fish cell line RTgill-W1 and the culture of Paramoeba perurans was investigated. Five functional ingredients (arginine, β-glucan, vitamin C, and two phytogenic feed additives) were selected to investigate their effects on cell viability and reactive oxygen species production. Three of them (arginine and two phytogenic feed additives) were additionally tested to assess their potential amoebicidal activity. As these functional ingredients are the core of a commercial feed (Protec Gill, Skretting AS), beneficial effects were further assessed in a field trial using Atlantic salmon ( Salmo salar ), affected by complex gill disease (CGD). Threshold levels of the ingredient concentrations were identified through RTgill-W1 cell viability assay. High concentrations of all tested ingredients, except vitamin C, resulted in a significant reduction of cell viability. Different effects on reactive oxygen species production were observed among the ingredients. Arginine and two phytogenic feed additives exhibited also pronounced amoebicidal activity at the highest tested concentrations. In the field study, three weeks of feeding Protec Gill slowed the disease progression, and also led to a significant improvement in gill tissue conditions. Significant reductions of epithelial and mucous hyperplasia, predominant symptoms in fish affected by CGD, and pathogen load, particularly epitheliocystis associated with Ca . Branchiomonas cysticola , one of the major contributors of CGD, were observed. These positive outcomes underscore the potential of functional feed ingredients in ameliorating gill diseases and enhance fish health. RTgill-W1 cell line assays proved to be effective tools for screening functional ingredients, providing valuable insights into optimal concentration ranges. Implementing an in vitro cell-based approach, with additional assays and cell line types, it’s a promising alternative to reduce the number of animals used during fish trials, for a more sustainable aquaculture practice.