Effect of Long‐term Oral Administration of an Immunostimulant Diet on Innate Immunity in Sea Bass (Dicentrarchus labrax)

Abstract

Immunostimulants represent a modern and promising tool in aquaculture, enhancing the resistance of cultured fish to disease and stress. This study investigated the effect of a combination of dietary glucans, a-tocopherol and ascorbic acid on the innate immune response of cultured sea bass (Dicentrarchus labrax). After 5 weeks of adaptation on a commercial diet containing 100 p.p.m. ascorbic acid and 200 p.p.m. atocopherol, sea bass were switched to a diet supplemented with 2 % b-1.3/b-1.6 glucans and ascorbic acid and a-tocopherol at 500 p.p.m. The supplemented diet was given at 2 % of body weight per day over a 2week period, every 3 months. Plasma lysozyme concentration, content and distribution of major plasma proteins and complement activity were measured prior to feeding the supplemented diet and after 40 weeks. Alternative pathways of complement activation and lysozyme activity were both significantly enhanced in fish fed on glucans and elevated doses of vitamins. No significant differences were observed in protein content or in albumin/globulin ratio. Compared to lysozyme activity, which showed marked individual variation, complement-mediated haemolytic activity has been shown to be a more reliable indicator of sea bass immunocompetence. Further studies are in progress to clarify the effect of each dietary component on the innate immune response and disease resistance. U. S.

Effect of dietary seaweed supplementation on growth performance, antioxidant and immune responses in European seabass (Dicentrarchus labrax) subjected to rearing temperature and salinity oscillations

“…(Valente et al 2006) and in European seabass fed diets with algal extract (Lauridsen and Buchmann 2010). On the other hand, an increase in lysozyme concentration was reported in European seabass when fed a seaweed supplemented diet (Peixoto et al 2016c) and when fed a combination of dietary glucans and vitamins (Bagni et al 2000), contradicting present results. Given this, we hypothesize that the beneficial effects of seaweeds on the innate immune response may be highly influenced by biotic and abiotic factors such as species, age, weight, rearing water conditions, and/or seaweed composition.…”

“…To solve this, alternative strategies of environmental-friendly techniques are constantly being explored. These alternatives include chemical therapy, vaccination (Bagni et al 2000;Sakai 1999), or the application of dietary immunostimulants.…”

“…The use of dietary immunostimulants has been studied as a viable complement or alternative to traditional methods and has become widely accepted by fish farmers (Bricknell and Dalmo 2005). Immunostimulants, used as dietary supplements can improve fish immunity, increasing resistance during periods of great stress or more resilience during periods of deteriorating water conditions (Bagni et al 2000). In vivo experiments with bacterial challenges recognized immunostimulants as antiparasitic, growth enhancers, and antibody production promoters (Bricknell and Dalmo 2005).…”

Immunostimulant effects of Cotinus coggyria on rainbow trout (Oncorhynchus mykiss)

“…[17]. 50 ml of serum was added as triplicate into the plate and then mixed with 50 ml of PBS (pH 5.8).…”

Effects of Short- and Long-Term Glucan Feeding of Rainbow Trout (Salmonidae) on the Susceptibility to <I>Ichthyophthirius Multifiliis</I> Infections

“…In fact, in vitro studies have demonstrated that macrophages elicit a respiratory burst following beta-glucan exposure but also that the response of isolated cells is immediate and fades after prolonged stimulation (Chettri et al 2010). However, feeding sea bass with glucan-supplemented feed (0.1%) for extended periods did not result in decreased responsiveness of fish (Bagni et al 2000(Bagni et al , 2005. Neither did long term administration of low dosages (0.01%-0.05%) to rohu carp (Labeo rohita) lead to a decrease of the resistance to challenge infections using Aeromonas hydrophila and Edwarsiella tarda (see Misra et al 2006).…”