Published online by Cambridge University Press: 28 November 2014
The effect of dietary water content on Dicentrarchus labrax growthparameters and resistance to Vibrio anguillarum infection wasinvestigated using commercial pellets with identical energy contents and differentmoisture levels. The first experiment hypothesis was that moisturizing pelleted ration canhave an impact on Dicentrarchus labrax growth performance by theosmoregulation energy cost reduction. In a second time, the experiment explores the effectof water addition in pellets on the fish resistance to a disease. A specific device wasbuilt to uniformly moisturize dry pellets to different moisture levels, i.e. 8%, 20%, 40%and 60%. After an acclimation period and a 54-day rearing period, the control fish hadgrown from 72.7 ± 17.9 g to133.3 ± 29.4 g. Nosignificant differences were recorded for fish growth parameters. After the growth period,the tagged fish were mixed and challenged by bath exposure to live Vibrioanguillarum in triplicate. After 7 days, mortality was significantly lower inthe group of fish fed with pellets containing 60% water. Adding water toDicentrarchus labrax feed did not affect fish growth parameters butincrease its resistance to a Vibrio anguillarum infection. The moisturizing processcould be used to add specific compounds (such as probiotics or vitamins) to pellets justbefore fish feeding and could have a positive effect on fish rearing.