C. Burrells et al., Dietary nucleotides: a novel supplement in fish feeds 1. Effects on resistance to disease in salmonids, AQUACULTURE, 199(1-2), 2001, pp. 159-169
To determine the effects of the inclusion of exogenous nucleotides in aquac
ulture diets on the resistance of fish to various challenge infections, tri
als were carried out and results presented. When added to normal fish feed
formulations at a combined inclusion level of 0.03%, these additional nucle
otides were shown to increase resistance to challenge infections with bacte
rial. viral and rickettsial diseases as well as ectoparasitic infestation.
When fed for 3 weeks prior to challenge, the nucleotide-supplemented diet w
as superior (31% mortalities: relative percent survival: RPS = 37%) to a be
ta -glucan-containing diet (43% mortalities; RPS = 12%) in reducing mortali
ties due to Vibrio anguillarum infection in fish fed the control diet (49%
mortalities). Mortalities resulting from infections with infectious salmon
anaemia (ISA) virus and Piscirickettsia salmonis were also significantly re
duced (RPS = 25.7% and 42.1%, respectively) as were the numbers of infestin
g sea lice (Lepeophtheirus salmonis) (37.8% reduction in the mean number of
attached lice per fish). The mode of action of supplemental dietary nucleo
tides and advantages over recognised immunostimulants are discussed. (C) 20
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