Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/23/2009
Publication Date: 3/1/2010
Citation: Welker, T.L., Lim, C.E., Aksoy, M., Klesius, P.H. 2010. Effects of dietary supplementation of a purified nucleotide mixture on growth, immune function, and disease and stress resistance in channel catfish, Ictalurus punctatus [abstract]. World Aquaculture Society. p. 1075.
Technical Abstract: Juvenile channel catfish (14.4 g average initial weight) were fed diets supplemented with a purified nucleotide mixture for 8 weeks. The mixture consisted of five nucleotides supplied on an equal basis as disodium salts at combined concentrations of 0 (control), 0.1, 0.3, 0.9, or 2.7% of diet. At the end of the feeding trial, the effects of nucleotide supplementation on growth, hematology, immune function, and disease resistance (enteric septicemia, ESC) were evaluated. In addition, we examined the effects of dietary nucleotides on the stress response and whether dietary supplementation had an ameliorating effect on accompanying immunosuppressive effects. Nucleotide supplementation in channel catfish diets did not significantly influence growth performance at 8 weeks. However, feed efficiency (FER) from 4 to 8 weeks was considerably improved compared to the period from 0 to 4 weeks, suggesting that significant differences may have materialized if the study had been continued beyond 8 weeks. The specific antibody response increased with increasing nucleotide concentration in diet but declined at the highest level of supplementation. Innate immunity was unaffected by dietary nucleotide supplementation. Addition of nucleotides to diet produced a dose-dependent reduction in survival of channel catfish to E. ictaluri. Although the reasons are unclear, the high levels of nucleotides supplemented in this study may have contributed to the decrease in disease resistance and apparent contradiction with innate immune and specific antibody responses. Stress resistance increased with a corresponding amelioration of the immunosuppressive effects of the stress response on non-specific immunity (lysozyme and bactericidal activity) as nucleotides increased in diet. Based on the results of this study, supplementation of nucleotides in diets of channel catfish for prevention of ESC or as a growth promoter cannot be recommended, but use of exogenous nucleotides to decrease the immunosuppressive effects of aquaculture-related stress may prove beneficial.