Ictalurus sp. are one of the most important fish in global aquaculture due to their fast growth, and efficient feed conversion. In the United States, they are the most farmed food fish nationwide, supporting rural economies and providing affordable protein for human consumption. To enhance the sustainable production of those fish, dietary additives are essential to ensure the long-term success of catfish farming.
In this scenario β-glucans could act as immunostimulants, making fish more resistant to pathogens. Nucleotides, on the other hand, serve as building blocks for DNA and RNA, supporting cell replication, tissue regeneration, and immune response. Combining both additives may promote a synergistic effect to improve the positive outcomes even further. In this study, three treatments were tested: β-glucan derived from microalgae Euglena gracilis (0.2%), Nucleotide (0.2%), and a combination of both (0.2% of each additive) while the control group received no additives. A total of 20 aquariums (110 L; n=5) were used, with 30 fish in each (initial weight 6.77±0.12). Fish were fed rations corresponding to the tank biomass (~3.5-5%), and water quality parameters, were measured three times per week to ensure optimal environmental conditions.
After 70 days of feeding, no statistical differences were observed in production performance parameters, including final weight, weight gain, daily weight gain (DWG), apparent feed conversion ratio (FCR), and survival rate. The data were analyzed using a 2×2 factorial design. Normality and homogeneity were assessed with the Shapiro-Wilk and Bartlett tests. If these assumptions were not met, a non-parametric Kruskal-Wallis test was performed.
Complementary analyses, such as blood parameters, in vivo and in vitro immune assays, histological morphology of the intestine, and results after bacterial challenge tests will be evaluated to determine the full impact of the additives on their health. In addition, a feeding trial with Nile tilapia (Oreochromis niloticus) evaluated similar feed additives. This collaborative effort will provide valuable insights for best feeding managements for both fish species.