Many sources of protein have been investigated to reduce the use of fish meal (FM) in aquaculture feeds, including soybean meal (SBM). However, FM replacement in feeds for carnivorous species is limited by problems with feed intake, growth rate, and overall health associated with reduced digestibility and anti-nutritional factors found in SBM. However, soy processing strategies can reduce the effects of anti-nutritional factors and improve utilization. Therefore, we examined the possibility of further FM replacement in SBM maximized feeds for hybrid striped bass using refined soy products, soy protein concentrate (SPC) and soy protein isolate (SPI). Results indicate that further FM sparing is possible, beyond what can be achieved with SBM. For example, it is possible to reduce dietary FM content as low as 5% using SPC, and though this negatively affects growth rate, this effect may be reversed by the addition of a betaine-based attractant. Replacement with SPI resulted in such a degree of feeding reluctance that starvation and cannibalization became issues during the trial. Reducing FM content below 5-10% resulted in more variable production performance and, when using SPI, increased incidence of cannibalism. No differences in stress tolerance were observed during the trials; however, there was a trend of increasing handling mortality in fish fed the SPC diets. Refined soy proteins can be used in conjunction with SBM to spare FM, but the cost of these products, along with their acceptability to aquatic livestock, will determine the extent of their utilization in aquafeeds.

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Utilization of DNA vaccines in aquaculture has been gaining interest and recent efforts have been focused on methods of delivering DNA vaccines to fish. In the present study, a methodology was sought that could protect DNA vaccines such that they could be orally administered. The main objective of the study was to determine if a DNA vaccine could be effectively compounded into an orally administrable formulation with chitosan or polylactide-co-glycolide (PLG). The immune response of hybrid striped bass (Morone saxatilis x Morone chrysops) following oral delivery of a DNA vaccine containing Mycobacterium marinum Ag85A plasmid in either chitosan or PLG nanoparticle encapsulation was evaluated. Hybrid striped bass were divided into four experimental groups: IM immunization of the DNA vaccine as a positive control, oral delivery of uncomplexed DNA vaccine, oral delivery of chitosan or PLG alone as a negative control, and oral delivery of complexed chitosan or complexed PLG DNA vaccine. Fish were bled at regular intervals and an ELISA was used to evaluate antibody levels in individual fish. While the chitosan /plasmid DNA complex containing the Mycobacterium marinum Ag85A gene failed to produce a significant antibody response, the PLG/plasmid DNA matrix stimulated humoral immune response in the fish. / Master of Science