| Summary: | There continues to be a pressing need to develop alternative protein feedstuffs to reduce dependence on fishmeal (FM) and other costly ingredients and thereby increase the sustainability and potential expansion of global aquaculture. In this study, three feeding trials were conducted to evaluate the effects of substituting FM, soybean meal (SBM), or a combination of both with a premium cottonseed flour (CSF) included at incremental levels in the diets of red drum and hybrid striped bass. Feeding trial 1 utilized juvenile red drum, and the remaining two trials were conducted with juvenile hybrid striped bass. Each trial was conducted in 38-L aquaria operated as a recirculating system, and each experimental diet was fed to triplicate groups of juvenile fish for 8 weeks. Red drum in trial 1 were able to readily consume diets in which up to 50% of FM protein was replaced with CSF without observing an appreciable decline in weight gain, feed efficiency or survival. Replacing 75% of FM protein with two different CSF products did result in reduced weight gain and feed efficiency of red drum. Hybrid striped bass in trial 2 were able to readily consume diets in which up to 50% of SBM protein was replaced with either fermented or non-fermented CSF without observing an appreciable decline in weight gain, feed efficiency or survival, while 75% replacement produced lower responses, and replacing 37.5% of protein from both FM and SBM resulted in the lowest responses. Hybrid striped bass in trial 3 were able to readily consume diets in which 30% of SBM and FM protein was replaced with either fermented or non-fermented CSF without observing an appreciable decline in weight gain, feed efficiency or survival. Fermentation of CSF did not substantially improve its nutritional value to hybrid striped bass. Additionally, hybrid striped bass were more sensitive to the inclusion of CSF when substituted for protein from both SBM and FM rather than SBM alone. In conclusion, diets for red drum and hybrid striped bass could conservatively ...
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