The use of exogenous enzymes in feeds for terrestrial livestock, notably poultry and swine, has been widely adopted by the industry given the positive effects of these additives in improving the nutritional value of plant-based feeds largely comprised of soybean meal (SBM) and corn. Inclusion of carbohydrase enzymes in feeds have shown to improve the digestibility of otherwise indigestible oligosaccharides and non-starch polysaccharides present in plant-based protein and energy ingredients for monogastric animals. Likewise, the supplementation of protease enzymes to poultry and swine feeds has been shown to increase the availability of proteinogenic amino acids by enhancing protein digestibility. Such positive effects of enzyme additives translate into economic and environmental benefits by directly improving production efficiency, reducing pollution by the unabsorbed nutrients by the animals, and reducing the footprint of livestock production.
Although well established in the poultry and swine industries, the use of enzyme additives in aquaculture feeds is still incipient and information regarding their efficacy in aquatic animals is limited to only a few species. However, considering the increased use of plant-based ingredients in aquaculture feeds in recent decades and the similarities in digestive physiology between terrestrial monogastric animals and fish, the efficacy of commercial enzyme additives to improve the nutritional value of plant-based feeds to fish should be investigated. Therefore, the objective of this research is to assess the effects of commercial enzyme additives in SBM-based diets for hybrid striped bass (HSB), one of the main food fish in the U.S. aquaculture industry.
To this end, two feeding trials are being proposed. The growth trial would evaluate five SBM-based diets containing commercial carbohydrase and protease enzymes in different combinations and levels, and would assess the effects of the additive enzymes on the production performance of the fish. In the digestibility trial, the effects of the additive enzymes on the digestibility of the diets by advanced HSB juveniles would be assessed. The research project would be carried out at the Aquatic Animal Nutrition Laboratory located in the Aquaculture Research Center of Kentucky State University, Frankfort, KY, following standard research protocols. A graduate student in the Master's in Aquaculture program would be directly involved with conducting the feeding trials under the supervision of the principal investigator and two full-time research assistants. Results from the research project would be made available to the public through conference proceeding abstracts and presentations, as well as technical and peer-reviewed publications.
The potential outcomes of this research project include: i) the supply of information about the applicability of carbohydrase and protease enzyme additives to enhance the nutritional value of SBM-based diets for HSB; ii) increasing the awareness of the aquaculture industry about available tools that can be used to optimize plant-based feed formulations for farmed fish; iii) and encourage further research on enzyme additives specifically designed for aquatic animals.