To improve the reputation of US soybean meal and promote the use of soy-optimized diets, we must continually demonstrate and promote the use of soy-based feeds as economically viable and sustainable solutions. Towards this goal, are systematically demonstrate the utility of US soybean meals in shrimp feeds from various soybean meal types which may improve the performance of shrimp. Results of this work are intended to produce science-based demonstration of the efficacy of soy optimized feeds for shrimp. The work utilized traditional measures of performance (e.g., growth, survival, and nutrient retention) as well as health metrics such as shift in gut structure, enzyme activity and immune system responses.
For this work, we sourced “generic” solvent extracted soybean meal from our local vendor and used this as the reference in our basal diet at an inclusion level of around 50% of the diet. This soybean meal was then partially (50%) or totally (100%) replaced to create a series of diets that include: Basal diet and diets with a) Bright Day, a new genetic high protein low oligosaccharide meal from Benson Hill (50% and 100% replacement); b) Hamlet HP300, a fermented soybean meal from Hamlet Protein (50 and 100% replacement) c) Soycomil PE, a soy protein concentrate from ADM (50% and 100% replacement) d) modified expeller pressed soybean meal from All Sustained Inc. (100% replacement) as well as a reference diet with no soybean meal (replace with fishmeal and poultry meal). These diets were fed to juvenile shrimp (0.42g initial mean weight) in an outdoor green-water system which mimics a pond-based environment.
Growth response of the shrimp in the outdoor green water system was typical with good survivals (92.2 to 100%), final weights (18.06 to 20.95g) and low feed conversion ratio (1.05 to 1.24). Results of the present work demonstrated that the soy-based diet outperformed the animal-based diet confirming the importance of plant-based protein sources. The growth parameters, as a whole, indicated we can roughly divide the results into three groups of response. Shrimp offered the basal diet and those containing SPC 50%, SBM-LO 50% and SBM-LO 100 % diets showing the highest performance. Shrimp offered diets containing fermented SBM 50 and 100 % were in the middle group, while shrimp offered EPSBM 100 %, SPC 100% and animal diets showing lowest performance. Data pertaining to gene expression and histology did not indicate any clear shifts due to soy source as compared to that of shrimp offered the animal meal-based diet. These results would indicate that shrimp do respond differently to the various soy processing systems and that the low oligosaccharide variety has a number of advantages. Surprisingly the use of fermented soybean meal, which typically produces better results due to enhanced digestion and reduced antinutrients, resulted in an intermediate performance of the shrimp. As has been reported in other studies, high level of SPC or EPSBM result in reduced performance. Irrespective of the protein source, there were limited changes in the digestive enzymes, inflammatory genes and gut histology that would warrant concern.