- Agronomic: soybeans
- Animals: fish
- Animal Production: feed/forage, feed formulation, preventive practices
Two of the main concerns facing aquaculture expansion in the foreseeable future are sustainable protein sources and disease outbreaks. Currently, fish meal is the main source of protein in carnivorous fish diets, and the world supply of fish meal is quickly being outpaced by that of demand. Soy protein is a sustainable way to replace much of the protein requirements in aquafeeds currently being filled with fish meal. Each species of commercially produced marine fish has different protein requirements, and different physiological responses to soy protein. Therefore each species which is cultured must be reviewed to investigate the individual response to fish meal replacement. Disease outbreaks in hatcheries, as well as grow out facilities can be economically crippling to the developing fish farming industry in the northeast. Preliminary experiments incorporating soybean meal into feed for summer flounder (Paralichthys dentatus) have shown potential immunostimulatory benefits. The commercial fish farms in the northeast have struggled with disease outbreaks, and have shown interest in a sustainably produced diet which can reduce disease outbreaks while providing no reduction in growth rates. Therefore if soybean meal can provide comparable growth rates while simultaneously stimulating immune function, it could not only provide a new market for soy products but also reduce mortality at fish farms and provide the economic advantage aquaculture farms need in order to expand and continue to provide jobs and a sustainable, high quality protein source for human consumption.
Project objectives from proposal:
It is important to evaluate the amount of soy protein which can be incorporated into a diet for a given fish species, as well as evaluate the changes a new protein source has on growth, physiology, and immune function.
I propose to evaluate the inclusion of soybean meal (SBM) or soy protein concentrate (SPC) into the diet of Summer flounder juveniles (Paralichthys dentatus) in order to evaluate the effect on: growth, gut histology, and immune system function (objectives 1 – 3). I plan on cooperating with the two pioneering commercial aquaculture companies in the Northeast growing summer flounder as well as other marine finfish species (Local Oceans, Hudson NY; GreatBay Aquaculture, Portsmouth, NH), in order to help them evaluate the inclusion of soy protein into their feeds (objective 4).
Objective 1: Create feeds with fish meal replaced by SBM or SPC to various levels, with balanced amino acid profiles, including additions of taurine and phytase.
The concentrations of the 10 essential amino acids for marine fish are lower in soybean meal (SBM) than fish meal (except cytosine), and SBM also contains high levels of carbohydrates. Oligosaccharides commonly found in SBM have been reported to be indigestible to fish and have been linked to low growth performance, and lectins and phytic acid found in high levels in SBM can impair fish growth (Gatlin et al., 2007). Therefore I will create balanced amino acid profiles and include taurine (to increase digestibility) and phytase (to reduce phytic acid) in the diets replacing fish meal with SBM or SPC.
Objective 2. Feed the diets with SBM or SPC inclusion to summer flounder. Evaluate growth, feed conversion, hematological profiles, immune function, and histological changes to the intestines.
The inclusion of soy as a protein source will be evaluated over a 12 week feeding period in comparison with a standard fish meal diet. At the conclusion of the study we will determine effectiveness through statistical analysis of growth, survival, and feeding efficiency and conclude the impact of the diets on overall fish health and improved productivity.
Objective 3. Evaluate effect of SBM on mortality when challenged with Vibrio harveryi.
The pathogen V. Harveyi is known to be detrimental in hatcheries (George Nardi, per comm.) and will serve as an excellent challenge in order to evaluate immunostimulation properties of SBM.
Objective 4. Disseminate results to commercial partners, and present findings at sustainable aquaculture venues in the Northeast.
All fish will be purchased from GreatBay Aquaculture in Portsmouth, NH, and we will be in direct contact with the hatchery throughout the project to update them on the progress. The summer flounder grow-out facility Local Oceans, has expressed interest in the outcome of this project as well. We will present our findings at both of these commercial partners in order to help them decide if soy inclusion would help their business. We will also present our findings both at scientific conferences as well as opportunities at universities and research institutions in the northeast.