Post Grad: Megan Kemski
PI: Dr. Macdonald Wick, Dept. of Animal Sciences
As the global demand for seafood continues to increase, aquaculture production has grown rapidly to meet this demand, while wild caught fish production has remained stagnant since 1985. However, its continued growth is limited due to narrow profit margins and feed (fish meal) being the highest operating cost for farmers. In an effort to reduce production costs as well as reliance on wild caught fish used for aquafeeds, higher amounts of plant-based protein sources are being incorporated in diet formulations. One of the most promising fish meal replacements is soybean meal, which is currently, around one fifth the price of fish meal per ton.
A project is underway in which yellow perch (Perca flavescens) are being fed diets with either fish meal (FM) or soybean meal (SBM) that replaces 75% of the FM as the protein source in the diet formulation. At such high SBM inclusion levels, it is hypothesized that there will be an accumulation of soy isoflavones within the fish muscle. We will quantify the deposition of individual isoflavones (genistein, daidzein and glycitin) in both their glucoside and aglycone forms in yellow perch fillets by high-performance liquid chromatography (HPLC). Isoflavone content present in pure soybean meal will be analyzed, as well as the existing amounts in the formulated SBM diet. This will allow us to determine the initial amount of isoflavone content in the SBM, and consequently, if levels are being affected by the diet formulation process. By quantifying isoflavone concentrations in the diet, we can also estimate a relative amount of isoflavone ingestion fish are receiving based on feeding rates. Subsequently, isoflavones will be extracted and analyzed for amount present in yellow perch fillets. Fish will be sampled at 60 days, 6 months, 12 months and 72 months after being fed SBM, along with a control (FM) group fish, which have never been fed soy.