Sustainable Marine Aquaculture

EFFECT OF SUBSTITUTING ANIMAL PROTEIN SOURCES WITH SOYBEAN MEAL IN DIETS OF SUMMER FLOUNDER (PARALICHTHYS DENTATUS)

Research Team:
Marty Riche (USDA) - Principle Investigator
Pierre Tesson (Montpellier II University)
Dave Haley
Debra Richmond

The availability of nutrients and energy in feedstuffs may vary considerably depending on a variety of factors including fish species, ingredient quality and processing conditions. Protein is an essential nutrient that must be included in the diet at appropriate levels to ensure adequate growth and fish health. However, because protein is the most expensive component of most aquaculture diets, in the near future animal protein may not be economical to use in fish diets. Having already proven reliable on other fish species, Soybean Meal (SBM) is a potential candidate to replace fish meal in flounder diets.

A feeding experiment was conducted to determine the apparent digestibility coefficient of soybean meal proteins in Summer Flounder (Paralichthys dentatus). Ten diets were formulated to contain 35 or 45% Crude Protein and a lipid level of 12%. Other ingredients were wheat flour, cornstarch, and chromic oxide, which was utilized as the non-digestible marker. Two control diets were formulated without SBM using menhaden meal composed of fishmeal, and meat and bone meal. Eight other diets were formulated with mixture of menhaden meal and SBM to test the effect of soybean meal replacement. The menhaden meal substitute was combined in three different percentages (10, 20, and 50%) and two of these diets consisted of a 70:30 mixture. This experiment was carried out for a total of 17 days, a 10-day acclimation period, and fecal sample collection of 7-days. Fecal samples were removed from the last 15% of the anal end of the intestinal tract. Samples were dried, crushed, and pelleted for nitrogen analysis. Nitrogen analyses and statistical analysis of the data are pending. Current results indicate a correlation between fish weight, length, and intestinal tract length.