FEED INTAKE USED TO ESTIMATE ATTRACTABILITY OF FISH MEAL, FISH MEAL PROTEIN HYDROLYSATE, CASEIN, SQUID MEAL, AND YEAST AND BACTERIAL BASED SINGLE CELL PROTEINS TO SHRIMP Litopenaeus vannamei

Successful replacement of fish meal (FM) in shrimp feeds requires an evaluation of attractability of alternative protein sources. Ingredients that enhance attractability of feed should increase timely feed intake in both extensive and intensive shrimp culture systems. Immediate feed intake leads to increased feed conversion and growth, reduced feed waste and leaching of important and expensive nutrients, and improved water quality. Products that enhance attractability and feed intake have important commercial value in the marketplace.

FM, fish protein hydrolysate (FPH), squid meal (SM), casein and two single cell protein (SCP) sources (Meridian Biotech LLC) derived from yeast (DY-Pro) and bacteria (MRD-Pro) were assessed for their relative effectiveness in increasing the feed intake rate of Litopenaeus vannamei (ca. 3.00 ± 0.15 g). Ingredients were added to a standard base mix at different levels. Animal protein sources were incorporated at 3% weight as fed, while SCPs sources were incorporated at 3% or 6% weight as fed for DY-Pro or MRD-Pro. Shrimp were stocked into 80 L glass tanks (n= 20 per tank) in a recirculating aquaculture system. Tanks were randomly assigned to one of eight diet treatments (3 tanks/treatment). Experiments measuring the attractibility of each feed were conducted twice daily at 09:00 and 13:30 over a five day period. For each experiment, 40 feed pellets (ca. 1 g) corresponding to the assigned treatment were provided to each tank. To calculate the rate of feed intake, pellets remaining in each tank were counted at six minute intervals for a 72 minute period. Differences in probability of feed intake among diets were evaluated with Cox Regression Analysis.

Under the conditions of this study, the attractability of diets containing 3% squid meal and MRD-Pro were comparable, but both had significantly greater probability of being consumed than diets containing 3% of any other animal proteins tested (Fig.1). The diet containing 6% MRD-Pro had significantly greater probability of being consumed than diet with 3% MRD-Pro. Diet containing DY-Pro had significantly lower probability of being consumed than other animal proteins and MRD-Pro. Results of these trials suggest the use of SCP ingredients can provide additional value based on feed intake and presumed attractability of that ingredient.