DEVELOPMENT OF FEED ATTRACTANT MIXTURES TO INCREASE CONSUMPTION AND REDUCE WASTE IN HIGH-SOY DIETS FOR PACIFIC WHITE SHRIMP Litopenaeus vannamei

Aquaculture feeds, especially those for shrimp, utilize a major proportion of the global production of fish meal. Plant proteins are potential alternatives to fish meal and are increasingly used in aquafeed formulations since they are readily available, economical, and sustainable. However, feeds containing high levels of plant proteins, such as soy, without marine protein additives, have reduced attractability and palatability, negatively impacting performance including feed intake. The goal of our study on Pacific white shrimp, Litopenaeus vannamei, was to identify chemical mixtures that increase the attractability and palatability of feed and thus can substitute for fish meal and other animal protein. Based on results from studies using bioassay-guided fractionation, behavioral testing, and chemical analysis of natural foods of marine crustaceans, we formulated a series of feed attractant mixtures (FAM) of varied composition, complexity, and cost. We tested their efficacy in two laboratory assays, using krill meal as a comparator. An attractability assay measured if group-housed shrimp move toward, probe, and grab the release site of FAM. A palatability assay tested the ability of FAM, when incorporated into feed pellets, to increase the amount of feed ingested. We tested FAM vs. krill meal as additives in three feed formulations that differed in amount of soy plus type and amount of animal protein. Attractability assays showed that FAM alone was highly attractive to shrimp and was effective at 10 μM, and that aqueous extracts of pellets containing FAM could be as attractive as pellets containing krill meal. Palatability assays showed that FAM increased the amount of ingested feed above control levels and was sometimes as effective as krill meal; the magnitude of the enhancement varied with the amount and/or type of animal protein included in the pellets. Our results demonstrate that chemical mixtures can be highly attractive to shrimp, and, when incorporated into high-soy pellets can significantly increase feed palatability. Future directions include optimizing the performance of FAM in pellets, developing formulations with optimal efficacy:cost ratios, and validating these results in grow-out experiments.