Plant-Based Diets and Nutritional Strategies for Improving Growth and Health of Marine Species

Abstract

The rising cost and limited supply of fish meal (FM) have created sustained pressure on the marine aquaculture industry to develop practical diet formulations for high-value species that reduce or eliminate dependence on wild-caught fish protein without compromising production performance. This dissertation addresses that challenge through five studies examining alternative protein ingredients and amino acid (AA) supplementation strategies in juvenile Florida pompano (Trachinotus carolinus) and Pacific white shrimp (Litopenaeus vannamei), two commercially significant species in United States marine aquaculture. The first two studies evaluated protein ingredients in FM-free practical diets for Florida pompano. Modified soybean meal (SBM) variants, low-oligosaccharide SBM (LO-SBM) and enzyme-treated SBM (ET-SBM), were compared against conventional solvent-extracted SBM (SE-SBM) across graded inclusion levels, and corn fermented protein (CFP), a high-protein co-product of the corn-based dry-mill ethanol industry, was evaluated as a replacement for SBM alongside its residual Saccharomyces cerevisiae yeast fraction. A parallel study extended the CFP evaluation to Pacific white shrimp, testing two commercial CFP sources as partial substitutes for SBM at graded inclusion levels in FM-based practical diets. The final two studies addressed AA nutrition in Florida pompano. The first assessed growth, metabolic, and immune responses to graduated dietary glycine supplementation in FM-free practical diets. The second determined the dietary arginine (Arg) requirement using a crystalline AA dose-response approach, with the practical aim of establishing whether conventional, lower-cost protein ingredients already supply enough Arg to support growth without added crystalline Arg. Across all studies, FM-free and low-FM diets built on SBM, poultry meal, corn protein concentrate, and CFP supported commercially acceptable growth and health in both species. Anti-nutritional factor reduction through selective breeding or enzymatic hydrolysis did not confer measurable advantages over conventional SE-SBM in pompano, and CFP supported inclusion levels up to 20% of diet in pompano and 15 to 16% in shrimp without impairing production performance or gut health. Glycine supplementation did not enhance growth or immune function in pompano under standard rearing conditions, though metabolic effects on hepatic indices appeared at higher levels. The Arg study found no growth response across the tested range, indicating that the requirement of juvenile Florida pompano is met at or below 2.32% of diet (5.66% of dietary protein). Poultry meal and plant protein ingredients therefore supply adequate Arg on their own, so crystalline Arg supplementation is unnecessary in these practical diets within the tested range, allowing formulators to rely on lower-cost ingredients. Together, these findings show that commercially viable FM-free and low-FM diets for Florida pompano and Pacific white shrimp are achievable with currently available domestic ingredients, and they establish species-specific nutritional parameters that strengthen the foundation for precision diet formulation in marine aquaculture production systems.