Interpretive Summary: Glycine nutrition and biochemistry from an aquaculture perspective

By: Blaine A Suehs, Delbert M Gatlin, III, Guoyao Wu

Implications

• Glycine is a functional amino acid that serves in numerous essential physiologic and metabolic processes.
• Additional supplementation of glycine in the diet of aquatic species has been shown to impart beneficial effects.
• Future research should evaluate the biochemical mechanisms associated with glycine nutrition in fish.

Aquaculture represents the fastest-growing farmed food sector globally, surpassing total capture fisheries at approximately 90 million tons for human consumption (FAO, 2022). However, due to the rapid increase of farmed fish production to meet the protein demands of an increasing world population, marine feedstuffs (fishmeal and fish oil) are now considered finite resources and are transitioning to strategic ingredients in the diets of most carnivorous fish, and are largely omitted in the diets of omnivorous species such as Nile tilapia and channel catfish except in early life stages. This limited supply and increased demand has created a unique inequality in the market of these marine raw materials, as the 2023 price of fishmeal and fish oil exceeded USD 1,800/ton and USD 3,000/ton, respectively (FAO, 2022). As the price of marine protein and oils has increased dramatically, plant and animal byproducts have become foundational ingredients in aquatic diets for carnivorous and omnivorous fish species alike. Although plant-derived feedstuffs do have some negative characteristics, such as antinutritional factors and inadequate amino acid (AA) profiles, plant-protein feedstuffs (such as soybean meal, SBM) have become primary contributors to crude protein in many diets due to their relatively high protein content and marginal price. However, nutritionists must be cognizant of AA concentrations in diets with high inclusion levels of plant-protein feedstuffs to prevent AA deficiencies in fish.

Read more in Animal Frontiers.