Interpretive Summary: Dietary glycine supplementation improves the growth performance of 110- to 240-g (phase II) hybrid striped bass (Morone saxatilis ♀× Morone chrysops ♂) fed soybean meal-based diets
By: Wenliang He, Xinyu Li, Guoyao Wu
Glycine is the simplest but the most abundant amino acid in the bodies of animals including fish and pigs. The content of glycine in plant-sourced feedstuffs (e.g., soybean meal) is generally low. Glycine can be synthesized de novo in all animals and, therefore, has traditionally been classified as a nutritionally nonessential amino acid for fish and mammals. However, a capacity for the synthesis of glycine does not necessarily mean its adequate formation by animals. Growing evidence shows that either neonatal pigs fed milk protein-based diets or postweaning pigs regardless of their birth weights do not synthesize sufficient glycine, and must ingest supplemental glycine (e.g., 1% in diets) for optimum growth performance. Similar results have been reported for 5- to 40-g (phase I) juvenile hybrid striped bass (HSB) fed and largemouth bass fed soybean meal-based diets. The present study tested the hypothesis that supplementing glycine to soybean meal-based diets may enhance the growth of 110- to 240-g (phase II) HSB. Results of the current investigation indicate that glycine is also inadequate for normal intestinal structure or maximum growth in phase II HSB fed soybean meal-based diets. Supplementing 1% or 2% glycine to these diets increased protein accretion, weight gain, and feed efficiency in HSB while improving their intestinal structure. These findings indicate an important role for a sufficient provision of dietary glycine in the optimal nutrition, health, and growth of finishing HSB, and have broad implications for developing low-fishmeal diets to enhance fish production and sustain animal agriculture (including aquaculture).
Read the full article in the Journal of Animal Science.