Surreal illustration of a quail in a lab, surrounded by glycine and glutamate molecules, representing sustainable farming.

Unlock the Secret to Healthier Quails: The Power of Glycine and Glutamate

Lena Kashyap in Science & Nature August 2025 • 4 min read.

"Can strategic supplementation improve quail nutrition and reduce environmental impact?"

In the competitive world of poultry farming, producers constantly seek innovative ways to lower costs and boost productivity. Broilers, laying hens, and quails all benefit from strategies that refine their diets for optimal health and growth. One promising approach involves reducing crude protein levels while supplementing with essential amino acids, a concept widely explored in recent research.

The cornerstone of this dietary strategy is the 'ideal protein concept,' where the focus shifts from simply providing high levels of protein to ensuring the right balance of amino acids. This approach promises multiple benefits, including more efficient use of ingredients, improved amino acid profiles, reduced nitrogen and uric acid excretion, decreased heat increment, and ultimately, lower feed costs.

However, the extent to which dietary protein can be reduced remains a subject of debate. While some studies confirm that reducing protein levels by up to four percentage points doesn't harm broiler performance, others suggest that exceeding this threshold can lead to decreased performance and increased carcass fat. New research aims to understand this link between protein reduction and quail health by focusing on glycine and glutamate.

The Science Behind Glycine and Glutamate: Why These Amino Acids Matter?

Surreal illustration of a quail in a lab, surrounded by glycine and glutamate molecules, representing sustainable farming.

Amino acids are the building blocks of protein, essential for various bodily functions. While limiting essential amino acids (those the body can't produce on its own) is a well-established strategy, the role of non-essential amino acids like glycine and glutamate is gaining attention. Here’s a breakdown of why:

Glycine and glutamate are crucial for several metabolic processes. Glycine, in particular, plays a vital role in uric acid metabolism, potentially reducing the need for metabolic synthesis from other amino acids. Understanding how these non-essential amino acids affect quail health is key to optimizing low-protein diets.

Glycine: Important for synthesizing proteins, creatine, and glutathione; helps in detoxification.
Glutamate: Key neurotransmitter in the brain; involved in metabolism and immune function.
Nitrogen Balance: Affecting the nitrogen excretion, both glycine and glutamate have an impact on quail health and environmental effects.
Growth Performance: Supplementing with balanced level, these amino acids impact on overall growth.

A recent study investigated the effects of supplementing L-glycine and L-glutamate in Japanese quails from 1 to 36 days of age. The researchers hypothesized that reducing crude protein levels while strategically adding these amino acids could optimize quail performance and reduce nitrogen excretion. By exploring different dietary combinations, the study aimed to refine the ideal protein concept for quail nutrition.

Key Findings: What Does This Mean for Quail Farming?

The study reveals valuable insights into quail nutrition and the potential of strategic amino acid supplementation. While the addition of L-glutamate and L-glycine in quails based on the ideal protein concept is not necessary, the dietary addition of L-glycine reduces nitrogen excretion. This information paves the way for more sustainable and cost-effective quail farming practices.

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This article is based on research published under:

DOI-LINK: 10.1111/jpn.13010, Alternate LINK

Title: Supplementation Of L‐Glycine And L‐Glutamate To Japanese Quails From 01 To 36 Days Of Age Using The Ideal Protein Concept

Subject: Animal Science and Zoology

Journal: Journal of Animal Physiology and Animal Nutrition

Publisher: Wiley

Authors: Danilo V. G. Vieira, José H. V. Silva, Fernando G. P. Costa, Thiago S. Melo, Matheus R. Lima, Danilo T. Cavalcante, José G. De Vargas Júnior, Talita P. Bonaparte, Lorena C. Oliveira

Published: 2018-11-07

Everything You Need To Know

What is the 'ideal protein concept' and how does it relate to quail nutrition?

The 'ideal protein concept' in quail nutrition focuses on balancing amino acids rather than just providing high levels of protein. This approach aims to improve ingredient use, amino acid profiles, reduce nitrogen and uric acid excretion, decrease heat increment, and lower feed costs. While dietary protein reduction is beneficial, research explores the limits to avoid decreased performance and increased carcass fat.

Why are glycine and glutamate considered important in quail diets, even though they are non-essential amino acids?

Glycine and glutamate are crucial because of their roles in various metabolic processes. Glycine is important for uric acid metabolism and the synthesis of proteins, creatine, and glutathione. Glutamate serves as a key neurotransmitter and is involved in metabolism and immune function. These non-essential amino acids also affect nitrogen excretion, overall quail health, and growth performance.

What do recent findings suggest about supplementing L-glutamate and L-glycine in quails, and how does this impact quail farming practices?

The study's findings indicate that while supplementing L-glutamate and L-glycine based on the 'ideal protein concept' is not essential, the dietary addition of L-glycine reduces nitrogen excretion. This suggests that strategic supplementation of L-glycine could lead to more sustainable and cost-effective quail farming practices by minimizing environmental impact without compromising quail health or productivity.

How does nitrogen excretion affect quail farming, and what role does L-glycine play in managing it?

Nitrogen excretion affects quail farming in several ways. High nitrogen excretion contributes to environmental pollution and can impact quail health. By strategically supplementing diets with amino acids like L-glycine, quail farmers can reduce nitrogen waste, leading to more environmentally friendly and sustainable practices. Further research could explore how different levels of L-glycine affect other aspects of quail physiology and productivity.

Besides glycine and glutamate, what other nutritional considerations are important for quail health and diet optimization?

While the study focused on L-glycine and L-glutamate, other amino acids also play significant roles in quail health and nutrition. Essential amino acids, which quails cannot produce themselves, must be adequately supplied in their diet to support growth, immune function, and overall well-being. Future research could explore the synergistic effects of combining various amino acids to further optimize quail diets and reduce the reliance on high crude protein levels, potentially unlocking new strategies for sustainable quail farming.