Interactive Effects of Dietary Crude Protein and Methionine Levels on Growth Performance, Carcass Quality and Blood Biochemistry of Japanese Quail During Starter and Grower Phases.
- 1Department of Animal Science, Ta.C., Islamic Azad University, Tabriz, Iran.
- 2Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
- 3Department of Animal Science, Shab.C., Islamic Azad University, Shabestar, Iran.
Abstract
Background
This study evaluated the interactive effects of dietary crude protein (CP) and methionine (Met) on growth performance, carcass traits, blood biochemistry, thyroid hormones and liver enzymes in Japanese quail during the starter (0-14 days) and grower (14-35 days) phases.Methods
A total of 1,350 mixed-sex chicks were used in a completely randomised 3 × 5 factorial design, testing three CP levels (22%, 24%, 26% of diet starter; 21%, 23%, 25% of diet grower) and five Met levels (0.30%-0.70% of diet). Performance traits, carcass characteristics, blood indices, thyroid hormones (T3 and T4) and liver enzymes (AST and ALT) were measured, and nonlinear regression models were used to estimate optimal Met requirements.Results
Raising starter-phase CP to 26% significantly improved weight gain (+4.1%), feed conversion ratio (-4.1%), and carcass yield (+1.5%). Methionine supplementation up to 1.30% further enhanced these traits, with optimal Met levels ranging from 0.50%-0.70% depending on CP concentration. In the grower phase, the combination of 25% CP and 1.30% Met produced the highest male weight gain (161.84 g) and breast yield (29.88%), while females showed the highest breast yield (30.90%) at the same levels, indicating sex-specific responses. Increasing Met reduced blood glucose, triglycerides, and cholesterol while raising HDL, with most blood parameters showing significant CP × Met interactions. Thyroid hormones rose with higher CP, though T3 declined with Met supplementation; both factors also influenced liver enzyme activity.Conclusions
These findings confirm a synergistic relationship between dietary protein and methionine, supporting 24%-26% CP with 0.50%-0.70% Met in the starter phase and 23%-25% CP with appropriate Met levels in the grower phase for modern quail strains-offering updated recommendations beyond the older Nutrient Requirement Council (NRC) guidelines for commercial production.
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BibTeX
@article{pirozmaleki2026interactive,
title = {{Interactive Effects of Dietary Crude Protein and Methionine Levels on Growth Performance, Carcass Quality and Blood Biochemistry of Japanese Quail During Starter and Grower Phases.}},
author = {Elyas Piroz-Maleki and Mehdi Taginejad-Rodbaneh and Ruhollah Kianfar and Sima Moghaddaszadeh-Ahrabi and Abolfazl Ghorbani},
journal = {Veterinary medicine and science},
year = {2026},
month = oct,
doi = {10.1002/vms3.71301},
url = {https://europepmc.org/article/MED/42949839},
note = {CC BY},
}
RIS
TY - JOUR
TI - Interactive Effects of Dietary Crude Protein and Methionine Levels on Growth Performance, Carcass Quality and Blood Biochemistry of Japanese Quail During Starter and Grower Phases.
AU - Elyas Piroz-Maleki
AU - Mehdi Taginejad-Rodbaneh
AU - Ruhollah Kianfar
AU - Sima Moghaddaszadeh-Ahrabi
AU - Abolfazl Ghorbani
PY - 2026
DA - 2026/10/28
JO - Veterinary medicine and science
DO - 10.1002/vms3.71301
UR - https://europepmc.org/article/MED/42949839
AB - Background This study evaluated the interactive effects of dietary crude protein (CP) and methionine (Met) on growth performance, carcass traits, blood biochemistry, thyroid hormones and liver enzymes in Japanese quail during the starter (0-14 days) and grower (14-35 days) phases.Methods A total of 1,350 mixed-sex chicks were used in a completely randomised 3 × 5 factorial design, testing three CP levels (22%, 24%, 26% of diet starter; 21%, 23%, 25% of diet grower) and five Met levels (0.30%-0.70% of diet). Performance traits, carcass characteristics, blood indices, thyroid hormones (T3 and T4) and liver enzymes (AST and ALT) were measured, and nonlinear regression models were used to estimate optimal Met requirements.Results Raising starter-phase CP to 26% significantly improved weight gain (+4.1%), feed conversion ratio (-4.1%), and carcass yield (+1.5%). Methionine supplementation up to 1.30% further enhanced these traits, with optimal Met levels ranging from 0.50%-0.70% depending on CP concentration. In the grower phase, the combination of 25% CP and 1.30% Met produced the highest male weight gain (161.84 g) and breast yield (29.88%), while females showed the highest breast yield (30.90%) at the same levels, indicating sex-specific responses. Increasing Met reduced blood glucose, triglycerides, and cholesterol while raising HDL, with most blood parameters showing significant CP × Met interactions. Thyroid hormones rose with higher CP, though T3 declined with Met supplementation; both factors also influenced liver enzyme activity.Conclusions These findings confirm a synergistic relationship between dietary protein and methionine, supporting 24%-26% CP with 0.50%-0.70% Met in the starter phase and 23%-25% CP with appropriate Met levels in the grower phase for modern quail strains-offering updated recommendations beyond the older Nutrient Requirement Council (NRC) guidelines for commercial production.
SN - 2053-1095
ER -