Evaluation of the performance and gene expression of two strains of Japanese quail following supplementation with frankincense and Melissa officinalis.

This study evaluated the effects of dietary supplementation with frankincense (FR) and Melissa officinalis (MO) on growth performance, meat quality, economic efficiency, and the expression of growth-, immunity-, and antioxidant-related genes in two strains of Japanese quail. A total of 300 fourteen-day-old female quails (150 brown, 150 white) were assigned to five treatments per strain: a control, two FR levels (10 and 12 g/L drinking water) and two MO levels (2.5 and 3 mL/L drinking water), in a completely randomized design with a 2 × 5 factorial arrangement for 28 days. Results revealed a significant treatment × strain interaction, indicating a strain-dependent response. In the brown strain, 10 and 12 g/L FR produced the most favorable responses, whereas in the white strain, 10 g/L FR and 3 mL/L MO were the most effective, resulting in improved growth performance and economic returns. At the treatment level, 10 g/L FR and 3 mL/L MO enhanced body weight, feed efficiency, dressing percentage, and economic indicators. These improvements were associated with upregulation of IGF-1, GPX1, and IL-6, along with downregulation of MSTN. At the strain level, the white strain outperformed the brown strain in productive traits and showed higher IGF-1 expression with lower MSTN levels, whereas the brown strain exhibited relatively stronger GPX1 and IL-6 expressions. Therefore, these findings indicate that the effectiveness of phytogenic feed additives is strongly influenced by genetic background, highlighting the importance of optimizing both treatment level and strain selection to maximize productive performance, meat quality, and economic efficiency in Japanese quail. Specifically, FR at 10-12 g/L is recommended for brown quails, whereas 10 g/L FR or 3 mL/L MO is more suitable for white quails.