Effect of Dietary Level of DL-Methionine on Growth Performance and Some Blood Parameters in Japanese Growing Quails

One-day-old Japanese quail birds totaling 900 were divided into five groups, with six replicates in each group. Five doses of DL-methionine supplementation were used in a one-way arrangement for the experimental treatments. At concentrations of 0.0, 0.9, 1.65, 2.15, and 2.65 g/kg feed, DL-methionine was included in a basal diet. Dietary methionine values ranged from 0.41 (inadequate), to 0.50 (sufficient; 100% NRC), to 0.58, 0.63, and 0.68 (excess), compared to the current NRC standards. Dietary methionine levels did not significantly affect performance at 32 days of life. DL-methionine has no significant effect on total protein, albumin, globulin, creatinine, uric acid, total antioxidant capacity (TAC), or malondialdehyde (MDA). In contrast, serum high-density lipoprotein (HDL-c) levels significantly increased (P ≤ 0.05) in response to DL-methionine supplementation, and serum immunoglobulin G (IgG) levels significantly varied between groups (P ≤ 0.05) in response to DL-methionine supplementation, with the highest level occurring at 0.68% (exceeding) the NRC (1994) recommended concentration. Our findings imply that production performance, immunity, or antioxidant status can be improved by dietary supplementation with DL-methionine levels at 0.68% (excess) of the NRC (1994) recommended levels. However, a high methionine intake has a beneficial impact on enhancing serum HDL levels.