Abstract
The present study aimed to assess the effect of dietary supplementation of DL- Methionine

(DL-Meth) on growth performance and health of growing Japanese quails. A total of 300, 2-

week-old quails were randomly divided into 4 equal experimental groups, with 8 replicates of

10 quails per pen, for 4 weeks. Quails in the control group were fed a control diet whereas in

the other experimental groups the quails were fed a diet supplemented with DL-Meth (0.99%)

at 1, 3, and 5g/kg diet. Quail’s performance traits in each experimental group were calculated

weekly. At the end of the growth period, eight quails (one/replicate) from each group were

chosen randomly for serum collection, carcass attributes measurement. The results revealed that

quails’ growth traits; final weight (FW), weight gain (WG), and feed conversion ratio (FCR)

showed a significant improvement (p < .05) (linear) as DL-Meth supplementation level

increased to 3 and 5g/kg diet (7.2 and 9.1g/kg Meth respectively). Serum superoxide dismutase

and catalase activities were improved (p < .05) in quails fed DL-Meth supplemented diet at 3,

and 5g/kg. DL-Meth supplementation at 3, and 5g/kg was associated with a significant (p < .05)

increase in quails’ breast muscle percentages compared to the other groups. In addition, the

sensory evaluation of meat was not influenced by supplementation of methionine at different

levels. It is concluded that under our experimental conditions, supplementation of 3g/kg DL-

Meth (methionine content, 7.2g/kg) to corn-soybean meal-based diet for Japanese quails, was

appropriate for enhancing the birds’ growth, breast muscle yield, and antioxidant activity with

maintaining the acceptable sensory quality of birds’ meat.

Key words: 38 Japanese quails, DL-methionine, growth performance, carcass attributes, antioxidative stress.