A study was conducted to investigate the effects of different betaine (BET) (0.0, 0.5 or 1.0 g/kg) and folic acid (FA) (0.0, 4.0 or 8.0 mg/kg) levels on performance, egg FA concentration and egg production of laying quails using 288 forty-two day-old Japanese quail in a 3 × 3 factorial arrangement of treatment based on randomized complete design. The results showed that none of the performance ...