Abstract
This trial was conducted to evaluate the effects of high-dose daidzein supplements on laying performance, egg quality and antioxidation in laying hens during the late laying period. Seven hundred sixty eight 55-wk-old Hyline Brown were randomly assigned to four groups with 8 replicates of 24 birds each (192 laying hens per group) and fed diets supplemented with 0 (control), 10 mg/kg, 50 mg/kg and 100 mg/kg daidzein for 8 wk in the diets. Egg production, egg mass, feed conversion and egg yolk malondialdehyde were significantly effected by daidzein supplementation (P<0.05), while there are significant quadratic correlations between average egg production/egg mass/feed conversion/ egg yolk malondialdehyde and daidzein supplementation (quadratic P=0.022, 0.003, 0.021 and 0.002; respectively). The optimal daidzein supplementation in the diet of laying hens during the late laying period for maximum egg production, egg mass, feed conversion and egg yolk malondialdehyde were 72 mg/kg, 48.5 mg/kg and 56.34 mg/kg and 51.43 mg/kg. Daidzein supplementation significantly improved three calcium-related egg quality indexes (eggshell thickness, eggshell percentage and eggshell strength; P<0.05) and egg yolk total superoxide dismutase (P<0.05), linearly. These findings indicated that the daidzein could be a very effective additive to improve laying performance and eggshell quality in the birds during the late laying period, even though the dose of it was high.
