A study was conducted to determine whether dietary chromium (1200 μg Cr/kg diet) and vitamin C (300 mg/kg) attenuate the adverse effects of heat stress on external and internal egg quality traits in Japanese quails. A total of 160 female and 64 male Japanese quails were randomly assigned to 4 treatment groups (4 replicates with 14 birds each; 10 females and 4 males) in a completely randomized design with a 2 × 2 factorial arrangement. Dietary treatments were: 1) basal diet (control; NRC recommendation), 2) basal diet supplemented with 1200 μg Cr/kg diet (Cr), 3) basal diet supplemented with 300 mg VC/kg diet (VC), and 4) basal diet supplemented with 1200 μg Cr plus 300 mg VC/kg diet (Cr-VC). After a 2-week adaptation to the diets, the birds were exposed to 36°C for 6 h/day (from 10 am to 4 pm) for a 5-wk-long period. Results showed that Cr-VC increased the egg weight and decreased the shape index (P< 0.01). The shell breaking strength and specific gravity of egg was not affected by the treatments (P> 0.05). Shell weight was increased in VC and Cr-VC groups with an increased egg shell thickness for the latter group (P< 0.05). Diets supplemented with Cr and vitamin C tended to maintain yolk color (P< 0.01), albumen weight (P< 0.01) and yolk weight (P< 0.05) better than with other dietary groups. Yolk index and albumen index, however, were not affected by dietary treatments (P> 0.05). Data suggested that supplementing the diet with 300 mg VC/kg and 1200 μg Cr/kg or their concurrent use improved external and internal egg quality traits, making them as an alternative to the current approaches to ameliorate the adverse effects of heat stress in laying quail production.

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