Effect of ascorbic acid and sodium bicarbonate supplementation in diets with two energy levels on the performance of laying Japanese quails during extreme dry summer

An experiment was conducted involving laying quails (n=120) during 22–34 weeks of age to evaluate the optimum dietary energy concentration and effect of additives (ascorbic acid and sodium bicarbonate) on egg production under heat stress. Six dietary treatments with two levels of energy (2900 kcal and 2600 kcal ME/kg) and two additives (ascorbic acid @ 300 mg/kg and sodium bicarbonate @ 1% in diet) at each energy level were formulated following 2x3 factorial design. Each dietary treatment was assigned to 20 quails caged individually. The temperature in house during the experimental period was minimum 31.1 to 37.1°C (mean 33.1±0.13°C) and maximum 33.1–40.5°C (mean 36.4±0.19°C). Overall egg production, egg-weight and feed conversion efficiency did not differ due to dietary energy levels or additive supplementation. The daily feed intake was significantly lower (P <0.02) in the ascorbic acid supplemented group in comparison to the unsupplemented group (control). The interaction between energy and additive supplementation for per cent egg production was significant with lowest egg production (74.8%) in group containing 2900 ME kcal/kg and 1% sodium bi carbonate. The maximum mortality occurred in the sodium bicarbonate supplemented groups (40% in high energy and 45% in low energy group) and lowest in the ascorbic acid supplemented group (15%). Shape index, albumen index and shell weight (as % of egg weight) did not differ due to any variable. Shell thickness was higher (P<0.04) in layers at low energy level or ascorbic acid (P<0.07) group. Yolk index was better (P<0.03) in high-energy diet. Ascorbic acid supplementation improved the yolk index, while bicarbonate decreased (P<0.07) yolk index. Internal quality unit (IQU) differed due to the interaction of energy and additives. The study indicated that a dietary level of 2900 kcal ME/kg with ascorbic acid supplementation might be beneficial for optimum egg production performance and better survivability of quail layers during heat stress