This study evaluated the effects of midnight feeding, limestone particle size, and graded reductions in dietary calcium concentration on production performance, egg quality, and tibia characteristics in laying quails. A total of 1200 birds were allocated to a 2 × 2 × 3 factorial arrangement including midnight feeding or no midnight feeding, coarse or fine limestone, and three dietary calcium levels (0%, 10%, and 20% reduction). Midnight feeding did not affect egg production, egg weight, feed conversion ratio (FCR), or egg quality traits in either sampling period. Limestone particle size did not influence production or eggshell parameters, but quails receiving coarse particles exhibited significantly longer tibiae compared with those fed fine particles. Reducing dietary calcium by up to 20% did not impair egg production or major shell traits, although a tendency toward reduced tibia breaking strength indicated increased skeletal sensitivity to calcium restriction. A significant interaction between midnight feeding and particle size was detected for specific gravity in the first sampling period, while interactions among dietary factors were otherwise limited. Overall, laying quails maintained stable performance, egg quality, and bone mineral composition across the evaluated feeding schedules, particle sizes, and calcium concentrations, suggesting that the tested nutritional conditions were adequate to support productivity and skeletal development.

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