A trial was conducted to evaluate the replacement efficacy of regular oyster shell (ROS) with mine oyster shell (MOS) on the performance of 240, 44-weeks Hy-Line W-36 laying hens for 3 periods of 28 days. In a randomized complete block design with 5 treatments and 4 replicates as blocks, 5 levels of 0.0, 25.0, 50.0, 75.0 and 100.0 % MOS were replaced with ROS based on their calcium contents. Diets were formulated as Hy-Line manual recommendation for 44-58 weeks laying hens. Feed intake, hen day and hen housed egg production, egg weight, shell weight, shell thickness, number of broken and cracked eggs and specific gravity of the random sample eggs were recorded at their appropriate times. Hen day and hen housed egg production significantly decreased (P<0.0.5) as the ratio of MOS in the diets increased. The effect of MOS on shell thickness and specific gravity were significantly increased (P<0.05) and the highest values for both traits were for 25% MOS + 75% ROS. The lowest incident of broken eggs was for 25 and 100% replacement of MOS. Under the conditions of this study, it was concluded that MOS might be a suitable calcium source for laying hens when a better egg quality is concern.

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