Effects of Dietary Granular Ark Shell Partially Replacing Limestone on Laying Performance and Eggshell Quality in Aged Hens

This experiment was conducted to examine the dietary effects of local granular ark shell(GAS) replacing limestone on egg shell quality in aged hens. A total of 200 Hy-Line Brown layers of 54-weeks-old were allotted into four treatments with five replications each. They were fed control(limestone only) 1% GAS, 2% GAS and 3% GAS diets for 6 weeks. GAS was substituted for coarse-type limestone at 0, 1, 2 or 3% of diet on weight basis. Particle sizes of limestone and GAS were within the ranges of 2~4 mm in diameters. In vitro HCl solubility of GAS was significantly lower(6.27 vs. 7.90%) compared to that of limestone(p