On the other hand, due to the ability of humates to bind materials in certain environments and to release these materials under different environmental conditions (Shermer et al., 1998), dietary HS may prevent reduction in egg production and egg shell quality after peak laying period. Therefore, more information is still needed about the effect of HS on egg shell quality and egg production after peak period. The objective of the study was, therefore, to investigate effects of dietary HS on laying performance and some egg shell quality parameters after peak laying period.