Experiment with three groups of «Hisex brown» hens cross from 20 to 68 weeks of age has carried out. Hens received a standard diet PC 1-18. The diets of the 1st, 2nd and 3rd group hens were supplemented by 9% limestone with particle size of 1, 2 and 3 mm, respectively. On average, egg weights during the experiment in of 2nd and 3rd groups were 3.26 and …