Comparative study of two, for the marketing most important, egg quality parameters (egg weight and egg shell strength) in two genotypes of commercial laying hens was realized. Egg production, egg weight (size) and egg shell strength in ISA Brown (14,879) and DeKalb White (15,376) layers, housed in battery cages under similar in-house environment and feed complete mixtures according the technological nutrient recommendation, were followed through the laying cycle. Egg weight and egg shell

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... h were analyzed in the Laboratory for testing egg quality using Egg shell Gauge (Robotmation Co. Ltd., Tokyo, Japan), computerized equipment that perform unbiased, shell breaking strength values. Both genotypes have high egg production that was close to the technological level of laying. No differences in egg number/hen housed were noticed. DeKalb White layers produce on average 1 g bigger eggs than the ISA Brown line layers (64.18 g vs 63.17 g), resulting in better feed to egg mass conversion. ISA Brown layers produce eggs with stronger egg shell (3864.52 g/cm 2 ) compared to DeKalb White genotype (3575.78 g/cm 2 ). High summer temperature influence the strength of the egg shell in both genotypes, resulting in lower strength compared to average egg shell strength values.