These investigations were intended to identify the influence of parental flock age at heavy hybrid Ross 308 (usage period) on more important reproductive capabilities (carrying eggs intensity of brood eggs,egg mass, one day old chick mass, relative chick mass share in complete egg mass) and consumption of food per processed – hatched chicken (final product of production cycle). Flock usage period lasted for 40 weeks (all eggs), respectively, 38 (brood eggs) weeks and there was possibility, based on achieved results, with evaluation of phenotype correlation, to get some concrete conclusions about the age influence on analyzed parameters during mentioned flock rising period. Phenotype correlationamong investigated characteristics has been identified since second half of parental flock using period, since 41st week age (20th carrying eggs week) up to the end of production process when parental flock was 61 week old (41st egg production week). Flock age has statistically important positive (P < 0.05) influence on carrying eggs intensity of brood eggs until 49st week (rp = 0.391) and on percentage of chicken feasibility regard the complete number of inputted eggs until 50th week (rp = 0.434). There wasstatistically significantly increasing of egg mass and one-day old incubated chicken mass (P < 0.001) as parental flock was older. Complete correlation connectivity has been identified between egg mass and absolute chick mass (P < 0.001), while very strong (P < 0.001) or strong (P < 0.01) correlative connectivity between egg mass and relative chick share [(chicken mass/egg mass) x 100]. Further more, we determined negative correlation between eggs age and food consumption per hatchedchicken for all time of breeding broiler parents, except 61st week when we determined positive coefficient of phenotype correlation (rp = 0.062), but statistically inconsequent
