AN IMPACT OF BREEDER FLOCK AGE (review) Yu. <...> Fuchika, Balashikha, Moscow Province, 143900 Russia, email zabudsky@hotmail.com Received February 1, 2016 A b s t r a c t For the first time recent findings on reproductive function in poultry as influenced by breeder age are summarizes and discusses in Russian. <...> The focus is on changes in incubation eggs, metabolism, growth and development of the chicken at pre- and postnatal ontogenesis. <...> In 511 breeder flocks from the Netherlands in 2004-2006 (7.5 million eggs, over 24,000 batches) the breeder age has been proved to be dominant for hatchability compared with the environment conditions and poultry genotype (H. Yassin et al., 2008). <...> When aging, the breeders lay eggs bigger in size with an increased yolk to albumen percentage. <...> Shell quality becomes significantly worse, including loss in thickness and strength (P.P. Tsarenko et al., 2012). <...> The egg weight loss in the course of incubation is inversely proportional to the shell thickness. <...> For older breeders the metabolic heat produced by embryo increases, and an increased egg shell permeability can lead to bacterial contamination (A. Rodrнguez-Navarro et al., 2013). <...> There is a parabolic change in main indicators of hen reproductive function when aging. <...> In the chickens hatched from the eggs laid at the end of laying period a probability of microbial infection increases due to underdeveloped navel (H. Yassin et al., 2009). <...> Due to the differences in embryo growth and development for young and old breeders, the eggs should be pre-sorted prior to incubation with regard to egg weight and breeders’ age to provide uniform adaptiveness in the progeny. <...> Keywords: poultry, breeder flock age, eggs, incubation, embryo metabolism, incubation mode, quality of chicks Blood concentrations of luteinizing and follicle-stimulating hormones are decreased in laying hens with advancing age. <...> Similar changes are observed in the concentrations of progesterone and estradiol in the beginning, middle, and at the end of the egg production period, i.e., respectively, 4.3, 3.8, 1.6 ng/ml and 184.9, 181.7, 66.7 pg/ml [3]. <...> The number of yellow follicles is 436 higher in young pullets than in old hens [4]. <...> The major characteristics of hatching <...>