Poultry breeding farms are facing the problem of decreasing reproductive function of seed male birds that results in their culling. The purpose of the research is screening of male birds’ sperm. The results of the research done on the native sperm have shown the following changes: an increasing number of the defected sperm – 58% (normally 5%); decreasing germinating power of sperm – 51% (normally 70%); content of normal sperm – 39.4% (normally 90%), that means low quality of the sperm resulting in decreasing hatchability. Microbiological research done on the sperm have discovered opportunistic pathogenic microflora: Stenotroph.meltophilia (100%) and Candidasp. (80%) while the norm is not more than 10%. The results of electron microscopy of the sperm have shown swelling of mitochondria, clearing of matrix, and partial or total destruction of crista. Some sporadical sperm have been identified, such as: the ones with binominal spermatic filaments, in the state of high-grade destruction, and with abnormalities, whereas cytoplasm vacuolation, granularity of chromatin and abnormality of spermatic filaments have been identified. Such sperm with exaggerated sperm necks cannot penetrate an egg membrane and range and speed are influenced in a negative way. The main reason for alteration of mitochondria is connected with negative changes in ATF production. The II type of swelling mitochondria caused by increased penetration of inner membrane has been identified. When the content of calcium sparks exceeds the norm, they penetrate mitochondria and form the precipitate of calcium phosphate that results in nonreversible calcification of mitochondria, damage of inner and outer membranes, and destruction of mitochondria.