EN
Our objective was the identification of chimerism on the basis of some traits and the estimation of their effect on reproductive features. The investigation was conducted on 11 cocks of Zk (donor) breed, 10 WI cocks (blastoderm cells recipient) and 10 chimeric (Ch) cocks, raised and housed in the same environmental conditions. Chimerism was identified on the basis of different criteria: down color, germline chimerism (backcrossing), and blood chromosome W identification (PCR). Using the MultiScan software the concentration of spermatozoa in sperm from cocks of 23, 28 and 34-weeks-of-age was determined. From the data presented in this manuscript, it is evident that the production of the chicken chimeras using the blastodermal cells is not a one-off event. On the contrary 90% (9/10) of investigated cocks were identified as chimera. Three chimeras produced the low spermatozoa sperm concentration (from 653.000 to 772.000 /ml), and two chimeras did not produce sperm. Among the above-mentioned cocks, some had underdeveloped testis and others showed chromosome W in their blood. On the other hand, three chimeras produced a high number of spermatozoa (from 2. 289.000 to 2. 681.000 / ml) and two of them were characterized by the highest spermatozoa production in comparison with all 31 investigated Wl, Zk and Ch cocks.