**5. Conclusion**

Based on the research undertaken with an aim to establish effects of the light line hybrid ISA Brown parent flock's age on incubation values of eggs (fertilization and chick hatchability) and morphometric indicators (pre incubation egg mass, length, width, and egg shape index, absolute and relative egg mass loss until day 18 of incubation, hatched chicken mass and relative share of the chick in the egg mass) and their possible effects on the sex of the hatched chicks, two conclusion can be made. First, in comparison with the older flock (OF49), the younger flock (YF33) demonstrated better incubation values of eggs, and all its morphometric indicators were lower, with the exception of the egg shape index which was statistically significantly greater (P < 0.001) by 1.46% in the YF33. Second conclusion is that the eggs which hatched female chicks (YF33 + OF49) had lower values of observed morphometric traits than those with male chicks, except the egg shape index.
