This experiment was designed to evaluate the effect of naked neck (Na) and
frizzle (F) genes on eggshell ultrastructure at different intervals of incubation period. 81
eggshell samples (9 samples/ genotypes/ incubation studied intervals) were taken before
incubation period, at 12 days of incubation period and after hatching. Before incubation
period, the present results showed that the presence of Na or F genes in a single manner
significantly increased the palisade layer compared to normally feathered genotype. The Na
had effected used calcium from mammillary layer during embryonic development .It is well
known that local strains enjoined with higher percentage of fertility. Introducing naked
neck (Na) or frizzle (F) genes did not depress this higher fertility. Moreover, under high
ambient temperature, naked neck and frizzled genotypes recorded higher fertility
percentage than that recorded for normally feathered one. On the other hand, it is noticed
that, naked neck gene decreased hatchability percentage; this may be attributed to the
positive effect of naked neck gene on increasing the length of palisade layer of eggshell
ultrastructure. The decreasing of hatchability associated with naked neck gene was a major
cause that impeded the spread of using this gene in commercial strains. In order to solve
this problem and avoiding the disadvantage of naked- neck gene, it could be beneficial to
insert this gene in a commercial strain and select for a decreased palisade length.