Abstract
The aim of this study was to investigate the effect of artificial moulting on some egg shell quality parameters of produced eggs from two genotypes of aged laying hens. The experiment was conducted on group 1 ISA Brown 88 weeks old and group 2 Hisex Brown 91 weeks old hens. The egg weight during the period of starvation until the stopping of laying was higher in ISA Brown hens (64.38 g) and lower in Hisex Brown (59.46 g) (p<0.05). During the preparing and second laying cycle there were also significant difference in egg weight (p<0.05).The shell weight of the experimental strains (ISA Brown and Hisex Brown) significantly decreased during the period of stress (p<0.01) and significantly increased in the second egg laying cycle in comparison with the stress period (p<0.01). Feed restriction significantly interacted with egg shell quality characteristics. The differences of shell weight between two strains were significant in the all 3 points of the experiment (preparing period, stress period and second egg lying cycle). The same situation was found in the shell percentage, shell thickness and shell ash compared in experimental periods of rejuvenation. In these three mentioned characteristics there were found significant changes: between the stress and the other periods, preparing and stress period, second egg laying and stress period (p<0.01). But there were not found differences between the strains of layers, it means that their performances are nearly the same (p>0.05).
