سعید خلجی

The aim of this study was the comparative analysis of the chemical composition determined for 45 samples of eggs (white, yolk) from young and old hens of Cobb breeder at 31and 51 weeks of age. Research has been organized in hatchery unit with different age of hen egg production. Determination of gross chemical composition using specific methods in order to standards and regulations in force. Statistical analysis, revealed significant differences between the mean values calculated for albumin, yolk, samples derived from different age breeders. The eggshell, weights were differing significantly between Y and O group breeders. A sample of eggs was used for measurement of chemical composition in the yolk and albumen base on method of AOAC, 1990. There were significant difference (P<0.05) between in egg albumen weights. There were significant difference (P<0.05) among Y and O group in egg yolk weights so in O group egg yolk weight were increased in significant trend. There was no significant differences (P>0.05) between Y and O group in Alb fat, Alb CP, Alb ash, yolk dry matter and yolk nitrogen free extract content, Although yolk dry matter and yolk nitrogen free extract content were decreased in O group compared to Y group numerically. In the present study, a significant effect of breeder age on AlbDM, Yolk fat was observed. This effect indicated that yolk from O group had the more fat content in compare with the Y group, 21.81g and 24.83 % respectively. There was significant differences (P<0.05) between Y and O group in Albumen, energy content, this result may be due to this fact that albumen weight is changed by aging in the egg so energy content of its increased in same manner.