Abstract
Hatching eggs used in the study were obtained from commercial broiler breeders: Cobb, Ross 308 and Arbor Acres. A total of 150 hatching eggs were obtained from each breed at age, 30-35, 40-45 and 50-55. Eggs for each age were randomly divided into three experimental group, 50 eggs (replicates) in each, stored either for 0, 7 or 14 days under 75-80% relative humidity and 16-18 degrees C and incubated following standard hatchery practices. Eggs were candled at the end of the first week and 18th day of incubation period to determine percentages of fertile eggs and early and late embryonic mortality. Hatched chicks number was recorded to determine hatchability of fertile and total eggs and unhatched eggs were broken to verify early and late embryonic mortality. Data were statistically analyzed using the General Linear Models procedures of SAS described in the material and methods. The results indicate that breed and age had a significant (P <= 0.01) effect on most studied traits. Cobb showed the best values in all studied traits followed by Ross and Arbor Acres. Young breeders had significantly (P <= 0.05) better performance with regard to fertility and total eggs hatchability, whereas fertile hatchability and late and total embryonic mortality were the lowest for young and middle aged breeders. The results also indicated that storage period of hatching eggs had a significant (P <= 0.05) effect upon all studied traits except fertility and pepped chicks percentages. Fresh hatching eggs had significantly (P <= 0.05) the highest total and fertile eggs hatchability percentages and the lowest early, late and total embryonic mortality percentages followed by those of eggs stored for 7 days, whereas eggs stored for 14 days had the lowest values. From the results reported herein we concluded that breed had a significant effect upon hatchability parameters and Cobb had the best performance followed by Ross whereas Arbor Acres showed the lowest performance. Advancing age of breeders and length of egg storage period had a negative effect upon hatchability parameters. However the reproductive performance of the breeds used in the study performed far less than reported in theirs> companies guide lines.