Effects of month, season, flock age and egg size (weight) on hatchability and embryonic mortality during incubation period

Decreased hatchability and increased embryonic mortality in hatchery are economically important. The purpose of this study was to investigate the effects of month, season, flock age and egg size (weight) on hatchability and embryonic mortality during incubation period. The data were collected by frequent reference to the hatchery, and the total of hatched eggs from broiler breeder flocks was recorded between March 2016 to September 2016. Moreover, unhatched eggs were thoroughly investigated. In this survey, the third method (unhatched eggs breakout in the end of incubation) was used for different stages of embryonic mortality. Of the total number of 2372604 hatched eggs, 75.73% eggs and 24.27% eggs were hatched and unhatched (embryonic mortality), respectively. The effect of months and seasons spring or summer was significant (p<0.05) on the average percentage of hatchability and embryonic mortality, so that September and summer had the lowest hatch and the highest embryonic mortality. Decreased hatchability and increased embryonic mortality were observed with increasing of the flock age and the egg size (p<0.05). The highest rate of embryonic mortality was in infertility and stage VI. The results of this study showed that month, season, flock age and egg size (weight) have an effect on hatchability and embryonic mortality.