The effects of temperature fluctuation during 7 d of storage on hatchability and embryonic mortality of broiler hatching eggs was examined with eggs obtained from commercial flocks of Ross 344 male X Ross 308 female broiler breeders at 53 wk and 50 wk of age in Experiments 1 and 2, respectively. The eggs were laid in mechanical nests when the seasons were autumn and winter in Experiments 1 and 2, respectively.
In each experiment, a total of 1,200 eggs that had been laid within a 1 h period were collected in the afternoon and then transferred by vehicle with air condition to an experimental egg storage facility within 2 h. The eggs were then randomly assigned to two chambers with either a constant temperature of 18°C or a temperature that fluctuated daily between 18°C and 21°C four times (0900, 1200, 1500, and 1800) in Experiment 1 or three times (0900, 1300, and 1700) in Experiment 2. This latter treatment was intended to mimic the typical situation where an egg storage room door was opened to move freshly collected eggs into the storage room. The temperature increase periods were approximately 45 and 30 min in Experiments 1 and 2, respectively.
The relative humidity in the chambers averaged 59 or 70% in Experiments 1 and 2, respectively. Each tray of 60 eggs was considered to be a replicate and there were 10 replicate trays per egg storage temperature treatment. The eggs were randomly set in two laboratory single stage incubators. At the time of removing the chicks from the hatchers, all unhatched eggs were opened and examined macroscopically to determine fertility or embryonic mortality (early dead (0 to 7 d), middle + late dead (8 to 21 d plus pipped eggs), and to calculate percentage hatchability of fertile eggs. There was a significant increase in early embryonic mortality due to fluctuating storage temperature in both experiments. There was a significant increase in hatchability of fertile eggs in Experiment 2, with a similar trend in Experiment 1, as a result. These data showed that early embryonic development in eggs from flocks over 50 wk of age could be adversely affected by a 3 or 4 times daily increase in storage temperature of only 3 C.
Key Words: egg storage temperature, hatching egg storage, hatchability, broiler breeders, early embryonic mortality.