The effects of heating of eggs during storage, broiler breeder age and length of egg storage on the hatchability of fertile eggs were examined in a study by M. Gucbilmez from the University of Ankara in Turkey and co-authors there and Professor John Brake of North Carolina State University in the US.

Their study, published in Poultry Science was entitled Effects of pre-incubation heating of broiler hatching eggs during storage, flock age, and length of storage period on hatchability.

Eggs were collected from Ross 344 male × Ross 308 broiler breeders on paper flats, held overnight (for one day) at 18°C and 75 per cent relative humidity, and then transferred to plastic trays.

In experiment 1, eggs were obtained at 28, 38 and 53 weeks of flock age. During a further 10 days of storage, eggs either remained in the storage room (control) or were subjected to a heat treatment regimen of 26°C for two hours, 37.8°C for three hours or 26°C for two hours in a setter at day 5 of storage.

In experiment 2, eggs from a flock at 28 weeks of age were heated for one day of a six-day storage period.

Eggs from a 29-week-old flock were either heated at day 1 or 5 of an 11-day storage period in experiment 3.

In experiment 4, 27-week-old flock eggs were heated twice on days 1 and 5 of an 11-day storage period.

Control eggs stored for six or 11 days were co-incubated as appropriate in each experiment.

Heating eggs at day 5 of an 11-day storage period increased hatchability in experiment 1.

Although no benefit of heating 28-week-old flock eggs during six days of storage in experiment 2 was observed, heating eggs from a 29-week-old flock on day 1 or 5 of an 11-day storage period increased hatchability in experiment 3.

Further, heating eggs from a 27-week-old flock twice during 11 days of storage increased hatchability in experiment 4.

The researchers suggested that these effects were probably due to the fact that eggs from younger flocks have been reported to have many embryos at a stage of development where the hypoblast had not yet fully developed - less than EG-K12 to EG-K13 - such that heating during extended storage advanced these embryos to a more resistant stage.

Reference

Gucbilmez M., S. Özlü, R. Shiranjang, O. Elibol and J. Brake. 2013. Effects of preincubation heating of broiler hatching eggs during storage, flock age, and length of storage period on hatchability. Poult. Sci. 92(12):3310-3313. doi: 10.3382/ps.2013-03133