Effects of different hatcher temperatures on hatching traits of broiler embryos during the last five days of incubation

This study deals with the effects of different hatcher temperatures on hatching traits in modern commercial broiler eggs during the last five days of incubation. The hatching eggs were obtained from a 52wk old (Ross 308) flock. All eggs were distributed randomly into one incubator and incubated for 17 d using uniform conditions (37.6 ± 0.5 °C and 58% relative humidity). At the start of 18 days of incubation, the eggs were randomly distributed to four experimental hatching cabinets. The temperatures were set in the cabinets at 36.1, 37.2, 38.3 and 39.4 °C from 17 d of incubation until hatch. Hatching time, hatchability, age of mortality and the incidence of embryo malpositions were recorded as percentage of fertile eggs. The highest mean embryonic heat production or eggshell surface temperature occurred in the hatching cabinets operated at 39.9 °C and lowest at 36.1 °C. Eggs incubated at 37.2 °C and 38.3 °C had a significantly higher hatchability than the other treatment groups. High embryo mortality at the late term stage of development was recorded at low (36.1 °C) and very high temperatures (39.9 °C). No significant difference in the incidence of malpositions was observed among the groups. These findings revealed that hatchability might be improved if incubation temperatures of 37.2 °C to 38.3 °C are used during last five days of incubation. The results indicate that the modern hatching broiler egg shows almost similar pattern as past generations for heat production and temperature in hatchers during the last five days of incubation. In other words, in spite of genetic improvements in the modern broilers, the incubation conditions and techniques remained largely unchanged. _______________________________________________________________________________________