Effects of Incubator Carbon Dioxide and Oxygen Levels, and Egg Weight on Broilers' Hatchability of Fertile Eggs

This study investigated the effects of incubator carbon dioxide (CO2) and oxygen (O-2) levels, and egg weight (EW) on embryo mortality (EM) and hatchability of fertile eggs (HFE). A total of 1920 hatching eggs were obtained from a middle-aged (41 weeks) ROSS 308 broiler breeder flock. The eggs were classified according to EW as heavy (69.63 +/- 0.09 g), medium (65.20 +/- 0.04 g) and light (61.11 +/- 0.08 g) and randomly allocated to four separate identical incubators. To these incubators, four different incubator ventilation programmes (IVP) classified as control (C; 0.7% CO2 and 20.9% O-2), high CO2 (HC; 1.1% CO2 and 20.3% O-2), high O-2 (HO; 0.6% CO2 and 22.0% O-2), and high CO2 + O-2 (HCO; 0.9% CO2 21.0% O-2) were applied, and EM and HFE were examined. IVP affected EM and HFE; a higher rate of early EM and a lower rate of HFE were obtained from the HO group compared to the HCO group, and a lower rate of HFE was observed in the HO group than to the C group (p<0.05). An association was found between EW and IVP (p<0.05), being more evident in early EM for light eggs. Consequently, IVP; i.e., different CO2 and O-2 levels in the incubator affected the hatching results. This is considered to be due to the altitude of the experiment (724m) and the uniform eggs being obtained from the same middle-aged flock, and incubator O-2 levels should be taken into consideration, as well as CO2.