Interaction between ascites susceptibility and CO during the second half of incubation of two broiler lines. Effect on embryonic development and hatching process

Abstract

1. Because CO₂ during the second half of incubation is known to influence air cell and blood gases, and embryo development, it is postulated that post-hatch development and ascites sensitivity could also be influenced.

2. An ascites susceptible (A) and an ascites resistant (E) broiler line were incubated under standard incubation or high CO₂ conditions (up to 4%) from embryonic day (ED) 10 onwards. The embryonic development and the hatching process of these two lines were compared when incubated under standard or high CO₂ conditions from over the second half of incubation.

3. The A line, selected for high post-hatch growth rate, exhibited a higher relative embryo weight from ED10 until ED16, which was supported by a higher air cell pCO₂, lower air cell pO₂, higher corticosterone and thyroid hormones and earlier hatching time.

4. Incubation under high CO₂ increased air cell pCO₂, retarded yolk consumption, and decreased glycogen concentration in the liver at hatch. Hatchability decreased in both lines when incubated under high CO₂, due to an increased late mortality of embryos that died before IP.

5. These results suggest that the development and metabolism of CO₂-incubated embryos differ from control incubated embryos.

Acknowledgements

N. Everaert was supported by the Fund for Scientific Research Flanders (FWO-Vlaanderen, Brussels, Belgium, grant no. G.0286.04). H. Willemsen and A. Witters were funded by a PhD grant from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen, Brussels, Belgium). V. Bruggeman received a post-doctoral grant from the Fund for Scientific Research Flanders (FWO-Vlaanderen, Brussels, Belgium). We would like to thank Hendrix Genetics for the eggs of the different ascites lines.