Effects of interaction of incubator CO₂ levels and mixing hatching eggs of different embryo growth trajectory on embryo physiological and hatching parameters

Abstract

1. Two experiments were designed to investigate the effects of mixing eggs of different genotype and incubating with different CO₂ concentrations on embryonic parameters. Half of the eggs were incubated in a CO₂ controlled incubator (VCO₂) during the first 10 d of incubation and the other half was incubated at standard incubation ventilation rate (SV).

2. From 10 to 18 d of incubation, thick albumen and embryos were weighed. Blood samples were collected at d 18 of incubation, at internal pipping and at hatch for determination of triiodothyronine (T₃), thyroxine (T₄) and corticosterone concentration. During the last 2 d of incubation, hatching events of individual eggs were monitored every 2 h.

3. From 4 to 5 d of incubation in the SV group of Experiment 1, pH values of Ross strain chickens were lower than those of Isa Brown. From d 12 of incubation onwards, Ross embryos grew faster than those of Isa Brown. At 14 and 16 d of incubation, Ross eggs in the CO₂ controlled incubator had lower albumen weights compared to all other treatments.

4. T₃ concentrations in Ross embryos were higher than those of Isa Brown embryos. Chicken weight at hatch was in the following order: Isa Brown SV < Isa Brown VCO₂ = Ross SV < Ross VCO₂.

5. In Experiment 2, incubation time of VCO₂ eggs until internal pipping, external pipping and hatch was significantly shorter than that of SV eggs.

6. It was concluded that mixing of hatching eggs of differential embryo developmental trajectory affects their hatching process.

ACKNOWLEDGEMENT

The first author was supported by the Flemish Interuniversity Council (VLIR) (ZEIN 2006 PR 32).