Carbon dioxide during hatching appears to have only a transient effect on chick quality and eggshell temperature (EST) at this time has more important effects on chick physiology, according C.M. Maatjens of HatchTech and co-authors there and at Wageningen University.

These are their main conclusions after two studies investigating the effects of eggshell temperature and carbon dioxide during hatching published in this month's Poultry Science.

In both experiments, three batches of eggs were incubated at an EST of 37.8°C until day of incubation (E) 19. From E19, embryos were incubated at low (36.7°C), normal (37.8°C), or high (38.9°C) EST and at low (0.2 per cent) or high (1.0 per cent) carbon dioxide concentration.

Effects on Chick Quality and Organ Development

In the first experiment, the researchers measured organ growth and embryo and chick quality on E19, internal pipping (IP), hatch and 12 hours after hatch.

A few interactions between EST and carbon dioxide were found at IP, hatch, and 12 hours after hatch but all of these interactions were temporary and in most cases weak.

High EST resulted in a lower relative heart weight compared with low (Δ=0.05) and normal EST (Δ=0.06) at IP, compared with low (Δ=0.11) and normal EST (Δ=0.08) at hatch, and compared with low (Δ=0.11) and normal EST (Δ=0.08) at 12 hours after hatch.

At hatch, high EST resulted in a lower yolk-free body mass (YFBM) than low EST (Δ=0.65).

At 12 hours after hatch, high EST resulted in a lower relative liver weight than low EST (Δ=0.12). At low EST, relative intestinal weight was greater than normal (Δ=0.41) and high EST (Δ=0.37).

The effect of carbon dioxide solely was found at 12 hours after hatch, when a higher relative heart weight (Δ=0.05) and a higher relative lung weight (Δ=0.0542) were found at high carbon dioxide than low carbon dioxide.

High EST during only the hatching phase negatively affected chick development, mainly expressed by the lower relative heart weight at IP, hatch and 12 hours after hatch and lower YFBM at hatch.

The resolving effect of carbon dioxide demonstrates that carbon dioxide only seem to have a temporary effect during the hatching phase, Maatjens and co-authors concluded.

Effects on Chicken Embryo Physiology

Using the same conditions as before, the researchers investigated the effects of EST and carbon dioxide concentration during only the hatching phase on physiological characteristics of embryos and chicks.

For E19, IP, hatch and 12 hours after hatch, blood parameters were analysed and hepatic glycogen was determined.

At IP, hatch and 12 hours after hatch, interactions were found between EST and carbon dioxide, but all these interactions were temporary and, in most cases, weak.

High EST resulted in a lower hepatic glycogen concentration than low (Δ=21.1) and normal EST (Δ=14.43) at IP, and a lower hepatic glycogen concentration than with low EST (Δ=6.24) at hatch.

At hatch, high EST resulted in lower haematocrit value (Δ=2.4) and higher potassium (Δ=0.5) than low EST.

At 12 hours after hatch, high EST resulted in a higher lactate concentration than low (Δ=0.77) and normal EST (Δ=0.65). High EST resulted in higher potassium than low (Δ=0.4) and normal EST (Δ=0.3).

An effect of carbon dioxide solely was only found at IP, when high carbon dioxide resulted in a lower pH (Δ=0.03) and a lower hepatic glycogen concentration (Δ=7.27)than at low carbon dioxide.

High EST during only the hatching phase affected embryo and chick physiology, indicated by the lower hepatic glycogen levels at IP and hatch.

High carbon dioxide affected pH and hepatic glycogen at IP, concluded the researchers. They added that the effects of carbon dioxide were only found at low EST, which emphasises the large effect of EST during the hatching phase.

References

Maatjens C.M., I.A.M. Reijrink, R. Molenaar, C.W. van der Pol, B. Kemp and H. van den Brand. 2014. Temperature and CO2 during the hatching phase. I. Effects on chick quality and organ development. Poultry Science. 93(3):645-654. doi: 10.3382/ps.2013-03490

Maatjens C.M., I.A.M. Reijrink, I. van den Anker, R. Molenaar, C.W. van der Pol, B. Kemp and H. van den Brand. 2014. Temperature and CO2 during the hatching phase. II. Effects on chicken embryo physiology. Poultry Science. 93(3):655-663. doi: 10.3382/ps.2013-03491

A fee may be payable to access the full papers using the links above.

March 2014