Temperature and relative humidity (RH) are very important factors affecting embryo development, hatchability and post-hatch performance, according to Rute Noiva and colleagues at the University of Lisbon in Portugal.

Their study, publishing in BMC Veterinary Research recently, aimed at characterising embryonic metabolic and behavioural response to a harsh incubation environment generated by manipulations (elevations and drops) in these two key factors.

The researchers also attempted to establish patterns of metabolic and behavioural response, as well as mortality and the development of malformations, all of which can potentially be used in monitoring incubating operations and diagnosing problems with faulty equipment.

Of all the parameters monitored throughout embryonic development, the ones shown to be most affected were: albumen-weight to egg-weight ratio (AR); yolk-weight to egg-weight ratio (YR); embryo-weight to egg-weight ratio (ER); heart rate (HR); voluntary movements per minute (VMM); mortality rates; malformation prevalence and type.

The most significant changes in the evolution of AR and YR throughout incubation involved delay and reduction in the amplitude of the expected drop in albumen and yolk levels, reflecting lower nutrient consumption by the embryo.

ER tended to grow more slowly and remain lower than the established normal, especially in embryos challenged with temperature treatments. HR and VMM were considered to be strong indicators of embryonic stress, as all treatments applied resulted in elevated heart rate and decreased embryo movement.

Mortality rates for both temperature-related treatments were higher during the first four days of incubation. Changes in relative humidity have produced less radical effects on mortality. Malformation rates were higher for embryos subjected to high incubation temperatures and were most prominently related to the abdominal wall, head, skull and limbs.

Overall, manipulations in environmental (incubator) temperature during incubation produced more drastic changes in embryo development than humidity-related manipulations, especially where mortality and malformation rates were concerned.

The Lisbon-based researchers describe changes in embryonic metabolism and behaviour, mortality and malformation rates in response to changes in environmental temperature and relative humidity. The patterns they revealed may help to diagnose equipment malfunctions relating to temperature or relative humidity.

Reference

Noiva R.M., A.C. Menezes and M.C. Peleteiro. 2014. Influence of temperature and humidity manipulation on chicken embryonic development. BMC Veterinary Research. 10:234. doi:10.1186/s12917-014-0234-3

October 2014