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Fumigation (1): how formaldehyde can affect hatchability

Fumigation with formaldehyde is a widespread and highly effective tool in the battle against contamination by viruses, bacteria and mould in hatcheries. However, it is not entirely without risk for the developing embryo, and a number of conditions (timing, ventilation, humidity, and temperature) need to be met in order to avoid that the gas adversely affects your hatchability. In a series of articles, we will explain why formaldehyde may reduce hatchability, look at methods of improving all aspects of the practice of fumigation and investigate alternative solutions.

By Roger Banwell, Hatchery Development Manager

Numerous studies (Cadirci, 1997; Nwagu, 1997; Yildirim et al, 2003) have indicated evidence of embryonic mortality during incubation due to exposure to formaldehyde during storage. Modern, more productive incubation methods can increase the negative effect of formaldehyde, which makes fumigation practices and management far more critical than is often appreciated.

In modern incubation practices, the levels of ventilation during the early stage of incubation are vastly reduced. This significantly improves hatchability, chick quality, uniformity and post-hatch performance. However, this also causes some of the formaldehyde to remain on the egg shell and enter into the egg, which may adversely affect hatchability.

The blastoderm – the layer of cells from which the embryo develops - is positioned on the upper surface of the yolk which is held in a central position by a combination of the chalazae and the viscous nature of the albumen. The diffusion of CO2 through the porous shell allows the pH of the albumen to rise. As the pH increases, the interaction between two of the albumen proteins (lysozyme and ovumucin) breaks down, leading to a decrease in the albumen viscosity. This allows the yolk and the blastoderm to float towards the shell and towards any potentially harmful concentrations of formaldehyde.

This risk is further heightened when incubating at a high altitude, as shown by Visschedijk (1991). The study clearly showed that the conductance of the egg shell is inversely proportional to the air pressure. This means that at high altitudes where air pressure is low, fewer molecular collisions occur, which eases the passage of harmful formaldehyde through the egg shell (see Fig. 1).

Fig. 1 Egg shell conductance at sea level (left) and at altitude (right) (Visschedijk, 1991)

There are numerous other factors that have a major role to play in this, such as absolute temperature and temperature fluctuations, humidity, shell quality, etc. This makes the practice of fumigation a critical factor in the ability of the hatchery to achieve optimal performance.

In a series of articles covering this topic, we will guide you through all aspects of fumigation and offer useful advice and tips to enable maximum performance.


  1. Cadirci S, Disinfection of hatching eggs by formaldehyde fumigation – a review. Archiv für ÜR Geflügelkunde, 2009, 73, 116-123
  2. Nwagu BI, Factors affecting fertility and hatchability of guinea fowl eggs in Nigeria. World's Poult. Sci. J., 1997, 7, 53, 279-286.
  3. Visschedijk AHJ, Incubation of eggs at high altitude. Avian incubation, Poultry Science symposium series, 1991, 22, 285-291
  4. Yildirim I, Özsan M, Yetisir R, The use of oregano (origanum vulgare L) essential oil as alternative hatching egg disinfectant versus formaldehyde fumigation in quails (coturnix coturnix japonica) eggs. Revue Méd. Vét., 2003, 154, 5, 367-370.