**2. A brief overview from lay to artificial incubation of hatching eggs**

In commercial broiler breeder facilities, eggs are removed from the hen and transported to a commercial hatchery for artificial incubation. Hens lay their eggs in clean (or dirty) nest boxes or may lay their eggs in a contaminated environment, such as the floor. Factors including facility design and the lighting program can affect the onset and location of lay. Since floor eggs have been shown to harbor more microbiological contamination than nest eggs [14], care should be taken to avoid disrupting the hen's laying process.

The egg collection procedure, and egg handling and storage, have been reviewed [15]. Conveyor belts or mechanical apparatuses transport the eggs post-lay to a common area for collection in modern breeder facilities. Prompt collection of eggs is ideal to avoid an increased risk of damage, contamination, and reduced hatchability [16]. The egg temperature declines post-lay and should not increase until the time of preheating before placement in the incubator. Fertile eggs are regularly stored in coolers (15–20C) to optimize survival until artificial incubation. Demand for broiler chicks will dictate how quickly the incubation process will begin for fresh or stored fertile eggs. Single-stage and multi-stage incubators have been used in commercial broiler hatcheries, although multi-stage incubators tend to be the most common. During multi-stage incubation, different embryonic stages are co-incubated to equilibrate the temperature. The multi-stage incubators can be more economically feasible, but regular sanitation is difficult. Single-stage incubators are becoming more popular.

*Value and Limitations of Formaldehyde for Hatch Cabinet Applications: The Search… DOI: http://dx.doi.org/10.5772/intechopen.104826*

Although temperature management can be more tedious for multi-stage incubators, the single-stage incubators can be sanitized after each 18-day embryonic cycle. At DOE18, embryonated eggs are transferred to hatch cabinets. Disinfectants are applied during the hatching phase to reduce the microbial load in the hatch cabinet. Hatchery sanitation practices, and the impact of hatchery contamination, will be discussed below.
