Optimal egg storage at the hatchery is critical for successful hatching. When eggs are stored correctly, embryo development is suspended, and this minimizes embryo mortality, maximizes hatchability and helps to ensure chick quality.
Numerous factors can impact egg storage, and hatchery managers need to pay particular attention to the following.
Control arrival conditions
On arrival at the hatchery, eggs should be transferred to a temperature-controlled egg holding room. If initial delivery is to an unventilated area, move the eggs as quickly as possible and never leave them uncontrolled overnight.
If eggs do not receive a period of rest after transport, early embryonic mortality will increase. Wait at least 12 hours after eggs arrive in the hatchery before setting them for incubation.
Minimize egg storage duration
Storage starts at day of lay and includes the days that eggs are kept at the breeder farm and the duration of transport. Add these days to the date of receipt in the hatchery’s egg storage room.
Eggs are usually stored for a number of days before incubation starts. This period can vary considerably from zero to 20 days or even more. However, it should be remembered that long term storage of eggs decreases hatchability and chick quality and creates logistical issues for hatchery employees.
Optimal hatching and chick quality is achieved when eggs are set between three to six days after day of lay. Unfortunately, even in broiler hatcheries, storage times greater than six days are common for reasons including the need to build up egg numbers so that a house can be populated from one breeder flock or adjusting for order size changes caused by market fluctuations. Downsides to storing eggs for longer periods include:
- Greater early embryonic mortality due to cell death
- Decreased hatchability by approximately 0.7% - 1.0% per day for every day after six days
- An extra hour of incubation time for every storage day in excess of six days
Control storage temperature
Proper temperature reduction can slow embryo development until it stops. This is called threshold temperature or physiological zero for development and is the desired temperature for egg storage rooms.
Subthreshold temperatures may result in disproportionate development that interferes with embryonic viability.
Differences in temperature will result in the eggs reaching incubation temperature at different times and, therefore, hatching at different times, increasing the hatch window.
Although research recommends that egg storage temperature be adjusted depending on the egg age, this practice is considered too complicated and is rarely followed. Instead, most hatcheries use a constant 17-18°C.
Egg storage temperature should be adjusted down to be optimal for the oldest eggs. Fresh eggs hatch just as well when stored at colder temperatures, but older eggs suffer badly when stored at warmer temperatures. For longer storage times, consider 15°C.
In addition to slowing embryo deterioration, lower temperatures slow the physical deterioration of the albumen and yolk membranes, which are needed to support optimal hatchability.
When storing eggs for long periods, make sure that the temperature is brought down as soon as possible – do not wait for seven days before reducing the temperature.
Control storage humidity
During storage, moisture is lost through the eggshell into the atmosphere. A relative humidity target of 75-80% is recommended to prevent eggs from losing too much moisture. The humidity should be a fine mist that does not result in any of the eggs getting wet.
Humidifiers need routine maintenance and cleaning. Left unchecked, they are natural reservoirs for bacteria.
Monitor egg storage room conditions
For optimal egg storage, conditions must remain uniform and constant. Record climate conditions daily and consider using "minimum-maximum" thermometers. Read them every day to record the extreme readings every 24 hours.
Monitor at multiple locations throughout the storage room. Use a calibrated device to routinely check proper functioning of equipment. Ensure sensors are not in the direct line of temperature or humidity sources as this will lead to false readings. Similarly, do not place sensors against walls.
Control physical parameters within storage areas
Other factors to consider include:
Do not clean the room and equipment when hatching eggs are present.
- Position eggs a sufficient distance from walls, heaters and humidifiers to maximize air circulation and to ensure uniform conditions.
- Avoid direct air flow onto eggs from fans, room coolers and/or humidifiers. Direct air flow on eggs can increase moisture loss and cause temperature variation throughout the room.
- Use air movement (via ceiling fans) to create an even environment. Set fans to draw air rather than to push it.
- If eggs need to be stored for more than 10 days, store them small end up, starting on the first day of storage. If this is not possible because eggs are stored on setter trays, turn the eggs an uneven number of times per day.
- Avoid egg ‘sweating’ (moisture condensation on eggs) since it provides an ideal environment for the growth of microorganisms that may penetrate the eggshell.
Consider pre-storage incubation
Pre-storage incubation is a new approach that involves incubating eggs for short periods during the storage period. The process aims to develop the embryo to a stage of embryonic development that is better able to survive storage.