Automated egg flat washers

The plastic egg flats used on many poultry operations are fully washable and disinfectable. The most effective method of cleaning and disinfection is through the proper use of automated flat washers. With these washers, the flats can be cleaned with hot water and disinfected with chemical disinfectants that are compatable with hot water sanitation (see How much can they take? for a guide to disinfectants).

Flats emerging from automated flat washers should be visibly free of organic material. It is important that egg flats are not stuck together and allow the wash water to come in contact with all surfaces. Care must be taken to prevent the accumulation of organic material in the flat washer since that will inactivate most disinfectants.

Automated egg flat washer

Heating of egg flats for disinfection

It may also be possible to heat egg flats in order to kill specific disease agents (see How much can they take? for a guide to heat inactivation of various disease agents).

Some agents are very sensitive to heat and can easily be inactivated by heating even at a relatively low temperature. However, there are some critical points to remember.

Heating (or any form of disinfection) can only work if it is applied to every egg flat. Therefore, it is critically important that temperatures be measured at the center of the room that is being heated, in the middle of a stack of flats as shown below.

Proper place (red star) to measure the temperature used to heat egg flats for the purpose of disinfection

It is not only important to know how high the temperature gets on the surface of the egg flats, it is also important to know how long they are exposed to that temperature.So, there are two critical parameters to measure, temperature and time of exposure and the question is how to do that.

There are lots of thermometers and remote thermosensing devices commercially available (see "Temperature Loggers" also available as an Excel file for a listing). Some of them are cost effective but may be difficult to use, others may require a computer to download temperature data and others are very expensive but may work very well. Which ones will work in the systems designed for use on poultry farms depends on the availability of personnel to monitor the process and ready access to the flats at the center of the pile.

In order to heat egg flats in the center of a room to a specific temperature, it will require heating from a furnace or other heat source that may reach very high temperatures and could melt the flats placed closest to it. In experiments done at the University of California, Davis, egg flats were heated to various temperatures in order to determine their approximate melting temperatures. The results of those experiments are shown below.

Treatment	212F (100C) for 1 hour	250F (121C) for 25 min
Description	The flats were soft when they were removed, but were neither distorted in shape nor melted together.	The flats were distorted and melted together after treatment.
Photograph after treatment

It is not only critical to heat flats to a specific temperature for a certain amount of time to inactivate a disease agent, it is also important that the heating process also dry out any liquid or organic material left on the flats.

Experiments were done at the University of California, Davis, in order to determine the rate of drying of egg flats at 140F (60C). After 1 hour, a small amount of egg on the egg flat was completely dried, but heating overnight (12-14 hours) was required to dry larger volumes of liquid egg from the flats. The results of the experiments are shown below.

Amount of liquid	1/16 teaspoon	1/8 teaspoon	1/4 teaspoon
Hours required for drying	1 hour at 140F (60C)	3 hours at 140F (60C)	12-14 hours at 140F (60C)