Washing Hatching Eggs

To wash your eggs or not to wash your eggs is the biggest, most controversial questions in the backyard chicken industry today. While it’s perfectly ok to not wash eggs for consumption until you’re ready to use them, it may actually prove to be more beneficial to your hatch success rate to wash your eggs for hatching.

One of the last steps for a hen to lay an egg is for her to apply the cuticle, or the bloom, to the egg. The cuticle is the natural defense coating on the egg that fills it’s pores and protects it from bacteria entering the shell. It may seem counter-active in protecting the goal of having the best possible hatch rate by washing the cuticle off the egg, but understanding the moments just after the hen lays the egg is the key to understanding the necessity of washing hatching eggs.

The egg is especially vulnerable to microbial contamination immediately after it has been laid. Although the hen applies the cuticle to the egg before it is laid, it doesn’t fully form until the egg has cooled down and the cuticle has dried. The time is takes for the egg to cool down and the cuticle to dry depends on the location and condition of the egg laying site. What’s clean should never meet what’s dirty. Egg contents are usually sterile at the time of lay. A dirty nest box or laying site can quickly alter the clean-state of a freshly laid egg. Since both eggs and feces exit through the avian cloaca, nest boxes and other laying sites aren’t usually the cleanest place for hatching eggs to be laid. This sort of environment and unfortunate natural process of the laying cycle provides opportunities for bacterial contamination. Pathogens found to be in feces can penetrate egg pores in less than 30 minutes after an egg is laid while it’s cooling down. A freshly laid egg has the same temperature of the hen (107^F) when it’s first laid. As the egg cools it’s contents will shrink and begin to pull air and other bacterias on it’s shell through it's pores before the cuticle has had time to dry and become effective.

The best way to limit contamination of the egg immediately after it is laid is to ensure adequate egg collection frequency, clean nest boxes and laying sites often and disinfect the eggs while they’re still warm. Large commercial hatcheries have several ways of disinfecting their hatching eggs, including ozone fumigation and UV lights, but for a backyard breeder the simplest, cheapest and most effective way is to wash the eggs.

A specific washing technique is necessary to ensure the effectiveness of washing the eggs to eliminate contamination. Below is a step by step guide to washing your hatching eggs safely.

1. Collect your eggs often to minimize the amount of debris on your eggs. The higher number of bacteria on the shell, the higher the penetration rate of bacteria into the eggs, contaminating their contents.

2. Wash your eggs in warm water. A temperature of 98-1050F is most ideal to prevent contamination. Warm water allows the contents of the egg to expand helping to push out any previously absorbed bacteria. Avoid using cold water as it would further pull more bacteria into the egg.

3. While the eggs are still wet, but soon to dry, thoroughly spray them with a diluted 10% bleach solution as a sanitizer. Allow them to air dry. The bleach solution, although not strong enough to affect the contents of the egg, will help kill any left over bacteria that was previously absorbed, but not pushed out by the egg during washing.

4. Once the eggs have fully air dried, apply a diluted Tek-trol solution to them and allow to air dry one final time. This solution should be applied as thoroughly as possible. The Tek-trol solution is specifically used on hatchery equipment for disinfection purposes, but can also be applied directly to the hatching eggs to kill any microbial organisms. The Tek-trol solution has been tested and proven to kill both Mycoplasma Gallisepticum and Mycoplasma Synoviae along with several strains of Salmonella bacterias if appropriately diluted and applied. The film created and left on the egg from the use of Tek-trol imitates the same behavior as the natural bloom from the hen.

5. Allow the eggs to full air dry before incubating. This will eliminate the possible creation of an optimal micro climate for bacterial growth in a warm incubation environment.

Further evidence that washing hatching eggs is necessary is that unwashed, soiled eggs have a higher risk of cross contamination in the incubator. High numbers of soiled eggs in the incubator is probably the single biggest cause of poor chick quality and first week mortality. Cross contamination between a heavily soiled egg and one that may be fairly clean can lead to lower fertility rates, early embryonic mortality and a higher percentage of rotten eggs. Removing bacteria and microbial pathogens before they have a chance to multiply and contaminate other eggs during incubation is essential to your incubation process.

Adding a proper washing routine to your incubation process is the best form of bacteria removal prior to incubation. This additional washing step can lead to an increase in your hatch success rate almost immediately and have you feeling less stressed over the possibility of an unbeknownst rotten egg exploding mid-incubation.