Best Practices for Selection and Care of Hatching Eggs: From Collection to Storage

The success of any hatch begins long before the eggs enter an incubator. What happens in the hours and days after an egg is laid – how it is collected, inspected, sanitized, and stored – determines whether a healthy chick will emerge on day 21. Yet these pre-incubation steps are often where producers lose the most hatchability, simply due to oversights that are entirely preventable. Whether you manage a commercial breeder flock or a small poultry operation, mastering the selection and care of hatching eggs is one of the highest-return practices you can adopt.

Hatching eggs vs. table eggs: a critical distinction 🔗

The first thing to understand is that not every egg is a hatching egg. Table eggs – the kind found in grocery stores – are typically unfertilized. They contain no embryo and will never develop into chicks, regardless of how they are stored or incubated. Hatching eggs, on the other hand, must come from flocks where roosters are actively mating with hens. In a well-managed breeding flock, fertility rates typically range from 85% to 95%, influenced by the male-to-female ratio, nutrition, and overall flock health.

Crucially, a hatching egg is not just an inert object – it contains a living embryo that, while in a dormant state during storage, remains sensitive to temperature, humidity, and handling. The embryo already represents approximately 23.5 hours of development inside the hen’s body by the time the egg is laid. This biological reality is what makes proper selection and pre-incubation care so consequential.

Criteria for selecting the right eggs 🔗

Not every egg from a breeding flock qualifies for incubation. Selecting the right eggs upfront directly improves hatchability and reduces contamination risks inside the incubator.

Breeder flock quality 🔗

Eggs should come from breeders that are well-developed, mature, and healthy; compatible with their mates and producing a high percentage of fertile eggs; fed a complete breeder diet; and not closely related to each other. Flock health is non-negotiable – diseases such as infectious bronchitis and Mycoplasma gallisepticum adversely affect egg quality, hatchability, and chick viability. A strict biosecurity plan should be enforced at every step, from the breeder farm to the hatchery.

Egg size and shape 🔗

Egg size matters significantly. Eggs below 45-50 grams have a lower chance of hatching compared to medium and large eggs. Excessively large eggs are more likely to be double-yolked, which rarely develop properly. Very small eggs – often from young pullets – typically lack the nutrients required for complete embryonic development. Abnormally shaped eggs, including those that are very round, overly elongated, or have surface ridges, indicate shell formation problems and should be excluded.

Shell integrity 🔗

Only eggs with intact, clean shells should enter the incubator. Eggs with hairline cracks have low hatchability and poor chick quality – even cracks invisible to the naked eye allow bacteria to penetrate the shell and moisture to escape, both of which lead to embryonic death. Shell integrity checks should be systematic, not casual.

Egg collection: frequency and hygiene 🔗

How and when you collect eggs is just as important as which eggs you select. Eggs should be collected at least three times daily. When daily high temperatures exceed 85°F (29.4°C), collection frequency should increase to five times a day. The reason is straightforward: if nest temperatures exceed 26.7°C (80°F) for extended periods, the embryo may begin premature development. Once this incomplete development is interrupted by cooling, the embryo dies.

Dirty and cracked eggs should be sorted from clean eggs as soon as possible after collection and kept separate. Clean nest eggs must be collected first, before handling any dirty or floor eggs, to prevent cross-contamination. Floor eggs and heavily soiled nest eggs will hatch less well than clean nest eggs and may spread contamination throughout the hatchery – they should never be placed back into nests.

Important: Do not wash dirty eggs with water or wipe them with a damp cloth. Washing removes the egg’s protective cuticle and exposes it to disease organisms; the rubbing action can also force bacteria through the pores of the shell. Visibly dirty eggs should simply be rejected from the hatching batch.

Candling: seeing inside the egg 🔗

Candling is one of the most reliable tools available for assessing egg quality before and during incubation. Egg candling involves shining a bright light through the egg shell to see inside it – the term originates from the historical practice of holding an egg up to a candle flame. Today, specialized candling lights or even strong flashlights are used.

Before incubation, candling helps identify hairline cracks that are invisible to the naked eye, as well as eggs with abnormal internal contents. Cracks in the shell that would otherwise go undetected are easily identified through candling; no eggs with cracked shells should be set, as they are not only unlikely to hatch but risk converting into exploding “bangers” that contaminate the entire incubator. During incubation, blood vessels in chicken eggs are normally observable within 7 to 10 days, and by day 18 the embryo takes up most of the egg and appears as a dark area. If an egg appears clear during candling – showing no blood vessels or dark structures – it is either infertile or the embryo has died early.

Candling is also used to check the size and position of the air cell, which gives information about moisture loss during storage and incubation. The most common causes of early embryonic death include rough handling, incorrect storage temperature, adverse genetic traits, and breeder flock aging – many of which can be flagged during candling.

Fumigation and disinfection 🔗

Hatching eggs carry bacteria on and within their shells that can cause serious losses inside an incubator. Disinfection is therefore not optional – it is a standard biosecurity requirement. Eggs should be disinfected as soon as they are collected, while still warm, ideally within two hours of being laid, using only products labeled specifically for hatching egg application.

Fumigation using formaldehyde gas has historically been the most widely used method. However, this approach is no longer recommended because it is harmful to the embryo, increasing early embryonic death, and is hazardous to human health. Modern alternatives based on glutaraldehyde, quaternary ammonium compounds, stabilized hydrogen peroxide, and peracetic acid are now available and equally effective. Dry methods such as UV light or ozone are preferable over wet methods since they avoid any risk of solution being drawn through the shell pores.

When fumigation is used, specific conditions must be met for it to be effective. The room must be well sealed, a circulating fan should be run to distribute the fumigant between eggs, and the gas should be allowed to circulate for at least 20 minutes. Critically, fumigation must never be performed during the first 24 to 96 hours of active incubation, as it will kill the developing embryo at this sensitive stage. Equipment that comes into contact with hatching eggs – setter trays, suction heads of egg lifters – must also be regularly cleaned and disinfected.

Storage conditions: temperature and humidity 🔗

Once collected and sanitized, hatching eggs must be stored under tightly controlled conditions to preserve embryo viability until incubation begins. Temperature and humidity are the two most critical variables, and getting them wrong even slightly can have significant consequences.

Temperature 🔗

The recommended storage temperature for hatching eggs is 12.8°C to 18.3°C (55°F to 65°F). If fertile eggs reach temperatures above 72°F (22.2°C), embryos will begin to develop abnormally, weaken, and die. Embryos stored below 46°F (7.8°C) also experience high mortality. Room temperature is generally too warm, and a standard refrigerator is typically too cold. A dedicated egg storage room with refrigeration is the most reliable solution. For storage beyond one week, the temperature should be reduced to around 12°C; eggs should never be exposed to direct sunlight at any time during storage.

Research has shown that fertile eggs held under recommended conditions completely failed to hatch when stored for more than 25 days, and even after 7 days of storage, a significant reduction in hatchability was noted. To maximize hatch rates, eggs should ideally be set within 3 to 7 days of production.

Humidity 🔗

Fertile eggs should be stored at 70 to 80 percent relative humidity. Insufficient humidity causes excessive moisture loss from the egg, which depletes the nutrients and fluid the embryo needs for development. If eggs are stored for up to 10 days, 50-60% relative humidity is sufficient; for longer storage periods, a higher humidity of 70-80% helps prevent excessive moisture loss. Humidity above 80% should be avoided, as it promotes fungal growth on the shell surface.

One important precaution is to prevent condensation – commonly called “egg sweating.” Condensation on the eggshell impairs the egg’s natural defense mechanisms and creates an ideal environment for bacterial growth, allowing microorganisms to penetrate the shell. This happens when cold-stored eggs are moved into a warmer, more humid environment too rapidly. Eggs should always be warmed gradually before setting.

Egg positioning and turning during storage 🔗

How eggs are oriented and handled during storage also affects hatchability. When storing eggs for less than 10 days, they should be stored with the large end up. This keeps the air cell properly positioned and prevents the yolk from migrating and adhering to the shell membrane – a condition that can damage the embryo.

For eggs stored beyond a week, regular turning is essential. Eggs should be turned (by twisting) several times a day during storage, with the pointed end facing downward. Turning prevents the yolk from sticking to one side of the shell interior, which would physically damage the developing embryo once incubation begins. The number of embryonic cells in an egg can remain stable for seven days in proper storage; after seven days, the embryonic cell count begins to decrease, leaving the eggs at greater risk of not hatching. For eggs stored beyond 14 days, a technique called SPIDES (Short Period Incubation During Egg Storage) – where eggs are briefly warmed to incubation temperatures for short periods – has been shown to help preserve embryo viability.

Key summary: pre-incubation checklist 🔗

Managing hatching eggs effectively comes down to discipline at each step. Here is a practical summary of the non-negotiables:

• Fertility first: Only eggs from well-managed breeder flocks with confirmed high fertility rates qualify for hatching.
• Collect frequently: Collect at least 3 times daily, and up to 5 times daily in hot weather, to prevent premature embryo development.
• Reject promptly: Exclude dirty, cracked, misshapen, oversized, or undersized eggs immediately. Never wash dirty eggs.
• Candle before setting: Use a candler to detect hairline cracks and assess internal quality before incubation begins.
• Disinfect early: Sanitize eggs within 2 hours of collection using approved products; avoid formaldehyde where possible.
• Store correctly: Maintain 12.8-18.3°C and 70-80% relative humidity; store large end up; avoid condensation and direct sunlight.
• Turn regularly: Turn stored eggs multiple times daily if holding beyond 7 days to prevent yolk adhesion.
• Set promptly: Aim to incubate within 3-7 days of collection for best hatchability.

What do you think? Given that hatchability can drop significantly after just 7 days of storage, how do small-scale poultry producers balance the need to accumulate enough eggs before setting with the pressure to minimize storage time? And if you were advising a new breeder flock manager, which single pre-incubation practice do you think would have the greatest impact on improving hatch rates in their first season?

References

1. https://www.purinamills.com/chicken-feed/education/detail/hatching-eggs-at-home-a-21-day-guide-for-baby-chicks
2. https://www.emtech-systems.com/technical-talk/maximizing-hatchability-the-critical-role-of-premium-hatching-eggs/
3. https://hn-int.com/hatching-egg-handling/
4. https://www.thepoultrysite.com/articles/care-and-incubation-of-hatching-eggs
5. https://ask.ifas.ufl.edu/publication/VM094
6. https://layinghens.hendrix-genetics.com/en/news/considerations-better-hatchability/
7. https://hn-int.com/hatching-egg-management-2/
8. https://layinghens.hendrix-genetics.com/en/articles/hatching-egg-quality/
9. https://www.thepoultrysite.com/articles/investigating-hatchery-practice-appendices
10. https://poultrykeeper.com/incubation-brooding/candling-eggs/
11. https://www.nadis.org.uk/disease-a-z/game-birds/diseases-of-game-birds/part-2-the-hatchery/
12. https://cdn-de.agrilife.org/extension/departments/posc/posc-pu-018/publications/files/incubating-and-hatching-eggs.pdf
13. https://agritech.tnau.ac.in/expert_system/poultry/Incubation%20and%20Hatching.html
14. https://www.raising-happy-chickens.com/choosing-hatching-eggs.html
15. https://www.deerrunfarmmd.com/blogs/the-egg-ucated-chicken/increase-hatchability-using-better-hatching-egg-care-and-storage-practices