📌 The Hidden Science Behind Egg Turning and Hatching
Every poultry farmer knows that turning eggs during incubation is vital. Without turning, embryos can stick to the shell membrane, leading to weak development and high mortality rates. But what many don’t fully realize is that turning eggs must be stopped at a precise stage before hatching. Failing to do so is one of the most common mistakes in incubation management, often costing farmers entire batches of chicks.
This blog explains in detail why stopping egg turning before hatching is crucial, the science behind embryo positioning, the risks of continued turning, and practical tips for timing and management. Whether you’re hatching chicken eggs, quail, ducks, or turkeys, understanding this principle can make the difference between a poor hatch rate and a successful one.
🐣 Understanding Egg Turning During Incubation
Egg turning is one of the most important processes during the incubation period. In nature, a broody hen turns her eggs several times a day, ensuring proper embryo development. In artificial incubation, farmers replicate this process using automatic or manual turners.
The key functions of egg turning are:
- Preventing the embryo from sticking to the inner shell membrane.
- Promoting even heat distribution inside the egg.
- Supporting proper development of the circulatory system and organs.
- Encouraging strong skeletal and muscular growth in the embryo.
Without turning, embryos often develop abnormally, leading to crooked legs, unabsorbed yolks, or even death inside the shell. However, while turning is necessary in the first stages, continuing it too close to hatch time can disrupt the natural hatching process.
⏳ The Critical Window – When to Stop Turning Eggs
Timing is everything in incubation. For most poultry species, turning is required up until about two to three days before the expected hatch date. This period is known as the lockdown stage.
- Chickens: Stop turning on day 18 of a 21-day incubation.
- Ducks: Stop turning on day 25 of a 28-day incubation.
- Turkeys: Stop turning on day 25 of a 28-day incubation.
- Quail: Stop turning on day 14 of a 17–18 day incubation.
During this lockdown stage, chicks need to position themselves correctly for hatching. If eggs continue to be turned, embryos can struggle to orient, making it difficult for them to pip (break through the shell).
🐥 Why Stopping Egg Turning Matters Before Hatch
1. Correct Positioning for Pipping
Chicks must rotate inside the shell so their head rests under the right wing, close to the air cell. This positioning allows them to pip the air sac and then the outer shell.
If turning continues, chicks may:
- End up facing the wrong direction.
- Struggle to reach the air sac.
- Suffocate before hatching.
2. Air Cell Development
The air cell inside the egg expands in the final days as moisture evaporates. Chicks rely on this air cell for their first breath before breaking the shell. Constant turning can disturb the air cell, making it harder for chicks to transition from internal to external breathing.
3. Muscle Strength and Energy Conservation
By the last three days, embryos are fully developed. Instead of constant repositioning, they need to conserve energy for hatching. If eggs are still being turned, chicks waste unnecessary energy trying to stabilize themselves inside. This leads to weak hatching attempts or chicks dying mid-pip.
4. Risk of Malpositions
A malpositioned chick is one that cannot orient properly inside the shell. Common malpositions include:
- Head away from the air cell.
- Head under the left wing instead of the right.
- Feet over the head, blocking pipping.
5. Reduced Hatchability
Research and farm records consistently show that failing to stop turning reduces hatch rates by 10–20%. Even when chicks do hatch, they may emerge weaker, with higher post-hatch mortality.
🌡️ Environmental Adjustments During Lockdown
Stopping egg turning is not just about halting movement—it’s part of a larger process called lockdown management. Once you stop turning, other incubation parameters also need adjustment.
- Humidity Increase: Raise relative humidity to 65–70% (for chickens). This softens the shell and membranes, making pipping easier.
- Stable Temperature: Maintain incubation temperature (37.5°C / 99.5°F), but avoid opening the incubator. Temperature drops during this stage can delay hatch.
- No Disturbance Rule: Avoid handling eggs after lockdown. Disturbances can disorient chicks or cause premature pipping.
🐓 Farmer Experiences and Case Studies
Case 1: A Small-Scale Farm in Kenya
A farmer continued turning chicken eggs until day 20. Hatch rate dropped to 62%, with many chicks found dead fully formed but unable to pip. After adjusting practice to stop turning on day 18, hatch rate improved to 86%.
Case 2: Commercial Hatchery in Brazil
A large hatchery experimented with duck eggs, comparing two groups: one stopped turning on day 25, the other continued until hatch. The first group had 91% hatchability, while the second had 74%, with many weaklings.
Case 3: Backyard Hobbyist in the US
A hobbyist incubating quail eggs noticed that chicks were pipping at the wrong end of the egg. After research, they discovered it was due to late turning. Stopping at day 14 solved the issue completely.
📊 Lockdown Day-by-Day Management Chart (Chicken Eggs Example – Adjust for Other Birds)
| Day of Incubation | Temperature (°C/°F) | Humidity (%) | Do’s ✅ | Don’ts ❌ |
|---|---|---|---|---|
| Day 18 | 37.5°C / 99.5°F | 65% | - Stop turning eggs. - Candle eggs to check air cell development. - Add water trays or sponges to boost humidity. - Close incubator after adjustments. | - Don’t open incubator repeatedly. - Don’t reduce humidity. |
| Day 19 | 37.3–37.5°C / 99.1–99.5°F | 65–70% | - Maintain stable temperature. - Keep incubator closed to avoid moisture loss. - Watch for internal pipping (through air cell). | - Don’t disturb eggs when you see movement. - Don’t rotate or tilt. |
| Day 20 | 37.2–37.5°C / 99–99.5°F | 70% | - Expect external pipping (tiny cracks on shell). - Increase humidity slightly if shells look too dry. - Keep calm—hatch is near. | - Don’t assist chicks unless absolutely necessary. - Don’t lower humidity. |
| Day 21 (Hatch Day) | 37.0–37.2°C / 98.6–99°F | 70–75% | - Let chicks break out naturally. - Remove hatched chicks only when completely dry and fluffy. - Transfer to brooder quickly. | - Don’t open incubator too often. - Don’t rush to help chicks out of shells unless >24 hrs stuck. |
👉 For ducks/turkeys: same principles, but start lockdown at Day 25.
👉 For quail: lockdown begins Day 14.
🌍 Global Practices in Lockdown Management
- Europe: Automated hatcheries strictly program incubators to stop turning 3 days before hatch, with controlled humidity chambers.
- Asia: Many small farms rely on manual turning but often forget to stop in time, leading to lower hatch rates.
- Africa: Farmers sometimes stop too early due to fear of malpositions, but this reduces development efficiency.
- North America: Advanced hatcheries use sensors to detect air cell development and time the stop automatically.
🧪 PoultryHatch Insights & Data Analysis
From PoultryHatch surveys of 500+ farmers worldwide:
- Farms that stopped turning at the correct time had an average hatch rate of 88%, compared to 72% in farms that continued turning too long.
- Correct lockdown management reduced weak chick rates by 35%.
- Proper stopping time improved feed conversion ratio (FCR) post-hatch, as healthier chicks ate and grew more efficiently.
🔬 The Science Behind “Lockdown”
Embryology studies show that by day 18 (in chickens):
- The embryo is fully formed.
- The yolk sac begins to be absorbed.
- The chick starts moving toward the air cell.
Turning during this stage disrupts the final natural choreography that leads to hatching. This is why the last 2–3 days are called “lockdown”—the embryo must not be disturbed.
🔍 Signs You Stopped Turning at the Right Time
- Air cell is clearly visible and slightly enlarged.
- Embryos look fully developed when candled (veins almost absorbed).
- Chicks begin adjusting posture inside (you may notice subtle movement).
⚠️ What Happens If You Stop Turning Too Early
- Embryos may stick to one side of the shell.
- Deformities such as twisted necks or unabsorbed yolk sacs.
- Lower hatch rate due to uneven development.
⚠️ What Happens If You Stop Turning Too Late
- Chicks misalign (head not near air cell).
- Increased risk of “shrink-wrapping” where membrane dries before chick breaks shell.
- Exhausted chicks that die mid-pip.
🐓 Role of Humidity During Lockdown
Humidity is not just about softening shells. It also:
- Controls weight loss of the egg (ideal: 11–14% by hatch).
- Prevents membranes from becoming too tough.
- Supports proper expansion of the air cell for first breath.
🐤 Advanced Farmer Tip – Monitoring Air Cell Growth
Serious hatcheries candle eggs on Days 7, 14, and 18. By Day 18, the air cell should take up about ⅓ of the egg’s blunt end. If it’s too small → humidity has been too high. If it’s too large → humidity has been too low.
🧑🌾 Practical Farmer Checklist Before Lockdown
- Clean and refill water trays for humidity.
- Mark calendar or incubator display for lockdown start.
- Switch off automatic turner (remove trays if necessary).
- Avoid unnecessary handling once eggs are in lockdown.
- Prepare the brooder in advance so chicks have a warm, safe space once they hatch.
🐤 Practical Tips for Farmers
- Mark Calendar Clearly: Write incubation days visibly to avoid forgetting when to stop.
- Automated Turners: Use incubators with auto-stop features to prevent mistakes.
- Monitor Air Cells: Candle eggs around day 18 to ensure air cell development looks normal.
- Avoid Peeking: Curiosity can kill chicks—resist the urge to open the incubator once you stop turning.
❓ FAQs – Stopping Egg Turning Before Hatching
Q1: What happens if I forget to stop turning eggs?
A: Chicks may struggle to pip, leading to high mortality even in fully developed embryos.Q2: Can I stop turning earlier than 3 days before hatch?
A: Stopping too early can also cause developmental problems, so stick to species-specific timing.Q3: Do all bird species follow the same rule?
A: The principle is the same, but timing differs based on incubation length. Always adjust accordingly.Q4: Should I increase humidity immediately after stopping turning?
A: Yes. Humidity must be raised as soon as lockdown begins to soften shells.Q5: Can chicks still hatch if I mistakenly turned them during lockdown?
A: Some may hatch, but success rates and chick quality will be significantly lower.🐥 Conclusion – Lockdown Discipline Equals Hatching Success
Stopping egg turning before hatching is not a minor detail—it is one of the most critical steps in incubation. It allows embryos to position correctly, breathe properly, and save energy for the demanding process of breaking out of the shell.
Farmers who respect the lockdown stage consistently report higher hatchability, healthier chicks, and stronger flocks. On the other hand, neglecting this step often results in fully developed chicks dying inside the shell—one of the most frustrating losses in poultry farming.
PoultryHatch Key Takeaway: Turning eggs is essential early on, but knowing when to stop is the secret to hatching success. Mastering this balance separates struggling hatcheries from thriving ones.