Incubation Logbook: Measuring Performance, Fertility and Hatchability

The answer to "why was the hatch low this time?" is often hidden in your past records. You can't improve what you don't measure, and memory is unreliable. A simple incubation logbook, kept consistently, shows which setting worked, whether the problem is in the coop or the machine, and how to get a little better with each batch. This guide explains what to record, which rates to calculate, and how to diagnose the problem from your records.

Why Keep Records?

Incubation is a process affected by many variables at once (temperature, humidity, turning, egg age, fertility). Without records, you can't get past guessing at the cause of a low hatch. Noting a few numbers narrows the source of the problem mathematically and turns each batch into an experiment you learn from.

What to Record for Each Batch

• Starting information: Set date, species, egg count, egg source (which flock/breeders), how many days the eggs were stored.
• Settings: Target and measured temperature-humidity, lockdown date and hatch humidity.
• Candling results: The number of fertile and infertile (clear) eggs at each candling, and the number of dead embryos culled.
• Hatch results: The number of healthy chicks hatched, the number that couldn't break out of the shell (dead in shell), and the hatch date.
• Notes: Events specific to that batch, such as a power cut, a temperature spike or shipped eggs.

Three Key Rates to Calculate

These three rates almost directly tell you where the problem is:

• Fertility (%) = Fertile eggs ÷ Total eggs set × 100. Determined at candling; it shows the performance of your coop's breeders.
• Hatchability (%) = Chicks hatched ÷ Fertile eggs × 100. It shows how many of the fertile eggs turned into live chicks — that is, the success of the incubation conditions.
• Hatch rate (%) = Chicks hatched ÷ Total eggs set × 100. The overall success; the combination of fertility and hatchability.

Diagnosing the Problem from Records

Separating the two rates immediately narrows the source of the problem:

• If fertility is low (many clear eggs): The problem isn't in the machine but in the coop — male ratio, breeder age, nutrition or season. The solution is in our fertility guide.
• If fertility is high but hatchability is low (fertile but dead in shell): The problem is in the incubation conditions — temperature, humidity, turning or ventilation. See 10 reasons eggs don't hatch and our humidity guide.
• The time of death is a clue: Early deaths (first days) are usually temperature, jarring or genetics; late deaths (final days, dead in shell) are usually a humidity, ventilation or lockdown problem. You can only tell these apart with candling and records.

Examining Unhatched Eggs (Break-Out)

Carefully cracking open and examining the eggs that didn't hatch after the hatch is over is the most valuable feedback:

• Completely clear (no embryo): Infertile — a fertility problem.
• Blood ring or an embryo that stopped early: Early-stage death — temperature, storage or jarring.
• A developed chick that couldn't break the shell: Late-stage death — usually humidity/ventilation or lockdown; look at the air cell and membrane state.

Record this examination in your log; after a few batches you'll clearly see which error recurs. What to look for is covered day by day in our candling guide.

Improving from Batch to Batch

The real power of record-keeping is seeing the trend, not a single batch. When you change one variable (say, humidity) and compare the result with the previous batch, you learn objectively whether that change actually helped. Change one thing at a time so you can isolate what made the difference.

How to Keep the Record

A simple notebook, spreadsheet or phone app is enough. The KuluçkaTakip app records the species and start date for each batch and calculates and reminds you of the turning, candling, lockdown and hatch days — so you don't miss the critical days and you keep each batch's record together.

The Most Common Mistakes

• Keeping no records and leaving the cause of a low hatch to guesswork.
• Not separating fertility from hatchability (not knowing whether the problem is in the coop or the machine).
• Throwing out unhatched eggs without examining them (missing the most valuable feedback).
• Changing several variables at once in a batch and being unable to isolate what worked.
• Not noting events like a power cut or a temperature spike.

Well-kept records are the way to apply all the guides on this blog to your own incubation: when you combine the fertility, humidity, troubleshooting and calibration guides with your records, your hatch climbs a little higher every batch.