Hatchability and Fertility: Practical Benchmarks for a Backyard Breeder

After a hatch, most backyard keepers say something like "I got seven out of twelve" and leave it at that. Seven out of twelve could mean very different things. It might mean five eggs were infertile, or it might mean a perfect-fertility flock lost embryos during incubation. Without knowing which, you cannot fix anything. This article explains the standard measures, what the industry treats as a good result and how a small breeder can track their own numbers.

A caution up front: I could not find a published, reliable benchmark for backyard hatches of Speckled Sussex or similar heritage breeds, so this article does not offer a magic target. It offers a method. For help finding breeders and equipment near you, agriculture.directory can help you find farms in your area.

Three Numbers That Mean Different Things

ThePoultrySite's article Do We Understand Hatch of Fertiles Correctly? defines the terms hatcheries use:

• Hatchability: the percentage of hatching eggs that produce chicks. Chicks divided by eggs set, times 100.
• Fertility: the share of eggs that were actually fertilized. The article says it is estimated by breaking out a sample of clear eggs, and that candling alone is not enough because early dead embryos can be mistaken for infertile eggs.
• Hatch of fertile: chicks divided by fertile eggs, times 100. The article calls this the most reliable measure of hatchery performance, with a quote that no skill or technology can hatch chicks from infertile eggs.

The same article says 95 percent is the generally accepted standard for good hatch of fertile performance in a hatchery. Treat that as a ceiling for a professional operation with controlled equipment, not as a promise for a backyard setting. A backyard breeder with a small cabinet incubator, eggs from a mixed-age flock and the occasional power flicker will often see lower numbers, and that is not a failure. It just means you need your own baseline.

How to Track Your Own Numbers

1. Record eggs set. Note the date, the pen, the cock and the hens, and how long each egg was stored.
2. Candle after day 10. The University of Maryland fact sheet Hatching Eggs at Home advises starting after that point. Remove clear eggs and note how many.
3. Break out the clears. Open each one. A clear egg with no sign of development is infertile. One with a tiny blood ring or a dark spot is an early dead embryo.
4. Count the hatch. Record how many chicks hatched and how many were strong and healthy.
5. Open the failures. After the hatch, crack unhatched eggs and note whether the chick was fully formed, partly formed or died early.
6. Do the arithmetic. Fertility is fertile eggs over eggs set. Hatch of fertile is chicks over fertile eggs. Hatchability is chicks over eggs set.

Keep a simple notebook or spreadsheet, and compare across hatches. After three or four, patterns show up.

Diagnosing the Loss

Where the losses fall tells you where to look.

Low fertility (many truly infertile eggs)

This points to the breeding pen, not the incubator. Check the rooster's health and age, how many hens he has, how long he has been with them and whether hens are being bullied away from him. Our guide to roosters and fertility covers ratios and egg handling. ThePoultrySite also publishes troubleshooting notes for flock fertility problems that are useful reading, though written with commercial flocks in mind.

Good fertility but early embryo deaths

Early deaths often point to egg handling before setting or to incubator conditions in the first week. Look at storage time and temperature, and whether eggs were washed or chilled. The Maryland sheet advises storing eggs for no more than seven days, at about 65 to 70 degrees Fahrenheit, unwashed and big end up. Check your incubator's temperature with a separate thermometer.

Deaths late in incubation or at hatching

Late losses can reflect humidity, temperature swings, poor ventilation or opening the incubator during hatching. Review your lockdown routine, described in our article on incubating Speckled Sussex eggs. I will not claim that any one of these causes any one symptom, since several overlap. If you see repeated, unexplained losses, an extension office or an experienced local poultry keeper may spot the problem faster than you can.

Chicks hatch but do not thrive

Weak chicks can come from incubation problems, but also from poor brooding. Our guide to brooding covers the first month. Do not assume the incubator is to blame.

Set Reasonable Goals

• Run each setting the same way for several hatches before changing anything.
• Change one thing at a time, so you know what helped.
• Compare each hatch to your own average, not to a number from a hatchery.
• Do not set eggs from sick or very old birds, or eggs that are cracked, misshapen or dirty.

Heritage breeders have another reason to track numbers. If one pen consistently gives poor fertility or hatchability, that may reflect inbreeding or poor stock, and it may be time to bring in unrelated birds, as discussed in our guide to selecting breeding stock. You can find breeder directories through the Livestock Conservancy.

The Takeaway

Do not chase a single percentage. Measure fertility and hatch of fertile separately, keep records, and let the pattern tell you where the problem lies. Good records turn a hatch from a gamble into an experiment. For a little country humor about the odds of farm life, farm.fm's piece on commodity reports is worth a smile.