If you keep chickens or are curious about eggs, you might wonder: how do you know if a chicken egg is fertilised? Whether you’re hoping to hatch chicks or just want to understand more about the eggs you collect, this guide will walk you through the simple ways to tell if an egg is fertilised — without any complicated science!
What Does “Fertilised” Mean?
A fertilised egg means that a rooster has mated with a hen, and the egg contains a developing embryo. This is different from the eggs you usually buy at the store, which are typically unfertilised because they come from hens without roosters. Fertilised eggs have the potential to hatch into chicks if incubated properly.
How Does Fertilisation Happen?
Roosters fertilise eggs by mating with hens in a process called a “cloaca kiss,” where their cloacas touch and sperm is transferred. The hen can store this sperm for several days, fertilising eggs that form afterward. So, even if a rooster isn’t always present, a hen can lay fertilised eggs for up to three weeks after mating.
Ways to Tell If a Chicken Egg Is Fertilised
1. Candling the Egg (Using a Light)
Candling is a popular, non-invasive way to check if an egg is fertilised. You hold the egg up to a bright light (like a flashlight) in a dark room and look inside the shell.
– Fertilised eggs will show a small dark spot (the embryo) and sometimes spider-like veins spreading out from it.
– Unfertilised eggs will appear clear or just show the yolk without any dark spots or veins.
Candling is especially useful if you plan to incubate the eggs and want to monitor embryo development over several days.
2. Cracking the Egg Open
If you don’t mind breaking the egg, this is the easiest and most reliable method.
– Look for a small white spot on the yolk called the germinal disc.
– In an unfertilised egg, this spot is small and plain (called a blastodisc).
– In a fertilised egg, the germinal disc looks like a bullseye or target — a white circle with another ring around it (called a blastoderm). This indicates the start of embryo development.
If you see this bullseye pattern, the egg is fertilised and could hatch if incubated.
3. Observing the Egg’s Appearance
Sometimes, fertilised eggs look a bit different even before cracking or candling.
– Fertilised eggs may appear more opaque or cloudier compared to unfertilised eggs, which tend to be more translucent.
– However, this method is not very accurate on its own.
What About Eggs Without Roosters?
If there is no rooster in your flock, the eggs will never be fertilised. Hens lay eggs regardless of mating, but without fertilisation, these eggs won’t develop into chicks.
Why Does It Matter?
Knowing if an egg is fertilised is important for:
– Hatchers who want to grow chicks.
– Backyard chicken keepers curious about their flock’s breeding.
– Farmers managing breeding stock.
If you want to hatch chicks, fertilised eggs need to be incubated under the right conditions. Candling during incubation helps track embryo growth and identify if the egg is developing properly.
Tips for Candling Success
– Do it in a dark room with a bright flashlight.
– Hold the egg’s larger end up to the light.
– Look for the dark embryo spot and veins around day 4 of incubation.
– Repeat candling on days 10 and 17 to monitor progress.
Summary
– Fertilised eggs come from hens that have mated with roosters.
– You can tell if an egg is fertilised by candling (looking inside with a light), cracking it open to see the germinal disc, or sometimes by the egg’s opacity.
– The bullseye pattern on the yolk after cracking is the clearest sign of fertilisation.
– Without a rooster, eggs won’t be fertilised.
– Candling is the best non-destructive way to check if eggs are fertile and developing.
Fertilised eggs hold the promise of new life, and knowing how to identify them helps you care for your flock or simply satisfy your curiosity about what’s inside those shells.
Enjoy your chicken-keeping adventure!
Knowing if a chicken egg is fertilised is straightforward once you know what to look for—whether by candling or checking the yolk. With these tips, you’ll be a pro in no time!