Hens don’t need a rooster to lay eggs, but they do need one to lay eggs that have been fertilized. Chickens are different from mammals in a lot of ways when it comes to their anatomy and therefore their reproductive system. Let’s talk about how eggs are fertilized by chickens.
When roosters mate with hens, they transfer their sperm through cloacal contact and not by penetration. The first fertile egg is laid between 36-48 hours after mating. So an egg laid the day the chickens mate won’t be fertile and an egg laid three days later is fertile.
How is a Chicken Egg Fertilized? A Step-by-Step Explanation
Many people are curious about how a chicken egg becomes fertilized and develops into a chick The process involves a series of intricate steps and coordination between the hen and the rooster By understanding the physiology of chickens, we can gain insight into this remarkable reproductive process.
The Cycle Starts with the Rooster
The cycle begins when a rooster reaches sexual maturity, usually around 5-6 months of age. Like most male animals, roosters possess an innate drive to mate and pass on their genes. A rooster will begin by identifying receptive hens and performing a courting ritual called “tidbitting.” He makes food calls to attract a hen, drops a small treat for her, and repeats the process until she is near.
Once the hen is close by, the rooster circles around her, lowering his wing closest to her and dragging it along the ground. He may also pick up objects like food or feathers and drop them in front of her. If interested, the hen will crouch down submissively to signal her readiness to mate.
Mating and Insemination
The rooster will get on top of the hen from behind and grab her wings with his own. The male lines up their cloacae, which are the openings to their reproductive tracts, and inserts his phallus to transfer sperm into the hen’s vagina. The actual act lasts only a few seconds.
The rooster’s semen contains over 100 million sperm cells, evolved to survive the difficult journey to fertilize an egg. The hen’s oviduct stores the sperm in specialized glands just inside the opening. Here, they can remain viable for up to 4 weeks.
Ovulation and Fertilization
Hens ovulate eggs regularly on their own cycles, even if they haven’t been inseminated recently. Some sperm swim to meet the egg as it flows from the ovary into the oviduct. One sperm cell can get inside the egg and merge its DNA with that of the egg’s nucleus. A zygote is the new cell that is made, and it has all the genetic information it needs to grow into a chick.
Egg Development
The fertilized egg moves down the oviduct for 25 hours, picking up nutrients and layers of protection along the way. Calcium carbonate is used to make the shell in the lower oviduct, which seals the egg’s contents. The finished egg goes into the nest through the hen’s cloaca. It can take up to 10 days for the first fertile egg to be laid after mating.
Incubation and Hatching
If incubated, the zygote resumes dividing and developing into an embryo attached to the yolk for nutrition. Body parts rapidly take shape. Around day 19, the chick uses its egg tooth to peck a hole in the air cell. It takes its first breaths and starts to call to its mother. On day 21, the chick fully emerges wet and exhausted, ready to be brooded under its mother’s warmth.
Do Fertilized Eggs Look Different?
Fertilized eggs do not look obviously different upon first examining them. Without cracking the egg, you can shine a light into the egg and see spider veins and a dark area if the embryo has started to develop. An egg that hasn’t been fertilized will look translucent.
You can look for the germ spot in the yolks of the eggs after they have been cracked open. The germ spot is a white circle just outside of the center of the yolk. A fertile egg will have a larger white spot with a clear space in the center. An infertile egg will have a smaller white spot. This can be hard to identify if you aren’t comparing a fertile yolk with an infertile yolk.
What is The Cloaca?
A hen has just one opening where both feces and eggs exit the body. This is also where sperm enters. The rooster’s cloaca passes feces and transfers sperm to the hen.
Chickens don’t urinate! They don’t have bladders or urethras, liquids exit with their poop through the cloaca. There is much less liquid urine in their coop, so it stays dry much better than if they were peeing on their bedding all day. Their liquid feces are able to dry quickly.
When the hen and rooster make cloacal contact, sperm enter the oviduct and are stored in glands that can store over half a million sperm. Sperm can stay alive in the storage glands for up to 3 weeks fertilizing eggs. An egg is fertilized about 24 hours before it’s laid.
How eggs are fertilized by chickens is more similar to mammals than you might think. Considering the fertilizing happens inside of their body even though the growing happens outside of their body!.
How do chicken eggs get fertilized? *More Than You Ever Wanted To Know*
FAQ
How do farmers know if a chicken egg is fertilized?
Farmers can determine if a chicken egg is fertilized through candling or by cracking the egg open and observing the yolk. Candling involves shining a bright light through the egg in a dark room to see if there are signs of development, such as blood vessels or a dark spot (the embryo).
Are chicken eggs fertilized after they are laid?
No, chicken eggs are not fertilized after they are laid. Fertilization happens inside the hen’s body, before the egg is even formed. The rooster deposits sperm during mating, and the sperm travels to meet the egg in the hen’s oviduct, where fertilization occurs.
How does a rooster fertilize an egg?
A rooster fertilizes an egg laid by a hen through a process called cloacal contact, also known as a “cloacal kiss.” During mating, the rooster’s and hen’s cloacas move together, touching and transferring sperm.
Are fertilized eggs safe to eat?
Yes, you can eat both fertilized and unfertilized chicken eggs as long as they haven’t been grown in a nest. The presence of a fertilized germinal disc (the bullseye spot on the yolk) doesn’t affect the egg’s safety or taste.
How do chickens fertilize eggs?
Chickens — like other birds — lay fertilized eggs via sexual reproduction. Depending on the breed of chicken, a hen will begin laying eggs between five and seven months of age.
How long does it take a chicken egg to be fertilized?
Eggs are fertilized 24 hours before they are laid. It takes 24 hours for an egg to leave the ovary and be laid out the vent. How do you know if a chicken egg is fertilized? Hold a light up behind an egg and look through it – use a flashlight, candle, or lighter.
Are chicken eggs fertilized?
Most chicken eggs people eat are not fertilized. Hens are raised without roosters on most commercial egg farms. This means that the eggs the hens lay can’t be fertilized. Fertilized eggs are more common in backyard flocks where roosters are present. So, when you crack open an egg from the grocery store, it’s most likely unfertilized.
How does a rooster fertilize a chicken?
A chicken’s egg is usually fertilized by a rooster when the hen lays the egg. The rooster will mount the hen and pass sperm into her oviduct, which is the tube that connects her ovary to her uterus. The sperm will then travel up the oviduct and meet the egg, which is released from the hen’s ovary.
How does chicken egg fertilization work?
The egg also receives a coating of bloom, which is a thin layer of protein that seals the pores of the shell and prevents bacteria from entering. The egg is finally laid through the cloaca and into a nest or incubator. Watch the chicken egg fertilization process below.
How does a chicken reproduce?
This is the chicken reproduction system in the following diagram. An egg is fertilized by the sperm in the Infundibulum, not long after the yolk has been released from the ovary. Once an egg is released, this is the process it undergoes: It is quite extraordinary and something to marvel at – like most things in the world when it comes down to it!