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How Old Does a Rooster Have to Be to Fertilize Eggs?Does Breed Matter?

Backyard chickens are becoming a growing trend among individuals wanting to provide their families with fresh eggs. 

A rooster is not needed for a hen to produce eggs; however, he will protect his flock. Around six months, a rooster is usually mature enough to fertilize eggs, although breed can factor into this.

Understanding the development of your rooster is essential to understanding his behavior and providing the ultimate care, as well as hatching chicks from your flock.

How Old Does a Rooster Have to Be to Fertilize a Hen? 

By around four months of age, a rooster will begin to show signs of sexual maturity. He may start crowing and strutting around the barnyard.

If you have more than one rooster, you may notice fighting, also known as sparring. This behavior is the establishment of the pecking order, and even hens do it. Some show signs of maturing as early as ten weeks.

Factors that can affect whether a rooster will fertilize a hen:

  • Inexperienced rooster 
  • An older rooster is not letting him mate
  • Inexperienced hens
  • Comb-type: single combs have better fertility.
  • Factors such as feathers
  • Environmental factors
  • Health factors

Most individuals will mature closer to six months, and larger breeds take longer to develop than smaller bantam breeds. If you find your rooster crowing all day, that is a good indicator of maturity too.

Does breed matter?

Like with any animal, different breeds have different traits and maturation rates than others.

Roosters from larger species typically become fertile later, some as late as eight months.

Breeds such as Wyandotte, Cochin, and Brahmas usually mature closer to eight months, and this is due to their size.

Comb-type, feathering type, and other factors can also impact whether the rooster can fertilize a hen. 

Breeds with rose combs like Wyandottes and Sebrights typically have fertility issues. Some Wyandotte breeders will purposely select some chickens with a single comb rather than the rose comb to breed into the lines to increase their hatch rates.

Orpingtons and Cochins are heavily feathered, and this can also affect if the hen is fertilized. Trimming feathers around the vent helps prevent any build-up of feces that might occur.

Breeds with crests such as Silkies and Polish may have issues seeing and thus breed less.

Some people will use hair ties to tie the crests out of the face of their chickens or trim around their eyes. Doing this can also be helpful for the bird by allowing them to see better and thus providing better protection against predators.


Another issue is inbreeding. Some populations are heavily inbred, which can negatively affect fertility and the health of the birds.

Dominant roosters are more fertile, and this is due to how chickens mate; the hen needs to be submissive to the rooster to accept him. 

Some people choose to inseminate their birds artificially, which is done carefully to ensure the viability of the sperm is kept high. A syringe is used to collect the semen from the desired rooster, and then the sperm is placed onto the hen’s cloaca. 

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At What Age Does a Rooster Stop Being Fertile?

At What Age Does a Rooster Stop Being Fertile

Like males from many other species, roosters are fertile until they die. Though, fertility can decrease as they age. 

Peak fertility is between two and four years of age. Life expectancy is around eight to twelve years, though many choose to swap out roosters for younger and more genetically diverse individuals. 

Aging can also cause physical issues. A rooster may begin showing signs of aging and will start to stop fertilizing hens as well. If there are multiple roosters, a younger rooster may become more dominant over the older one and take the hens for himself. 

Injuries could also affect the rooster’s ability to mate. An injury to his leg, such as an improperly healed break, would cause him not to mount a hen, thus reducing his fertility. 

Three Ways to Increase Fertility in Roosters

Fertility is a complicated matter. Unlike humans, we do not test the sperm count of roosters, which can make testing for fertility a bit more complicated; however, there are ways to make it possible.

Provide a proper diet

With any animal, diet is vital for reproduction. Reproduction is considered non-essential by the body, and thus, will not be prioritized by the body. Without proper nutrition, the rooster’s body will put its resources towards other systems. 

Having an overweight rooster can also negatively impact fertility. Breeds such as Cornish are bred to put on weight quickly and can have issues mating. 

Water is essential to chickens. Make sure your chickens have fresh and clean water available at all times. 

Provide proper medical care

Chickens who are sick will not mate. Like a cat or a dog, chickens need to have medical care done. Routinely deworming, treating external parasites like mites, and doing overall health checks are crucial to maintaining a healthy flock.

It is suggested you deworm your chickens twice a year. Make sure to properly read the labels on all dewormers as most have a withdrawal period, and you cannot eat the eggs during this time. Some claim natural wormers like pumpkin seeds work as well. 

There are some vaccines available on the market for chickens. These help prevent diseases chickens are susceptible to; however, many need to be administered when the chickens are a day old. 

Keeping a clean living area is also crucial to maintaining healthy chickens. Chickens will get sick without a dry and clean coop, and keeping a coop free from drafts and rain is essential to birds’ health. 

A coop should be secure, adequately ventilated, and free of rodents. These factors will help increase the fertility of your rooster.


Seasons can also affect the fertility of roosters. Hens lay eggs less when there is not as much daylight available, and they need 14 hours a day to lay eggs, so naturally, roosters will breed less. 

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There are a few different options to fix this. You can either allow for this natural break or provide artificial light inside the coop. 

How Many Hens Can a Rooster Fertilize a Day?

The rooster to hen ratio is 1:6. However, this is also a determinant of the rooster’s overall personality.

A calmer rooster is less likely to mate with more than a few hens. Some people choose to do a 1:2 ratio when breeding to ensure the best fertility.

Usually, a rooster will pick a few hens as his favorite. To combat any feather loss, you can put a special saddle on the hen.

This can also mean only some of the hens will be fertile. Watch to see if he is breeding every hen, or you may need to remove some of his favorites to get fertile eggs from all the hens.

Sperm can live anywhere between 10 to 14 days inside the hen’s reproductive tract, and the hen can also reject sperm from a rooster. 

A fertilized egg is safe to eat and is no different than a non-fertilized one. As long as the eggs are fresh, they are safe for consumption. 

Checking eggs for fertility

There are only two ways to see if an egg is fertile. One is trying to hatch the egg either under a hen or inside an incubator.

The other is to crack the egg open. A fertilized egg will have what is called a bullseye. A bullseye is a small white ring in the yolk of the egg. 

Incubating eggs

Eggs should be stored pointy side down at room temperature. Fresh unwashed eggs have a special coating that prevents them from spoiling. You can keep eggs for up to five days before incubating.

Chickens incubate for around 21 days, and they should be set at 99.5 to 100 degrees Fahrenheit with 50% humidity and turned every four hours. Most incubators on the market come with the option to purchase an automatic egg turner as well. 

Incubating eggs

Hens will also become broody. Some breeds, such as Silkies, are excellent mothers. Many prefer allowing hens to hatch for them, but the broody hen will not lay eggs while broody and raising their chicks.


A rooster is fertile between 4-8 months of age, and larger breeds like Brahmas can take closer to eight months to mature. A rooster never becomes completely infertile. However, his fertility can decrease with age.

A rooster should have somewhere between four and six hens; however, this depends on the rooster’s personality.

Hatching your chickens can be a rewarding experience, and knowledge of the reproductive nature of roosters is necessary to be successful. 

If you want to continue breeding chickens for various reasons, you need to have the best fertility in your flock. This means providing the best care for your animals and selecting breeding stock with the best traits to pass on to future generations.

Chickens are lovely backyard pets! They come with the added benefit of eggs, and if you are curious about breeding and hatching chickens, a rooster is a must-have. A fertile rooster is essential to have to hatch eggs.