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What two chickens make an ISA Brown?

The ISA Brown is a popular dual-purpose chicken breed known for its prolific egg laying and good meat production. But what two chicken breeds were crossed to create the ISA Brown? Let’s take a look at the interesting origin story of this unique chicken breed.

History of the ISA Brown

The ISA Brown was the result of crossbreeding programs in the 1970s conducted by the Institute of Animal Science in Czechoslovakia. Researchers crossed Rhode Island Red roosters with Rhode Island White hens to produce a sex-linked chicken that would lay a high number of large brown eggs.

The first generation cross was referred to as the Golden Comet. By continuing to crossbreed the Golden Comets, researchers developed the Warren brown and finally the ISA Brown, which was named after the Institute of Animal Science (ISA in Czech).

The ISA Brown was brought to the United States in the 1980s by private breeders and soon gained popularity for its stellar egg production. It continues to be one of the most common brown egg laying breeds used in commercial operations today.

Rhode Island Red

One of the parent breeds used to create the ISA Brown was the Rhode Island Red. This is an American breed that originated in Adamsville, Rhode Island in the late 1800s. Rhode Island Reds are known for their rich, mahogany plumage and excellent egg laying skills.

Some key facts about Rhode Island Reds:

  • Primarily raised for eggs, but also used for meat
  • Excellent foragers that are hardy and tolerate confinement well
  • Docile temperament and hardy constitution
  • Lay 200-300 brown eggs per year
  • Mature early and are very productive

The rich red plumage and early maturity of the Rhode Island Red was passed down to the ISA Brown, contributing to its popularity and productivity.

Rhode Island White

The other parent breed used to develop the ISA Brown was the Rhode Island White. Like the Rhode Island Red, this breed was also developed in the late 1800s in Adamsville, Rhode Island.

Here are some key facts about Rhode Island Whites:

  • Raised primarily for egg production
  • Lay 200-300 large brown eggs per year
  • Excellent forager that is cold hardy
  • Docile personality good for backyard flocks
  • Medium-sized dual purpose breed

The Rhode Island White contributed its prolific egg laying ability and white plumage to the ISA Brown. The contrast of white and red feathers is a striking signature of the ISA Brown breed.

Crossbreeding the Rhode Island Red and Rhode Island White

By crossing the Rhode Island Red rooster with the Rhode Island White hen, researchers were able to develop a sex-linked chicken. This means the gender of the chicks can be determined by their feather color at hatching.

Here is how the sex-linking works:

  • Rhode Island Red roosters have the genotype “XRXr”
  • Rhode Island White hens have the genotype “XrXr”
  • Male chicks inherit one X chromosome from the hen and one r chromosome from the rooster, giving them the genotype “XrY”
  • This produces male chicks with the red Rhode Island Red plumage
  • Female chicks inherit one X chromosome from each parent, giving them the genotype “XRXr”
  • This produces female chicks with the black and white Rhode Island White plumage

This allowed easy sexing of chicks to determine pullets and cockerels straight from the shell, saving time and expense in the hatchery.

Characteristics of the ISA Brown

By continuing to crossbreed the offspring of Rhode Island Reds and Rhode Island Whites, the ideal dual purpose brown egg layer was developed – the ISA Brown. Here are some of the key characteristics of this breed:

Appearance Sex-linked plumage; males have red hackles and tails, females have black and white barred pattern
Size 6-7.5 lbs for hens, 8-9 lbs for roosters
Temperament Friendly and docile
Egg Production 280-320 brown eggs per year
Egg Size Large to extra large
Egg Color Rich brown
Dual Purpose Good meat production from surplus cockerels

The ISA Brown continues to be one of the most efficient and productive brown egg layers used commercially throughout the world. Their high feed-to-egg conversion ratio and hardy, docile temperament makes them an excellent choice for both small farms and large scale operations.

The ISA Brown Today

The ISA Brown has many advantages that have led to its popularity as a commercial egg layer, including:

  • Sex-linked chicks for easy gender identification
  • High rate of lay – typically over 300 eggs per year
  • Efficient feed to egg conversion ratio
  • Ability to produce well when confined
  • Docile temperament perfect for commercial settings
  • Hardy and disease resistant

For these reasons, the ISA Brown is the most popular layer breed used by commercial egg producers throughout the world. They began gaining popularity in the United States in the 1980s and their efficient egg laying skills quickly made them a favorite.

Today, the ISA Brown accounts for about 60-65% of all commercial layers worldwide. They are found in large factory farms as well as backyard flocks. While they tend to be more expensive chicks to purchase than other breeds, their stellar egg production makes them worth the investment for many flock owners.

Finding ISA Browns

ISA Browns are available from most hatcheries that supply to commercial poultry operations. However, it can be more challenging to find smaller numbers of ISA Brown chicks from local feed stores or online hatcheries catered towards small backyard flocks. Here are some tips for sourcing ISA Browns:

  • Check with local feed stores to see if they can special order ISA Brown chicks
  • Look for hatcheries that supply to commercial farms – they will likely have ISA Browns
  • Be prepared to order a larger minimum number of chicks, usually 25-50
  • Consider buying day old ISA pullets from a local producer rather than chicks
  • Join poultry forums and Facebook groups to connect with ISA Brown breeders in your area

With some persistence and planning, you should be able to locate ISA Brown chicks or pullets to add this outstanding production breed to your flock!

Raising ISA Browns

Here are some tips for successfully raising ISA Browns in your flock:

  • Brooding: Ensure proper temperature, ventilation, litter conditions and clean water for chicks. ISA Browns thrive at 65°F for the first week and then 5°F lower each week until fully feathered.
  • Coop: ISA Browns are hardy birds that tolerate confinement well, but provide at least 1.5-2 square feet per bird inside the coop and 8-10 square feet per bird in the run.
  • Feed: Follow a complete layer feed schedule offering starter feed for pullets under 17 weeks old, then transition to layer feed. Provide insoluble granite grit.
  • Supplements: In addition to layer feed, offer oyster shell for calcium and a flock block for additional nutrients.
  • Health: Practice good biosecurity. Quarantine new birds. Provide vaccination and prompt treatment for illness.

With proper care, an ISA Brown home flock can provide a bountiful supply of large brown eggs for years to come!

Breeding ISA Browns

The ISA Brown is uniquely designed for commercial egg laying performance. While their sex-linked genes make hatchery operations more efficient, it can be trickier to breed pure ISA Brown birds in a small flock setting. Here are some tips if you want to hatch ISA Brown chicks:

  • Purchase birds from reputable breeders to ensure they are pure ISA Browns
  • Use only ISA Brown roosters over ISA Brown hens, avoid crossing colors
  • Understand not all chicks will have the sex-linked color patterns
  • Select the best egg laying females each generation to breed from
  • Cull non-sex-linked chicks to keep flock genetics pure

While challenging, it is possible to maintain ISA Brown breeding stock for a small farm or backyard flock with diligent selection and culling over generations.

Alternatives to ISA Browns

For small flocks owners who want prolific brown egg layers but can’t source ISA Browns, there are a couple alternative breeds to consider:

Black Sex Link

Like ISA Browns, Black Sex Links are a cross between a Rhode Island Red rooster and Rhode Island White hen. This produces pullets with black and white plumage. They share the excellent egg laying traits of the ISA Brown.

Easter Eggers

Easter Eggers are a mixed breed that often contains Ameraucana genetics. While they don’t have the commercial laying efficiency of ISA Browns, they do lay about 250 colorful light brown eggs per year.


The Marans is a heritage breed from France that lays medium sized deep chocolate brown eggs. They have a more moderate output of about 150-200 eggs per year.

While none can quite match the ISA Brown’s superstar skills, these breeds are good alternatives for backyard flocks focused on brown eggs.


The ISA Brown was created by crossing Rhode Island Red roosters and Rhode Island White hens in the 1970s by Czechoslovakian researchers. This dual purpose breed has gone on to become the most popular commercial layer breed globally due to its prolific egg laying, efficient feed conversion, hardiness and docile temperament. While they can be challenging to source for small flocks, the ISA Brown is certainly a star when it comes to producing bountiful quantities of large brown eggs.