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Autosexing Poultry

Autosexing Chicken Cream Legbar Hen
A Cream Legbar hen, an autosexing poultry breed.

Autosexing poultry breeds are particularly useful to poultry fanciers who are short on space to rear birds or for those of us that want to keep rearing costs down. In this article, you will learn what autosexing is, where it comes from, the difference between autosexing and sex linkage and which chickens and geese are classified as autosexing breeds.

What is Autosexing?

Autosexing breeds are pure breeds of poultry that have different coloured male and female young as day-olds. This is a highly desirable characteristic so that females can be selected and raised as (in the case of chickens) guaranteed pullets, keeping feed costs down.

Several poultry breeds will auto-sex, the Cream Legbar being a well-known example. As a result, the offspring will breed true and pass on the autosexing quality.

Purebred Cuckoo Marans are almost an Autosexing breed because the male chicks are usually lighter in colour than the females, although this isn’t 100% accurate. 

Male and Female Cuckoo Marans Chicks

How were Autosexing breeds created?

Professor Reginald Punnett and Michael Pease led a team at the University of Cambridge in the UK who was instrumental in studying autosexing poultry during the 1920s that came up with a theory they later proved.

By accident, they discovered that day-old chicks could be sexed when the barring gene was crossed into breeds with solid plumage colours, except for black. 

Examples of breeds carrying the barring gene are Cuckoo Marans and Barred Plymouth Rocks. If these birds didn’t carry the barring gene, they would both be black.

Punnett’s theory was that the gene responsible for barred colour patterns acted differently in male and female chicks. As a result, males received two barred genes whilst females only one, which meant the males would be lighter.

Punnett exhibited the Gold Cambar (the World’s first autosexing chicken breed) at the World Poultry Congress in 1930.

Their research was so important; they were even funded during the Second World War. At this time, only pure-breeds were raised on poultry farms to produce eggs. Autosexing breeds of poultry were going to revolutionise poultry farming.

Or were they?

A revolution for poultry farming?

Whilst being able to sex chicks as they were born by their down colour was set to revolutionise the poultry industry, it did not happen. The autosexing breeds were seldom the best layers. While the team subsequently did a lot of work to improve this, the poultry industry took a sudden sharp turn towards higher production, greater feed efficiencies and factory farming with Hybrid chickens.

These birds descended from purebred stock could also be sexed as day-olds thanks to sex linkage.

Sex Linkage

Sex-linked birds can be sexed as day-old chicks by their different appearances like the autosexing breeds, and this is what is used these days extensively on commercial poultry farms.

Sex linkage is when two different breeds of (purebred) birds are crossed. For example, the Bovan Nera (AKA Black Rock, Black Star) are a sex-linked cross of the Rhode Island Red X Barred Plymouth Rock. Another popular cross is the Rhode Island Red X Light Sussex.

The offspring will not breed true from these sex-linked crosses.

RIR X Light Sussex Sex Linked Chicks
RIR X Light Sussex cross showing the difference between male and female chicks.
Photo courtesy of Grant Brereton.

List of autosexing chicken breeds

Here is a list of the autosexing chicken breeds. Most of these are either extinct or extremely rare these days. The most popular and easily obtainable is the Cream Legbar, which have probably remained popular with backyard chicken keepers because of their blue eggs.

  • Amrock
  • Ancobar
  • Barnebar
  • Bielefelder Kennhuhn – Created from Welsummer crossed with Cuckoo Malines.
  • Brockbar – Created from a buff Plymouth Rock crossed with a Barred Plymouth Rock.
  • Brussbar – Created from a brown Leghorn crossed with a Light Sussex.
  • Buffbar
  • Cambar – Created from a Campine crossed with a Barred Plymouth Rock.
  • Cobar
  • Cream Legbar Created from a Brown Leghorn, Araucana, and Barred Plymouth Rock.
  • Dorbar – Created from a Dorking crossed with a Barred Plymouth Rock.
  • Gold Legbar 
  • Hambar
  • Niederrheiner
  • Norske Jaerhon
  • Oklabar
  • Polbar
  • RhodebarCreated from a Rhode Island Red and Barred Plymouth Rock
  • Gold Welbar – Created from a Welsummer crossed with a barred Plymoth Rock
  • Whealbar
  • Wybar – Created from a Wyandotte crossed with a Barred Plymouth Rock and a Brusssbar

Autosexing chicken breeds pages

Cream Legbar Chicken

Legbar Chickens

No. of Eggs  4.5/5 Easy to Keep?  3.5/5 Uses: Autosexing, Utility Blue Egg Layer.Origin: Cambridge, UK. Eggs: White / Cream or Blue / Green for the Cream

Rhodebar Chickens

No. of Eggs  2.8/5 Easy to Keep?  3.5/5 Uses: Utility – eggs and meat. Origin: UK.  Eggs: 180 to 200. Weight: Cock: 3.85 Kg. Hen: 2.9 Kg. Bantam: Cock: 1020

Autosexing example: The Cream Legbar

Cream Legbars are autosexing chickens. They are a pure breed but were created from a cross between the Brown Leghorn, Araucana, and Barred Plymouth Rock. In this example, we can see the colour of their down can determine their sex shortly after hatching.

Autosexing Cream Legbar Chicks
Autosexing day-old Cream Legbar chicks (male on the right).

The barring pattern is sex-linked, i.e. the males have two chromosomes for barring and the females only one.

Day-old chicks have a light patch on the top of the head. When the barring is combined with brown colouring, the light spot on the head of the females is small, and there is a clearly defined dark brown stripe down the back.

The stripe down the back of male chicks is much fainter, and there is a light yellow patch that covers most of their head. The down of the male chick is also much paler and silver.

Why are there no Autosexing ducks?

Why are there no autosexing duck breeds? Well, ducks can be vent sexed when young and there are obvious differences in domestic ducks between the duck and drake when they are adults so there has never really been a need for autosexing duck breeds.

Autosexing goose breeds

While geese can also be vent sexed, it isn’t quite as easy as ducks. There were two breeds of autosexing goose created:

West of England, and Pilgrim.

Pilgrim Goslings
Autosexing Pilgrim Goslings

Pilgrim Geese

Uses: Utility – meat, relatively fast growing. Autosexing. Origin: UK. Eggs: 20 to 40 white eggs per year. Weight: Gander: 6.3 – 8.2 Kg. Goose: 

West of England Geese

Uses: Utility – meat and eggs. Useful autosexing characteristic. Eggs: 20 to 50 white eggs per year. Origin: UK. Weight: Gander: 7.3 – 9.1 Kg.

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Rhodebar Chickens

No. of Eggs  2.8/5 Easy to Keep?  3.5/5 Uses: Utility – eggs and meat. Origin: UK.  Eggs: 180 to 200. Weight:

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Cream Legbar Chicken
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Legbar Chickens

No. of Eggs  4.5/5 Easy to Keep?  3.5/5 Uses: Autosexing, Utility Blue Egg Layer.Origin: Cambridge, UK. Eggs: White / Cream or Blue

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A popular question from people incubating and hatching eggs is how to sex chicks? – how can you tell if they are male or female? Sexing chicks while young isn’t easy, but as they start to grow, there are some tell-tale signs to look out for.

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