Hen feathering in cocks

Hen feathering in cocks is the occurrence of a genetically conditioned character in domestic fowl (Gallus gallus domesticus). Males with this condition develop a female-type plumage, although otherwise look and respond as virile males.

Hen-feathering in cocks is one of the typical characteristics of the Belgian breed Campine and also is typical in Sebright Bantam, a breed established circa 1810, in accordance with the intentions of its creator, Sir John Saunders Sebright. It is also a condition found with lower frequencies in other breeds such as Hamburgs, Wyandottes and Games.

Sexual dimorphism in plumage is very common in birds, particularly within Phasianidae where males are bigger and have brighter and more colorful plumage than females among other morphological differences.

Males of most chicken breeds distinguish from their females in having longer, sharp and more scalloped feathers in neck, hackle, saddle and wing bows. But in some breeds, like the fancy breeds Sebright and Campine and some game breeds like Pettai Madhirione can see males that have a plumage completely similar in all aspects to that of females. This unusual type of feathering called so much the interest of biologists that was studied from different points of view, and as a consequence, the inheritance of this condition has been well understood, while the biochemical basis determining this condition is still under study.

It had been early established that hen-feathering is a trait controlled by a simple autosomic dominant gene, whose expression is limited to the male sex

The genetic symbol proposed by F. B. Hutt in 1958 to designate this autosomic dominant gene was Hf (after "hen feathering") which was accepted by other geneticists. Both homozygous Hf/Hf and heterozygous Hf/hf males are of the hen-feathering type, while hf/hf are of the normal feathering type. Meanwhile female carriers of Hf gene can not be identified unless they are submitted to progeny tests.

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